infamous 5MT low idle stall

[mbtoloczko]

After the 5MT swap, my car was stalling occasionally when I would push in the clutch when bringing the car to a stop or pulling into a driveway, etc. I was hoping the ECU would sort itself out and the stalls would cease, but it didn't happen. Then, I was hoping that when I rewired the ECU input to make the car think it was in neutral, that would fix the problem. It hasn't though. I've been looking through the threads here, and it appears that everyone with a 5MT has the same stalling problem. Anyone found a fix?

[svxsubaru1]

I never had had the probelm, and iam using the NSS to let it run right now. My car does idle at around 500 rpms tho, right on very bottom bar on the tach.

[SVXer95]

I still have the 4eat, but I have a similar issue that may or may not be related. Possibly if we figure out one it will be the answer for the other.

When I put my car in park with it idling, and move the selector toward reverse without using the brake or pushing the shift button, the car goes into a high idle. After letting go, it tries to stall. I understand why it would idle high while doing that, but I don't get why it tries to stall. Sometimes it stalls (very rarely) and most of the time the rpms just dip way down without stalling.

Perhaps the two are related and it is not a MT thing. Possibly a computer related issue like you thought.

[deruvian]

Perhaps you should consider raising the idle RPMs. Let's be realistic, eh? The SVX engine is still smooth and quiet at, say, 900 RPM. That factory default of 610 is a little conservative just for the purpose of keeping things quiet in the car.

You've got a Stebro anyways, Mychailo. :D

I believe I once remember NikFu mentioning that he has raised his idle RPMs to about 900 - 1000. I don't remember how though.

[mbtoloczko]

It seems that there is no idle adjustment. The idea of adjusting the idle has been tossed around quite a bit in the forums, but the consensus is that the ECU sets the idle, and there's no way to adjust it. Its too bad because it sits right at 600 rpm now, and if I could get it up to 800 rpm, that would solve the problem.

[BLKSVX92]

mine also does this. It has happened while turning(scary) and other times. However, it is not consistent, it doesn't happen all the time, it seems to happen only when it wants to.

[Chiketkd]

Mychailo, have you ever posed the question of idle adjustment to red95svx? He might know (or could ask one of the mechanics at his dealership) how to adjust the idle on the SVX, and if not he could send a request to Subaru of America...

Just a thought.

-Chike

P.S. On most manual cars (like my old '90 300ZX TT and '95 Camaro) there is an idler adjustment screw near to the throttle body that can be adjusted with a screw driver. Automatics are probably different though (as all SVX's started out this way)...
Originally posted by mbtoloczko
It seems that there is no idle adjustment. The idea of adjusting the idle has been tossed around quite a bit in the forums, but the consensus is that the ECU sets the idle, and there's no way to adjust it. Its too bad because it sits right at 600 rpm now, and if I could get it up to 800 rpm, that would solve the problem.

[Green1995SVX]

I havent experianced this condition.

[mbtoloczko]

Originally posted by Green1995SVX
I havent experianced this condition.

Cool. That means I should be able to stop it from happening on my car. I guess I'll have to clean the throttle body again and clean the IAC.

[Phast SVX]

i havnt experienced any stalling either? sorry:confused:

[BLKSVX92]

I'm curious if it has to do with the trannies that we are swapping

I have an 02 wrx tranny and it happens to me

[SVXer95]

Or more importantly the clutch type of the trannies that are being used? (push/pull)

[svxpert]

I havent experianced this condition, either.

[mbtoloczko]

Originally posted by SVXer95
Or more importantly the clutch type of the trannies that are being used? (push/pull)

I don't think its due to any sort of clutch drag. Sometimes, the revs decrease so quickly, the rpms pass quickly below 600 rpm, and the ecu can't react quickly enough to bring the revs back up, and the motor just stops spinning. I think it may be partially due to the 13 lb flywheel.

[Chiketkd]

That's a good point. Lightened flywheels will do that...

-Chike
Originally posted by mbtoloczko
I think it may be partially due to the 13 lb flywheel.

[want-a-fast-svx]

Originally posted by BLKSVX92
I'm curious if it has to do with the trannies that we are swapping

I have an 02 wrx tranny and it happens to me

me too and i've even tried to adjust the idle at the engine with the throttle cable and still no avail...I'm hoping its a ground or something cause it's reallly a problem not knowing when im slowing down for a light if the car is going to stall or not...I feel like im driving my old jeep again, i have to keep feathering the throttle in fear of it stalling...

[want-a-fast-svx]

Originally posted by mbtoloczko


I don't think its due to any sort of clutch drag. Sometimes, the revs decrease so quickly, the rpms pass quickly below 600 rpm, and the ecu can't react quickly enough to bring the revs back up, and the motor just stops spinning. I think it may be partially due to the 13 lb flywheel.

stock flywheel hear and you just described precisely what happens on mine..A sudden drop that the computer doesn't have time to react to..

[BLKSVX92]

i also have the stock flywheel well at least it seems the problem is limited to those with the wrx tranny :( just bad news for us

[mbtoloczko]

There's really not much difference internally between the WRX tranny and the other Subaru AWD 5MT trannys. The clutch actuation mechanism is different, but I can't see that its causing a problem. I always push the clutch in all the way, and I know its not dragging.

[GreenMarine]

Originally posted by mbtoloczko
After the 5MT swap, my car was stalling occasionally when I would push in the clutch when bringing the car to a stop or pulling into a driveway, etc. I was hoping the ECU would sort itself out and the stalls would cease, but it didn't happen. Then, I was hoping that when I rewired the ECU input to make the car think it was in neutral, that would fix the problem. It hasn't though. I've been looking through the threads here, and it appears that everyone with a 5MT has the same stalling problem. Anyone found a fix?

I've had this problem before... Though I haven't noticed it lately.. :rolleyes: But it is there in my car... Ya think it is just the 1995's ??? :):)

[mbtoloczko]

Originally posted by GreenMarineSVX


I've had this problem before... Though I haven't noticed it lately.. :rolleyes: But it is there in my car... Ya think it is just the 1995's ??? :):)

You got me thinking for a minute, but then I rememberd that Mike's car is a '95, and his does not have the idle stall.

[BLKSVX92]

Originally posted by mbtoloczko


You got me thinking for a minute, but then I rememberd that Mike's car is a '95, and his does not have the idle stall.

Don't forget I havea 92 and I am plagued with the problem

[huck369]

I've never had this problem in my 92....always idles fine

[mbtoloczko]

For the last couple days now (basically since I wrote this post), my car has been not been stalling!! Maybe if I start complaining about my worn tires they'll get some new tread on them. :-)

[mohrds]

I think it is a tune up issue. {Puts on Flame suit}

I had that issue on my 92 (auto tranny) all the time until I swapped out the engine. I would put it in neutral and it would occasionally die.

After I swapped out the engine, it never did that again.

Looking at my old engine, some of the vacuum lines at the rear were showing their age and the throttle body and intake runner were filthy even though I cleaned it on a somewhat regular basis.

Just a shot in the dark, but with all the messing around with the physical install, could some of the vacuum lines have gotten flexed enough where the age fatigue produced a tiny crack? That would explain why it mostly happens to cars after a 5 speed swap.

