low rpm stalling

Hello,

I seem to have a problem that happens about half the time coming to a stop sign or a traffic light. As I slow to a stop it stalls..

Is this a transmission glitch or an idle that is too low. That said, it normally idles at about 500 rpm, which seems a little low to me. Is there an adjustment screw or is this one of those "do not touch" emissions related things?

Thanks for the help

Hotshoe

[mbtoloczko]

Not sure what the problem is, but 500 rpm seems a bit low for idle. I think mine idles at about 750 rpm. My Chilton's manual says that with *all* accessories off, including lights, and the car in "P", it should be between 600 and 800 rpm. It also states that you should check it with a bunch of accessories enabled. It says turn on the lights, AC, and rear defroster. The idle should go to 800-900 rpm.

Before attempting to adjust the idle, the manual says that you should first check to make sure the ignition timing is correct, the plugs are in good shape, and there are no vacuum leaks. Adjusting the idle is accomplished by connecting the "Subaru select monitor" to the harness located under the left side of the dash. Don't have one of those do you? Apparently there is an idle adustment screw, but the manual says not to touch that.

[Mr. Pockets]

When it's warm, the car should idle at around 600rpm. I wouldn't call 500rpm suspicious.

It sounds to me like maybe your idle air control valve might be sticking. The IAC valve in my wife's Legacy was sticky, and the symptoms were similar, but her car also loped a lot.

I'd recommend removing the IAC valve and cleaning it with some carb cleaner and whatever else you can fit in there to scrub off any deposits. Of course, don't leave the scrubbing device behind.

[SVX10]

I had some low RPM stalling when my Mass air flow sensor went bad. Don't know how to test it, but my subaru dealer diagnosed it for free. Maybe do a search on adjusting the TPS since that regulates idle RPM.

[vkykam]

Try cleaing the throttle body first... If it still happens, and you suspect the MAF, I can always loan you mine for an hour... I'm still looking for an excuse for a meet.

Idle without the A/C running and the engine warm is about 600RPM.

Oh, and look for a vacuum leak too, especially along the hose from the MAF to the throttle body. I found two cracks on the air box attached to the throttle body, and the cracks were where the various hoses attach to the air box.

BTW, I saw a silver a few days back in TO (along with 3 other SVXes that day, but I was driving my Legacy ), with a Barrie Auto Group (or something-or-other) license protector on the back. Any chance it was you?

VK

Originally posted by hotshoe50
I seem to have a problem that happens about half the time coming to a stop sign or a traffic light. As I slow to a stop it stalls..

Is this a transmission glitch or an idle that is too low. That said, it normally idles at about 500 rpm, which seems a little low to me. Is there an adjustment screw or is this one of those "do not touch" emissions related things?

[Beav]

Originally posted by SVX10
I had some low RPM stalling when my Mass air flow sensor went bad. Don't know how to test it, but my subaru dealer diagnosed it for free. Maybe do a search on adjusting the TPS since that regulates idle RPM.

No, the TPS doesn't regulate the idle.

No, you don't adjust any screw(s) to raise/lower the idle. The only screw available is the throttle stop and it's only to keep the throttle blades from digging into the throttle body. Messing with this screw is a Bozo no-no.

A vacuum leak will raise the rpm just as if the throttle were opened a bit. However there's usually a roughness added as a result.

The ignition timing is adjusted by the computer. As the SVX has no distributor there's nothing to adjust.

Nick's got the right idea. Do a search for cleaning the throttle body and idle air controller, that should be the cure. While you're in the vicinity replacing the PCV valve is a good idea.

[svx_commuter]

Beav,
So what sets the idle speed on the SVX? ECU?
Are the throttle plates normally a little bit open or completely shut?
What happens if the screw backs out a little?
Surely if the screw was turned IN the idle speed would go up or is there some other problem with that?

[dromano]

Originally Posted by Mr. Pockets

When it's warm, the car should idle at around 600rpm. I wouldn't call 500rpm suspicious.

It sounds to me like maybe your idle air control valve might be sticking. The IAC valve in my wife's Legacy was sticky, and the symptoms were similar, but her car also loped a lot.

I'd recommend removing the IAC valve and cleaning it with some carb cleaner and whatever else you can fit in there to scrub off any deposits. Of course, don't leave the scrubbing device behind.

Where is the IAC located? I have a low idle rpm issue, started a few weeks ago. I cleaned the MAF & new spark plugs on Sunday. Next I'll go after the PCV valve, what a PITA that is, I have a set of crow's feet now so might be a bit easier to r&r.

[Cam]

Originally Posted by hotshoe50

I seem to have a problem that happens about half the time coming to a stop sign or a traffic light. As I slow to a stop it stalls..
Hotshoe

Do yourself a favor and clean your MAF. Easiest thing to do and it is a likely culprit. Just buy some MAF cleaner (don't use anything else) and spray the crap out of it, let it air dry, then reinstall it. If it doesnt work unplug your battery for an hour or so to reset the computer and see if that helps.

[dromano]

Originally Posted by Cam

Do yourself a favor and clean your MAF. Easiest thing to do and it is a likely culprit. Just buy some MAF cleaner (don't use anything else) and spray the crap out of it, let it air dry, then reinstall it. If it doesnt work unplug your battery for an hour or so to reset the computer and see if that helps.

Thanks for the info, cleaned the MAF a few days ago, new spark plugs Sunday. Engine still dies in drive at a stop, I look at the tach & it's 500 or less, if I put it in N it picks up enough to keep running. I'm going to clean the PCV valve next.