Doug

[mbtoloczko]

Originally posted by mohrds
I think it is a tune up issue. {Puts on Flame suit}


Stop making sense! :-))

[mohrds]

Originally posted by mbtoloczko


Stop making sense! :-))

I can't help myself. I am going to a Sense Makers Support Group to try and stop. :D

Doug

[want-a-fast-svx]

Originally posted by mohrds
IJust a shot in the dark, but with all the messing around with the physical install, could some of the vacuum lines have gotten flexed enough where the age fatigue produced a tiny crack? That would explain why it mostly happens to cars after a 5 speed swap.

Doug

yes...this is a very likely possibility, i will have to take a hard and long look at the vaccum lines, however this engine only has 50,xxx on it and i just swapped it not to long ago, however a line or two could be loose or have a hole in it. I do remember though when i replaced the engine i replaced every inch of rubber line i saw for this very reason. Hopefully its just a loose vaccum hose...

[THAWA]

for those of you comparing flywheel weight, you also need to remember that even though the flywheel you put on may be stock it's still not nearly as heavy (slower to slow down) as the stock torque converter. I think that's the main problem with it.

[Earthworm]

Mine also stalls occasionally with the 5 spd (2002 WRX). I compensate for this by not depressing the clutch until RPM's are already at 600 or so. (Unless I'm downshifting coming out of a corner)

[want-a-fast-svx]

anyone have any luck with the stalling issue at hand?

[Beav]

Sounds as though the IAC isn't programmed to recover the idle fast enough for a manual tranny. You might adapt a dashpot from a '70s carbureted car to the throttle, whether at the linkage or the pedal, in order to slow the throttle closure a tad. Typically a dashpot will add a half-second or so to the closure time. Many different types/brackets/etc. available. Browse an old junkyard or check out NAPA, Autozone online, etc. Try this for an idea:

http://www.napaonline.com/cgi-bin/ncommerce3/ExecMacro/NAPAonline/search_results_product_detail.d2w/report?prrfnbr=15538101&prmenbr=5806&usrcommgrpid=75294599

It's just a diaphragm that depletes through a small hole, pretty basic.

[mbtoloczko]

Sounds as though the IAC isn't programmed to recover the idle fast enough for a manual tranny. You might adapt a dashpot from a '70s carbureted car to the throttle, whether at the linkage or the pedal, in order to slow the throttle closure a tad. Typically a dashpot will add a half-second or so to the closure time. Many different types/brackets/etc. available. Browse an old junkyard or check out NAPA, Autozone online, etc. Try this for an idea:

http://www.napaonline.com/cgi-bin/ncommerce3/ExecMacro/NAPAonline/search_results_product_detail.d2w/report?prrfnbr=15538101&prmenbr=5806&usrcommgrpid=75294599

It's just a diaphragm that depletes through a small hole, pretty basic.

That's the best idea I've heard yet. Thank you.

[svxsubaru1]

I never had had the probelm, and iam using the NSS to let it run right now. My car does idle at around 500 rpms tho, right on very bottom bar on the tach.


Now my car does have the stalling issue, it went for about 1/2 a year with out it. hopefully its tune up/Vacume hose thing.

[Speedklix]

I think it is a tune up issue. {Puts on Flame suit}

I had that issue on my 92 (auto tranny) all the time until I swapped out the engine. I would put it in neutral and it would occasionally die.

After I swapped out the engine, it never did that again.

Looking at my old engine, some of the vacuum lines at the rear were showing their age and the throttle body and intake runner were filthy even though I cleaned it on a somewhat regular basis.

Just a shot in the dark, but with all the messing around with the physical install, could some of the vacuum lines have gotten flexed enough where the age fatigue produced a tiny crack? That would explain why it mostly happens to cars after a 5 speed swap.

Doug

Yahtzee!!!
My Auto 92 did this exactly. It only did it after I had not driven it for several weeks, and only in the cold. I know it has a vacumm leak somewhere but never hunted it down, I always blamed it on this. My leak has to be to the rear somewhere, which would be the same place a 5mt swap would cause a problem.

[blacknite]

I Just Started Having The Same Issue, A Few Days Back I Opend The Hood And Look Aroud The Altertanor And Ps. And Right Underneath The Intake A Little Hose From The, I Guess Iris System Was Just Laying On Top Of The Block So I Put It Where It Belongs And After That I Started Having The Stall Problem....

[mbtoloczko]

Yahtzee!!!
My Auto 92 did this exactly. It only did it after I had not driven it for several weeks, and only in the cold. I know it has a vacumm leak somewhere but never hunted it down, I always blamed it on this. My leak has to be to the rear somewhere, which would be the same place a 5mt swap would cause a problem.

For a while, I was convinced that it was an air leak issue, but more recently, I think its not. The only time the engine stalls is when reving down when coming up to a stop sign/signal. Nine times out of ten, with the enging at say 2500 rpm, when I let off the gas and push in the clutch coming up to a stop, the rpms drop quickly but the IAC kicks in, and the rpms settle momentarily at about 1200 rpm before slowly settling down to about 650 rpm. Once in a while though, when I let off the gas and push in the clutch, the IAC never kicks in, and the rpms just go straight to zero.

[Earthworm]

Then why did it seem to only be a problem with people using WRX trannies?

[huck369]

Could it be a problem only with people running lightened flywheels, as they don't carry enough rotating mass to keep the EG33 from stalling?

[deruvian]

For a while, I was convinced that it was an air leak issue, but more recently, I think its not. The only time the engine stalls is when reving down when coming up to a stop sign/signal. Nine times out of ten, with the enging at say 2500 rpm, when I let off the gas and push in the clutch coming up to a stop, the rpms drop quickly but the IAC kicks in, and the rpms settle momentarily at about 1200 rpm before slowly settling down to about 650 rpm. Once in a while though, when I let off the gas and push in the clutch, the IAC never kicks in, and the rpms just go straight to zero.

Mychailo, last night I was thinking about our previous conversations about this. I wonder if there is a way to trick the ECU into thinking it is in "cold start" mode all the time? This usually causes the engine to idle at about 1000 - 1200 RPM, and while this may *bother* some people, I certainly think it would be an advancement if the car never stalled.

[mbtoloczko]

Mychailo, last night I was thinking about our previous conversations about this. I wonder if there is a way to trick the ECU into thinking it is in "cold start" mode all the time? This usually causes the engine to idle at about 1000 - 1200 RPM, and while this may *bother* some people, I certainly think it would be an advancement if the car never stalled.

The engine runs only in open-loop when the ecu is in cold-start mode. Open-loop would likely make gas mileage even worse. It might also be that the ecu richens the a/f ratio in cold start mode. Might be interesting to try, but I think I'm going to go with Beav's suggestion of adding a dashpot to slow the return of the throttle to idle position.

[blacknite]

I'm Using The 1996 The Turbo Legacy Flywheel And Clutch, The Diameter Is Bigger Than Wrx. And Have The Same Problem....

[robricc]

Just to chime in, I have a 92 with 2002 WRX 5MT and have this exact problem lately. It didn't happen for a couple months, but once it got colder it started.

[rmjjensen]

reviving an old thread - the last post seems to be from March of 2005.

I'm starting my conversion and who knows if I'll wind up with this problem. I'll be using an '04 WRX tranny with a stock WRX flywheel.

Everyone that has done this swap has tricked the ECU into thinking it is in N or P correct? Why not leave it to think the transmission is in the D position? I know that there is high idle involved in that trick but I'd think it would be easier to lower the idle output from the ECU rather than raise it.

[AvPPoW]

I dont have this problem, but it's not cold here yet. We'll see

[TomsSVX]

I only began to have this problem when I swapped my 94 motor out for a 92 with less mileage. I did check all of the vaccum lines before the install. I also used the TB from my 94 motor, so I think it is something to do with...... I have no idea :eek: :cool:

Tom

[huck369]

reviving an old thread - the last post seems to be from March of 2005.

I'm starting my conversion and who knows if I'll wind up with this problem. I'll be using an '04 WRX tranny with a stock WRX flywheel.

Everyone that has done this swap has tricked the ECU into thinking it is in N or P correct? Why not leave it to think the transmission is in the D position? I know that there is high idle involved in that trick but I'd think it would be easier to lower the idle output from the ECU rather than raise it.


The Starter won't engage if the ECU thinks the car is in drive, hence the need to trick it into thinking its in Nuetral or Park, but if you wire in the Clutch position switch, it only thinks it's in nuetral when you have the clutch depressed...., it thinks it's in drive when not on the clutch...

[shotgunslade]

Thought I would resurrect this old thread because it seems to be a problem that hasn't yet been fully resolved. Now I'm in it big as the proud new owner of a 5MT, reportedly with the stall chartacteristic. (Don't yet have personal experience with it yet, as I haven't yet picked up my car from Tom). In Tom's latest 5MT installed thread, there was a lot of discussion of the issue, before the conversation took a different turn. I got interested by the dashpot idea, and did some web-searching. Seems like stalling with carburetted engines was a pretty common problem, and dashpots were a common solution. Since I don't have my car yet, can't even look at the throttle lever and cable hook-up to see if a dashpot could be fitted in to slow the closure of the throttle when the cable is released. There seem to be dashpots available, so I guess its just a question of whether or not one can be attached in the right position.

[TomsSVX]

anything can be done Dan, even if I have to fab up a couple brackets to make it work.

Tom

[shotgunslade]

So this is what a dashpot looks like in concept
http://www.sweethaven02.com/Automotive01/fig0441.gif

And here's one for sale at Summit Racing.

http://static.summitracing.com/global/images/prod/large/hly-11-4_w.jpg

[TomsSVX]

I would have to have it in my hands and under the hood to say if I could definately do it or not

Tom

[mbtoloczko]

I've scoped it out. There's enough room to do it, and the layout is ok for it. Its just a matter of fabricating brackets.

[shotgunslade]

Summit Racing and maybe others have brackets for mounting the dashpot. It might be easier to mod them. Take a look at their catalogue.

[Jade Dragon]

To raise the idle, its easy. I did this to my 93 legacy. unscrew your TPS and adjust it up/down until you find the idle you want. the ecu thinks its getting the correct data, so it wont adjust it down

[shotgunslade]

The dashpot doesn't really raise the idle speed. It basically acts as a cushion to give the throttle actuator lever a soft landing when it is abruptly released by lifting off the accelerator. The throttle closes normally and the idle is at normal speed after a brief delay. This delay avoids stalling the engine.

[longassname]

The dashpot sounds like a good idea. Are any of you working on that? Just for my own information/curiosity does anybody with a manual transmission from a non turbo car have the stall problem? It seems to me if everyone who has the pull type throw out bearing has the stall problem and nobody who has the push type throw out bearing does that that is good information to know. When our understanding and the facts don't mesh it's our understanding that needs to change.

[TomsSVX]

My Sti 6 speed doesn't stall. And my old 4.115mt from an N/A imprezza did. it is more reliant on the engine than anything else. When I blew my 94's motor, I swapped in a 92 engine. Then it started to stall. Take that for what you will

Tom

[longassname]

got ya. well you are around a lot of manual conversions do you think the stall problem is more common with the pull type clutch or is it a completely irrelevant coincidence that so many of the people with the stall problem have the wrx tranny?

So anybody tried the dash pot yet? It seems to me if it's air then the dashpot will fix it. If it's fuel then I'll fix it. I'm going to change the minimum pulsewidth in stage 2v6.

[SVXRide]

got ya. well you are around a lot of manual conversions do you think the stall problem is more common with the pull type clutch or is it a completely irrelevant coincidence that so many of the people with the stall problem have the wrx tranny?

So anybody tried the dash pot yet? It seems to me if it's air then the dashpot will fix it. If it's fuel then I'll fix it. I'm going to change the minimum pulsewidth in stage 2v6.

Michael,
Any feel for when you'll have the 2v6 chip available?
-Bill (currently planning on installing his 2v5 chip today...)

[TomsSVX]

I feel the ECU is to blame. It is not setup for a Manual trans so when the engine is on decel, there is next to no rotational mass attached so it drops too fast for the IAC to compensate for. If you could fix it to speed up the IAC's reaction I feel the problem would be solved

Tom

[longassname]

Not really Bill,

I wouldn't wait for it. A lot of it will be done as part of the stage 3 tuning which will be completed within two weeks. After that I will be asking everyone what they want to make sure I incorporate as many people's wishes and desires into it. So depending on what people want we will see. I also want to make sure we solve the 5mt stall problem with it if it turns out to be something better handled by the ECU than a dashpot. That's why I'm asking about the dashpot now.

[SVXRide]

Not really Bill,

I wouldn't wait for it. A lot of it will be done as part of the stage 3 tuning which will be completed within two weeks. After that I will be asking everyone what they want to make sure I incorporate as many people's wishes and desires into it. So depending on what people want we will see. I also want to make sure we solve the 5mt stall problem with it if it turns out to be something better handled by the ECU than a dashpot. That's why I'm asking about the dashpot now.

Michael,
Thanks for the quick response! I'm inclined to agree with Tom on the stalling issue - the engine control system is set up to work with an automatic trans and its inherent hydraulic "lag". Once you swap in the manual trans you lose that aspect of the overall control loop. I like your idea of reducing the pulse width as a way of addressing this.
It is curious that Tom's 6 spd doesn't stall. I don't know exactly how the 5spd varies from the 6 spd, but I'm guessing the 5spd transmissions don't have as much rotational mass...
-Bill (walking out to the garage to install a 2v5 chip....)

[longassname]

Tom, if it is air then the dashpot is the solution. When you talk about changing the way the IAC operates you are talking about major code changes. The direct hardware solution of the dashpot is much simpler and effective. The changes I can make to IAC operation through data are limited.

Now if it's a fuel problem that's a different story. I can address that directly by changing the minium pulsewidth to prevent engine stall.


I feel the ECU is to blame. It is not setup for a Manual trans so when the engine is on decel, there is next to no rotational mass attached so it drops too fast for the IAC to compensate for. If you could fix it to speed up the IAC's reaction I feel the problem would be solved

Tom

[TomsSVX]

I think the air is to blame as well. Since I know so little of the coding in the ECU I had no idea it would be a huge task. Like I have said, it is due to the engine not the transmission so the thoughts of my 6 speed not stalling for any reason outside of my engine running properly s false. The trans makes no difference, I have a feeling that engine that may be using oil or have busted vaccum lines may be more prone to stalling. Also lightweight flywheels and pulley will not help. The dash pot seems like our only way out, I will go ahead and order one and see if I can get around to installing it

Tom

[longassname]

Bill,

I would most likely not reduce the minimum pulse width. If it's rich during the stall it's because there isn't enough air not because there is too much fuel. In this case the dashpot is needed. There is a minimum amount of air and fuel needed to keep the engine running. You can't just cut fuel to match not enough air and expect it to run. If it is lean during stall I will increase the minum pulse width and the problem will be fixed. This could also easily be the problem. In other cars it often is. If my car had a manual transmission I would answer this question on day 1 but it doesn't so one of those who does will have to try the dashpot.

Michael,
Thanks for the quick response! I'm inclined to agree with Tom on the stalling issue - the engine control system is set up to work with an automatic trans and its inherent hydraulic "lag". Once you swap in the manual trans you lose that aspect of the overall control loop. I like your idea of reducing the pulse width as a way of addressing this.
It is curious that Tom's 6 spd doesn't stall. I don't know exactly how the 5spd varies from the 6 spd, but I'm guessing the 5spd transmissions don't have as much rotational mass...
-Bill (walking out to the garage to install a 2v5 chip....)

[TomsSVX]

thinking about it more, I am not sure I will be a good test subject as my car doesn't stall. It does accasionally take a quick dive but the ECU recovers quickly

Tom

[Earthworm]

Mine (2002WRX) has stalled previously (after a thorough TB cleaning and the Stage I chip it stopped).

My dad's (not exactly sure which tranny but probably Impreza 4.11 cable clutch) never stalls.

My bet is still on a slow reacting IAC.

[longassname]

Ya it would be better if it was done on a car that has a worse problem. Perhaps someone would like to hire you to install a dashpot on their mt svx.

thinking about it more, I am not sure I will be a good test subject as my car doesn't stall. It does accasionally take a quick dive but the ECU recovers quickly

Tom

[TomsSVX]

Well Shotgunslade just drove his car away a few hours ago. He said on his test drive it did not stall. It is only on occaision unless you are running a fuel pressure too high. My stage2v4 did it all the time because it was running too rich. This also helped me come to the conclusion of not having enough air. I just cranked out the idle screw a little until I got the stage2v5 as a temp fix

Tom

[mbtoloczko]

It did occur to me yesterday that there is one instance where the dashpot may not prevent the stall. I have found that sometimes during a long decel with the tranny in gear and coming up to a stop sign (say taking a freeway offramp), as I come up to the stop sign and put the car in neutral, the engine will stall. A dashpot will have allowed the throttle body to have closed long before I reach the stop sign, so it seems to me that the dashpot may not help here.

With my car, I don't think the stall has to do with the tranny having a pull clutch. There is no change in idle speed with the clutch engaged or disengaged. Turning the steering wheel when coming up to a stop will exacerbate the stall though. The extra load placed on the engine by the PS makes it more difficult for the engine to recover from a very low idle. I've cleaned the throttle body and IAC very thoroughly and all the vacuum lines are brand new, so I think the lightweight flywheels definitely contribute to the stalling.

[TomsSVX]

Yes but the Dash pot will allow the throttle to ease shut so they engine should be more stable at idle. I think it would even help the case of an extended stop like you mention.

Tom

[Earthworm]

Are they adjustable? It would have to hold the throttle for at least 10 seconds.

[shotgunslade]

Having driven the car some now, trip home from Beach Haven and around Princeton, I have experienced the stall a couple of times. A couple of observations, though. I think the clutch pedal has to be pushed completely to the floor in order to disengage fully the clutch, because there is difficulty downshifting into first gear, unless I stand on the clutch pedal, so I think at least one of the stalls may have been related to coming to a stop in first with the clutch pedal only almost to the floor. Also, I think giving the accelerator a very slight blip just up to 1500-1800 rpm right after disengagement as you are coming to a stop, allows it to settle more slowly into a stable idle. I think the dashpot might completely eliminate the problem, but I think some learned behavior will probably eliminate most occurrences.

Love the car. Will start a thread on my first impressions. Thanks very much Tom.

[SVXRide]

Bill,

I would most likely not reduce the minimum pulse width. If it's rich during the stall it's because there isn't enough air not because there is too much fuel. In this case the dashpot is needed. There is a minimum amount of air and fuel needed to keep the engine running. You can't just cut fuel to match not enough air and expect it to run. If it is lean during stall I will increase the minum pulse width and the problem will be fixed. This could also easily be the problem. In other cars it often is. If my car had a manual transmission I would answer this question on day 1 but it doesn't so one of those who does will have to try the dashpot.

Michael,
Agreed.
-Bill (2v5 install shifted to Sunday....Saturday spent on "BillStock" stock muffler mod v2...yes, stainless steel wool will cut your fingers if you're not careful:eek: )

[mohrds]

I think the clutch pedal has to be pushed completely to the floor in order to disengage fully the clutch, because there is difficulty downshifting into first gear, unless I stand on the clutch pedal, so I think at least one of the stalls may have been related to coming to a stop in first with the clutch pedal only almost to the floor.

Does your car use the donor car's pedal assembly or did you modify the SVX assembly to accept the clutch and brake pedals? One of the things I noticed when working on my swap is that the legacy pedal setup sits a good 3/4 - 1 inch closer to the firewall than the SVX brake pedal does. For that reason I mounted the individual pedals to the SVX assembly to keep the pedals at the same location as the SVX.

However, the swap isn't finished :( so I can't say if this affects the idle issue or not. I can't even say if my car will suffer from the issue.

Doug

[TomsSVX]

Dan, the clutch release is adjustable. I set it there and since there was full engagement did not move it. If you would like it moved out I can show you how to do it

Tom

[shotgunslade]

Tom:

Thanks. I'm just getting used to it. It's been 8 years and 2 SVX's (this one is now so different it has to count as a 3rd) since I drove stick as a daily driver. Sheila and I were talking today about my previous cars, and all before the SVX's had been manual. Two VW Beetles, a Chevy El Camino, a BMW 2002tii, a Fiat Spider, an Alfa Romeo Berlina, a Honda Prelude, and a Porsche 911, but 8 years is pretty long. Upshifting is not a problem, nor downshifting into anything but first. They go smoothly without consciously making sure the clutch pedal is on the floor. Maybe I'll make a list of adjustments and some further minor mods, and take a trip down to Beach Haven in a little while and buy some of your time. If you guys work out a dashpot thing, I'll definitely be buying one of those.

Mohrds:

I bought a complete Sti pedal assembly on eBay, and Tom rebuilt it and used it as a complete replacement for the SVX pedal assembly.

[TomsSVX]

Dan, sounds like a good idea. I never downshifted into 1st in any of my vehicles. I wait until I am stopped to put it into 1st. The synchos are always tight and I feel like I am going to break something when I do it. Thats not the clutch pedal but more the transmission holding it back.

Tom

[oab_au]

It did occur to me yesterday that there is one instance where the dashpot may not prevent the stall. I have found that sometimes during a long decel with the tranny in gear and coming up to a stop sign (say taking a freeway offramp), as I come up to the stop sign and put the car in neutral, the engine will stall. A dashpot will have allowed the throttle body to have closed long before I reach the stop sign, so it seems to me that the dashpot may not help here.

With my car, I don't think the stall has to do with the tranny having a pull clutch. There is no change in idle speed with the clutch engaged or disengaged. Turning the steering wheel when coming up to a stop will exacerbate the stall though. The extra load placed on the engine by the PS makes it more difficult for the engine to recover from a very low idle. I've cleaned the throttle body and IAC very thoroughly and all the vacuum lines are brand new, so I think the lightweight flywheels definitely contribute to the stalling.

There does seem to be a couple of things going on. The sudden closing of the throttle, can be over come with the dash pot.

The stalling when running to the stop, with a closed throttle, is more a ECU problem. First the ECU has been told that the trans is in N, so it has been trying to control the idle speed, that it should be able to in this condition. But the engine is not free to control. The engine speed is being controlled by the drive train.

When running into a corner with a closed throttle, the ECU is trying to slow the idle down. So it winds the Idle Control unit down, but the engine does not respond, so it winds it down further. Then you get to the stop, push the clutch in, all of a sudden now, the engine can responded but, because the Idle Control unit has wound the control right down, the engine stalls.

To fix it you may have to try different positions of the ECU N, P, D, shift inputs to cure the problem.

Harvey.;)

[mbtoloczko]

...

When running into a corner with a closed throttle, the ECU is trying to slow the idle down. So it winds the Idle Control unit down, but the engine does not respond, so it winds it down further. Then you get to the stop, push the clutch in, all of a sudden now, the engine can responded but, because the Idle Control unit has wound the control right down, the engine stalls.

To fix it you may have to try different positions of the ECU N, P, D, shift inputs to cure the problem.

Harvey.;)

This is pretty much what I feel is happening with the light flywheel exacerbating the problem. I've got the ECU pinouts jumpered to make the ECU think the non-existent 4eat is in neutral. When I had it set to think the 4eat was in drive, the problem was worse. I'm thinking that a dashpot is an inexpensive solution that would help in some instances, but if there was a way to modify the IAC algorithm, that would be the ideal solution.

[oab_au]

This is pretty much what I feel is happening with the light flywheel exacerbating the problem. I've got the ECU pinouts jumpered to make the ECU think the non-existent 4eat is in neutral. When I had it set to think the 4eat was in drive, the problem was worse. I'm thinking that a dashpot is an inexpensive solution that would help in some instances, but if there was a way to modify the IAC algorithm, that would be the ideal solution.

I was think more of the P being used, with the clutch switching it over to N when it is pushed. So that the ECU won't be trying to control the idle speed, on a closed throttle overrun, till the clutch is pushed.

Harvey.;)

[oab_au]

What I meant was that the N, P, inputs to the ECU be left open, so the ECU knows that the trans is in gear. The N be switched on, when the clutch is pushed or the box is in Neutral.
This would stop the Ecu from trying to stabilize the idle speed when it is coming to a stop.

Harvey.;)

[huck369]

What I meant was that the D, P, inputs to the ECU be left open, so the ECU knows that the trans is in gear. The N be switched on, when the clutch is pushed or the box is in Neutral.
This would stop the Ecu from trying to stabilize the idle speed when it is coming to a stop.

Harvey.;)

But that would keep the cruise control from working....

[TomsSVX]

you don't want the cruise to when the car is in N anyway. This still will not cure the stalling problem though. The neutral switch in Shotgunslade's pedal assembly was not working properly so I had to hardwire it in Neutral all the time so he could start it. It still stalls.

Tom

[Earthworm]

Do you have any problems shifting into 2nd gear from a stop?
If so either the return spring in the clutch master is sticking or you can adjust the rod on the clutch pedal. I've had both issues.

[TomsSVX]

the rod needs to be adjusted but it does allow for full release


Tom

[shotgunslade]

Observed this tonite on my drive home from the train station. Approaching a right hand turn, I'm in second gear, braking, about 2000-2200 rpm. Push down the clutch pedal, and turn. The rev's drop like a stone. Suprising how fast. Revs seem to hit zero, all warning lights light up, but then, without letting out the clutch, engine sort of restarts on its own, jumps up to 800 rpm, and settles at 600 or so. What caught my attention was the rate at which the revs dropped.

Contrast that with the next turn. Same thing, except, momentarily, I take my foot off the brake and lightly, very very briefly touch the accelerator, just as I push the clutch down. Rev's rise only as 100 rpm or so, but the rate of rev drop when my foot is completely off the pedal is much slower, and it hits 600 rpm and stays there briefly, until I let out the clutch and give it some gas as I straighten out .

Seems like the ECU is actively trying to kill the revs in the first instance, overshoots, and just catches it before it has a chance to die completely. Touching the accelerator in the second instance stopping that from happening. So, I bet, this wouldn't happen if the throttle butterfly didn't immediately close completely when you take your foot off the accelerator.

No problems shifting into second while I'm stopped, as long as the clutch pedal is depressed.

[oab_au]

This still will not cure the stalling problem though. The neutral switch in Shotgunslade's pedal assembly was not working properly so I had to hardwire it in Neutral all the time so he could start it. It still stalls.

Tom

Yes Tom that is what I have been saying.

Look at it, the way the Ecu does. The Ecu has been told that the trans is in N, so it waits for the 'closed throttle signal', when this arrives, it starts to control the idle speed. It does this by reading the RPM, if it is high it will tell the Idle Air Control to close a bit, it then reads the RPM to see if it is low enough, if not it will repeat the cycle till the RPM is OK.:)


Now look at what is happening. You have closed the throttle and are coming down in speed to stop. The Ecu now has to maintain the idle speed.

It should not have to do any thing, as the idle speed was right, last time the throttle was closed.:cool:

The Ecu reads the RPM, it's like 1700,:eek: the Ecu tells the IAC to close down, it keeps looking at the RPM, expecting it to fall. But because the engine is still being driven by the trans, it can't slow down.:confused:

Eventually you stop. The IAC has been closed right down, you push the clutch in, the engine is no longer driven, it will stall, unless the IAC can act fast enough, to pick the speed up.

This condition can be made worse if the IAC is sticky and can't respond fast enough. But the other condition of suddenly closing the throttle to stall, needs the dash pot.

I think Huck has the N on the clutch, so the Ecu won't be trying to set the idle speed, till he pushes the clutch in.:) It may work better if the N was switched by both, the clutch, and the N position on the gear box.

Harvey.;)

[oab_au]

Observed this tonite on my drive home from the train station. Approaching a right hand turn, I'm in second gear, braking, about 2000-2200 rpm. Push down the clutch pedal, and turn. The rev's drop like a stone. Suprising how fast. Revs seem to hit zero, all warning lights light up, but then, without letting out the clutch, engine sort of restarts on its own, jumps up to 800 rpm, and settles at 600 or so. What caught my attention was the rate at which the revs dropped.

Contrast that with the next turn. Same thing, except, momentarily, I take my foot off the brake and lightly, very very briefly touch the accelerator, just as I push the clutch down. Rev's rise only as 100 rpm or so, but the rate of rev drop when my foot is completely off the pedal is much slower, and it hits 600 rpm and stays there briefly, until I let out the clutch and give it some gas as I straighten out .

Seems like the ECU is actively trying to kill the revs in the first instance, overshoots, and just catches it before it has a chance to die completely. Touching the accelerator in the second instance stopping that from happening. So, I bet, this wouldn't happen if the throttle butterfly didn't immediately close completely when you take your foot off the accelerator.

No problems shifting into second while I'm stopped, as long as the clutch pedal is depressed.


You posted while I was writing.:) Amazing :D is this what I have been saying. The dash pot will do it on the fast slow down, but a long run down to a corner will still cause the IAC to close down. Bliping the throttle, turns the closed throttle signal off, so it does not have to set idle.
Harvey ;)

[rmjjensen]

Just something to kill all of your theories:

I do not have ANYTHING connected to my clutch pedal. Both switches are unplugged.

The ECU always thinks it's in Drive by me NOT grounding the P pin or the N pin coming from the Transmission harness. To start the car, the NSS on the transmission harness is jumped with a heavy gauge wire. Starting the car is not controlled by the ECU one bit, the NSS that was in the automatic transmission is what controls when the engine can start. Yes I don't have cruise control - and I don't care. Frankly the SVX cruise control is jerky the way it works - seems more like it doesn't smoothly control the throttle (maybe mine's broken but it's not necessary when I drive anyway).

With that said, my car is always in drive, regardless of what gear the 5MT is in or whether the clutch pedal is pushed in or out.

I have the 5MT idle stall once in a blue moon. It rarely happens but I can MAKE it happen. Generally when you are turning the wheel and suddenly push the clutch in it sometimes may stall. I believe this to be the power steering pump sucking the little juice that the IAC is feeding into the engine.

Want a fix? send +10V to the AC activation wire of the ECU. This will raise the idle to about 750rpms. At the same time, interrupt the output from the ECU that feeds the AC Compressor so it's not always on with a 9V relay. Take the wire coming from the HVAC that used to feed the ECU +10V when the AC Compressor is to kick on and feed it to the relay to activate the compressor when it's really needed and complete the connection you just interrupted. Only draw back is the dam cooling fans ...it can cause both to go on because it thinks the AC is going. I'd have to build a temp sensor circuit to control the fans externally - which wouldn't be hard at all - just lazy.

But it works - put your Defroster (or AC) on and unplug the trigger wire at the compressor temporarily - see if you can make the SVX stall ;)

[longassname]

I'm sure it's because people just don't remember what they did when they did their wiring when they are making their posts but I haven't seen any detailed description of how people have wired what for their manual transmission conversions. It might help.

I don't see any wiring that tells the ecu that the car is in the d range. For that matter I don't see any wiring that tells the ecu that the trans is in any range other than p or n. There are 3 wires which go to the ecu from the inhibitor switch on the 4eat. These are pins c10, b9, and b10. Pin b9 tells the ecu that the transmisison is in park. Pin b10 tells the ecu that the transmission is in nuetral.

Pin c10 tells the ecu that you are starting the car. c10 is a by colored wire in the ecu harness and is part of the starter interupt circuit of the 4eat. It should never see power except for when the igntion key is being turned to start the car, as such it should be on a seperate circuit from the nuetral wire. Is it possible some of you are sending power to this pin everytime you press the clutch?

Pin B9 tells the ecu that the transission is in park. I don't see any reason you would ever want to tell the ecu that the transmission you don't have is in park.

Pin b10 tells the ecu that the transmission is in neutral. I'll check on this tomorrow to be sure but I imagine connecting this to power whenever the clutch is pushed will prevent the fuel cut on decelleration.

[longassname]

There were some logs I wanted to get off the laptop so as long as I was in the car anyway I went ahead and checked. The neutral signal does dissable the fuel cut during decell. So the correct wiring is for the clutch to control 2 circuits which must be wired seperately. One circuit completes the ignition start signal to both the ecu and the starter. The 2nd circuit tells the ecu the car is in nuetral whenever the clutch is pushed.

[mbtoloczko]

For the first couple months after the 5MT went into my car, I drove my car with neither the park pin nor the neutral pin grounded, and the car would stall. For the last 1.5 years, I've been driving with the neutral pin grounded, and the car stalls this way too.

When you say that fuel cut is disabled during decel when the neutral pin is grounded, do you mean that fuel is metered according to airflow? I've always been curious about what is different between the neutral, park, and "D" settings on the ECU. I know one difference is that in the "D" setting, the ECU programmed to anticipate some small load on the engine during idle because of the torque converter. This is what causes the high idle that occasionally happens with 5MT cars that do not have the neutral pin grounded.

[longassname]

There is no d pin. There is an N pin and a P pin and there is a start pin.

The p pin tells the ecu the transmission is in park. There is no reason to use the p pin for a manual transmission.

The start pin tells the ecu you are starting the car. The start pin should receive it's signal when you are starting the car in order to engage the propper enrichments, coil dwell, ignition timing etc. The easiest way to wire this circuit is witch a switch on the clutch pedal which connects the wires from pin 11 and pin 12 from the inhibitor switch. This connects the ignition switch signal to both the ecu and the starter.

The N pin tells the ecu the transmission is in nuetral. The n pin needs to be recieve it's signal when the clutch is pushed in so that the ecu does not cut fuel during decel. I assumed it was a power signal but no it's a ground signal. You shouldn't just ground it all the time though. It should only be grounded when you push the clutch in. It would be nice if you could have it grounded while in nuetral too but that's not going to happen. You need it grounded when you push the clutch in though otherwise there will be times when the ecu will cut all fuel during decell not knowing the car is in the equivalent of nuetral..ie you have the clutch down. This will absolutely cause a stall.

You may still need a dashpot but you need to start with the ecu being wired propperly.

[longassname]

of course on that note you should keep in mind that nuetral is not the same as the clutch being pushed down. If you put it in nuetral and don't hold the clutch down you will still experience the fuel cut during some decells and stall. I'm afraid you will have to keep the clutch down untill you have settled at a stop to be sure you don't stall due to a decell fuel cut.

You have a lm1 don't you? You should be able to log this and see. There are times during decell, read from speed sensor 2, where the ecu cuts all fuel and you will get a reading at the max of the lm1 of an afr of 22 to 1. If the ecu is recieveing the nuetral signal it will not perform this fuel cut.

[shotgunslade]

So, if the ECU thinks the phantom 4EAT is in D, it will cut all fuel when the throttle is completely closed. If it thinks it is in neutral, it won't. So, if the scenario for, stalling is push in the clutch, change gears, but do not immediately let out the clutch, because you're busy turning, then you would get a stall if the ECU thought you were in D, because it would shut off all fuel when the throttle closed. If it thinks you are in neutral when you push down the clutch, it will see the elevated rpm's that you had when you pushed down the clutch, and will try mightily to get those down to idle, because the throttle is closed. If it tries too hard, by cutting fuel the car will stall. So, it seems whether the ECU thinks the car is in D or N, we will have a stallling situation. Practically, since this period of delayed clutch re-engagement is typically in the range of a couple of seconds, mechanically delaying full throttle closure would solve it, at least for me, with my driving habits.

[mbtoloczko]

There is no d pin. ....

I know that. If neither the park pin nor the neutral pin are grounded, then the ECU thinks the phantom 4eat is in drive. That's what I meant.

Under decel with the neutral pin grounded and with the tranny in gear, my LM-1 display shows 20.9% oxygen (which is a full lean condition). It doesn't start indicating the presence of any fuel until the rpms get pretty low. That's why I'm curious about your statement about there being no fuel cut during decel with the neutral pin grounded.

I don't see a point in wiring the neutral pin into a clutch pedal switch because as you said, it doesn't catch the situation where the tranny is in neutral. So, given the choice of either telling the ecu the phantom 4eat is in drive or neutral, I prefer to tell it is in neutral because this prevents the random high idle problem, and it allows the aux air controller to function properly (allowing proper idle speed when the engine is warming up).

[longassname]

The ECU often cuts fuel during decelleration. It does this with the automatic transmission and it isn't prepared for there to be a manual box there instead of an automatic. This is why you have to send the neutral signal to the ecu when you press in the clutch. If the ecu cuts fuel during decelleration while you are in gear the car will not stall because the drivetrain continues to spin the engine. If the ecu cuts fuel while you have the clutch pushed in or while you are coasting in neutral the engine will instantly stall.

Everyone can debate what they think is happening based on their experiences forever and a day but what I am telling you is a fact not a debatable point. If you want to fix your stall problem you need to start with wiring your ecu correctly. If you still have a stall problem after your ecu is wired correctly then take the next step and put in a dash pot.


So, if the ECU thinks the phantom 4EAT is in D, it will cut all fuel when the throttle is completely closed. If it thinks it is in neutral, it won't. So, if the scenario for, stalling is push in the clutch, change gears, but do not immediately let out the clutch, because you're busy turning, then you would get a stall if the ECU thought you were in D, because it would shut off all fuel when the throttle closed. If it thinks you are in neutral when you push down the clutch, it will see the elevated rpm's that you had when you pushed down the clutch, and will try mightily to get those down to idle, because the throttle is closed. If it tries too hard, by cutting fuel the car will stall. So, it seems whether the ECU thinks the car is in D or N, we will have a stallling situation. Practically, since this period of delayed clutch re-engagement is typically in the range of a couple of seconds, mechanically delaying full throttle closure would solve it, at least for me, with my driving habits.

[longassname]

You need to recheck your wiring then. The nuetral signal to the ecu does prevent the fuel cut. I logged it last night. I checked it 3 times. I decelled and caused the fuel cut sending the wideband to flatline at it's max of 22 to 1 and then put it in neutral which instantly returned the wideband to 14.7 to 1.

If you are using the old ground source for the inhibitor switch from pin 4 as your ground to send to the neutral pin that may be your problem. It looks like that wire recieved it's ground source from the tcu which you wouldn't have anymore.

I know that. If neither the park pin nor the neutral pin are grounded, then the ECU thinks the phantom 4eat is in drive. That's what I meant.

Under decel with the neutral pin grounded and with the tranny in gear, my LM-1 display shows 20.9% oxygen (which is a full lean condition). It doesn't start indicating the presence of any fuel until the rpms get pretty low. That's why I'm curious about your statement about there being no fuel cut during decel with the neutral pin grounded.

I don't see a point in wiring the neutral pin into a clutch pedal switch because as you said, it doesn't catch the situation where the tranny is in neutral. So, given the choice of either telling the ecu the phantom 4eat is in drive or neutral, I prefer to tell it is in neutral because this prevents the random high idle problem, and it allows the aux air controller to function properly (allowing proper idle speed when the engine is warming up).

[huck369]

You need to recheck your wiring then. The nuetral signal to the ecu does prevent the fuel cut. I logged it last night. I checked it 3 times. I decelled and caused the fuel cut sending the wideband to flatline at it's max of 22 to 1 and then put it in neutral which instantly returned the wideband to 14.7 to 1.

If you are using the old ground source for the inhibitor switch from pin 4 as your ground to send to the neutral pin that may be your problem. It looks like that wire recieved it's ground source from the tcu which you wouldn't have anymore.


I wired a position switch in to my clutch that told the ECU it was in neutral when the clutch was depressed, this made you depress the clutch to start the car, and would kick the cruise control off when the clutch was pressed....and I never had the stall problem....

just thought I'd throw it out...

[oab_au]

The ECU often cuts fuel during decelleration. It does this with the automatic transmission and it isn't prepared for there to be a manual box there instead of an automatic. This is why you have to send the neutral signal to the ecu when you press in the clutch. If the ecu cuts fuel during decelleration while you are in gear the car will not stall because the drivetrain continues to spin the engine. If the ecu cuts fuel while you have the clutch pushed in or while you are coasting in neutral the engine will instantly stall.

Everyone can debate what they think is happening based on their experiences forever and a day but what I am telling you is a fact not a debatable point. If you want to fix your stall problem you need to start with wiring your ecu correctly. If you still have a stall problem after your ecu is wired correctly then take the next step and put in a dash pot.

Fact?
Sure the fuel is cut on overrun, but it starts again when the rpm get to around 1200 or so, does on every other car I have seen. How is this going to cause the engine to stall?

It's stalling because the IAC is shut.

Harvey.;)

[mbtoloczko]

You need to recheck your wiring then. The nuetral signal to the ecu does prevent the fuel cut. I logged it last night. I checked it 3 times. I decelled and caused the fuel cut sending the wideband to flatline at it's max of 22 to 1 and then put it in neutral which instantly returned the wideband to 14.7 to 1.

If you are using the old ground source for the inhibitor switch from pin 4 as your ground to send to the neutral pin that may be your problem. It looks like that wire recieved it's ground source from the tcu which you wouldn't have anymore.

I'm grounding the neutral pin directly from the ecu. The "N" light on the dash lights up, and as I said before, the idle characteristics and the cold start characteristics are different than when the neutral pin is ungrounded.

Maybe we are intepreting the fuel cut differently. When I say that my LM-1 goes full lean, this is during decel with the tranny in gear. If I push in the clutch during decel and let the rpms drop, then the afr will go to stoich.

At any rate, I think it would be good if the IAC behavior could be modified. Was hoping you might do some research into the feasibility of this.

[Earthworm]

My car would never stall as long as the A/C was running.

[mbtoloczko]

My car would never stall as long as the A/C was running.

It definitely happens less frequently for me when the A/C is running. I think the higher idle rpm gives more of a cushion for the rpm undershoot.

[TomsSVX]

I have realized something lately, My 6mt has begun to stall now that I replaced the SIAC hose that was dry rotted and cracked. This is further proof that the engine is not getting enough air. You can argue all day that the ECU is cutting fuel but in reality it is still a lack of air that is causing the actual stall. Does anyone have the part# for summit's dash pot? I am gonna order it and finally try to put this trivial matter to rest

Tom

[shotgunslade]

Tom:

Here it is: HLY-11-4

I'm reading all this about how the switch that is made when the clutch is depressed is supposed to tell the ECU that the phantom 4EAT is in neutral, thus preventing stall, and I'm thinking that my neutral is hard-wired, and it is still stalling.

[TomsSVX]

I know, thats why I feel regaurdless of your wiring, the engine will still stall

Tom

[longassname]

I'm going to unsubscribe from this one. Good luck guys.

[TomsSVX]

listen, just being practical. Read into it and over engineer a solution all you want but in the long run it comes down to air being there to burn or not. If there is no air to burn, what good is anything else?? Now rmjjenson was onto something with the A/C being on but not running the compressor. I think that the IAC opens further and the fuel is bumped to raise idle. What we need is the same amount of fuel but a little more air. The Dash pot should cure this stalling problem by allowing the idle to settle slowly and keeping enough air in the engine for it to run.

Tom

[Phast SVX]

I checked tonight, and have my setup wired as lan has described. I have never experienced any stalling. I have a legacy 19lb flywheel. I dont see why we wouldnt all be haviing this problem..it must be something small

phil

[SilVerXtc]

I've never had a stalling problem with my 5mt. But Mine always idles at around 1000-1100 rpm. Acceleration is sluggish untill it hits 2000rpm then it feels like a turbo kicking in or a shot of nitrous(but I think having no cats is the reason.) I'm also only getting about 17mpg. And my cruise control has never worked since having the manual transmission.

[svxcuseme]

See above ------^

[svxcuseme]

I have occasional stalls since the swap. But I had occasional stalls before as well. I think mine may be related to a dirty manifold, IAC, and throttle plates. I'll let you know after cleaning this weekend.

Agree with Tom about the air issue. Did'nt want to say anything because you guys have been working on the SVX's much longer then me. A simple & cheap way to let more air in is to adjust the throttle cable to open the throttle plates ever so slightly. Opps! apparently this does'nt prove so effective, i've even tried to adjust the idle at the engine with the throttle cable and still no avail. I don't see why not though. I've done this with smashing success in my other scoobies.

Edit: Top Clutch switch is wired into NSS, so ECU is aware of Neutral when Clutch pressed. 2002 WRX 5mt with stock flywheel.

[rmjjensen]

It dawned on my a little bit ago and I'm curious:

Has anyone tried wiring the Engine Torque Control signal of the ECU to one of the clutch switches so that the ECU cuts back during shifts? I know it cuts 3 cylinders, or reduces timing, or both....BUT ...if the engine is disconnected from the drivetrain it should still be able to free-rev perfectly fine so you can shift properly at redline ...

maybe ..who knows.

So has anyone tried this? Maybe when the ECU is in its torque control mode the engine won't stall (more control)?

ideas? I might try this but I'd have to wait til next week.

[mbtoloczko]

Here's what I wrote on the torque control algorithm a few years ago:

-------
... Got home this evening and wired a switch between 5 V and the torque control pin. Driving down the road and toggling between open (unreferenced) and 5 V made absolutely no difference in power. Next, I put the switch between the torque control pin and ground. This is where it got interesting. As long as the throttle position was less than about 75%, there was no difference in engine performance between grounded and ungrounded torque control pin. Above about 75% throttle position, the engine would dog dramatically when the torque control pin was grounded. I think it is indeed pulling back timing. ....
-------

[rmjjensen]

i read that and that makes sense for engine performance. ...but what about engine management? That's what we're trying to fix.

I'm talking about maybe the ECU controls the engine differently when the torque control signal goes low (ground). Obviously it does and will harm performance IF the engine is connected through the driveline to the wheels ...won't make power. This is obvious.

But, if the engine is disconnected from the driveline (clutch is pressed) maybe the engine wouldn't bog down at high rpms, and maybe the ECU will be controlling the engine (Idle air control valve) differently ONLY if the torque control signal is grounded.

So press the clutch in, engine isn't under a heavy load, engine torque control kicks in and smooths the engine RPMS, shift into gear, let off the clutch, engine torque control back to normal.

Hey - you never know.

[mbtoloczko]

I don't recall the torque control having any effect on idle (less than 75% throttle), but its been a while. If you want to check, its easy enough to test.

[RisingPhoenix]

My car would never stall as long as the A/C was running.

That's funny.. that would mean it's an vacuum issue that could be resolved with an in line reducer. The best place for one would be between the air box and manifold.
Which reminds me...when I bought my 92' SVX the air box was cracked from air hose to air hose and the Pressure valve had broken nipples I 'Frankensteined' 10 years ago with shoe goo and epoxy. (Along with cracked vacuum lines)
It's high time I check them again...that Pressure Valve I know is beyond shot... :ninja:

[RisingPhoenix]

I still have the 4eat, but I have a similar issue that may or may not be related. Possibly if we figure out one it will be the answer for the other.

When I put my car in park with it idling, and move the selector toward reverse without using the brake or pushing the shift button, the car goes into a high idle. After letting go, it tries to stall. I understand why it would idle high while doing that, but I don't get why it tries to stall. Sometimes it stalls (very rarely) and most of the time the rpms just dip way down without stalling.

Perhaps the two are related and it is not a MT thing. Possibly a computer related issue like you thought.

Agree. The computer is telling the engine to run rich (excessive air) or run less (restricted air) or retard the air, thus, I think a reducer at the Air box might solve this.
Has anyone tried installing a resistor/transistor to any of the transmission wires?
A resistor just may be enough to give that proper 'balance' the computer needs between engine control and transmission. JMT

[SoCoNoHa]

I believe it's already been proven to be the Idle Air Control Valve (not sure if auxiliary or main) that can't open fast enough when the clutch is pushed in and the rpms start to fall. Someone in this forum removed their IACV but left it connected so as not to throw a code, then installed a non functioning valve in its place that always allowed enough air for idle. Boom. No more stalling.

We should be able to do the same thing, maybe with a cheap plumbing valve from home depot, just to make sure the engine doesn't choke when the throttle closes.

I'd love to tinker with this theory myself, but my 5mt swapped SVX just doesn't stall. No idea why but I'll take it :cool:

[huck369]

None of my 5-speed swaps have had the stalling issue....

[SoCoNoHa]

None of my 5-speed swaps have had the stalling issue....

Isn't it strange how some people get it and others don't? Seems to me it's either an electrical issue or a mechanical condition. Basically people don't get the wiring JUST right (missed a ground or something) or a component that's on its way out before the swap starts causing issues afterwords. But what do I know? :confused:

By the way Huck, did they offer the XT6 with a manual or did you have to swap that as well?

[huck369]

Isn't it strange how some people get it and others don't? Seems to me it's either an electrical issue or a mechanical condition. Basically people don't get the wiring JUST right (missed a ground or something) or a component that's on its way out before the swap starts causing issues afterwords. But what do I know? :confused:

By the way Huck, did they offer the XT6 with a manual or did you have to swap that as well?


The XT6 came with Either :
Manual 5-Speed AWD with a center dif lock :)
4EAT AWD
4EAT FWD
So I did not have to swap it.

I think the stalling issue is generally the IAC, the people that have issues with stalling probably had a weak IAC when they had the automatic in, but it wasn't bad enough to be a problem, but with the manual it is more noticeable and causes the stalling problem....but that is just my Theory on it..