MAF hysteria

[Beav]

Just a few thoughts for those of you having issues with your MAFs. Since the MAF is device that measures how much air is actually flowing into the engine at any given time please take a few moments to closely inspect the snorkel tube for cracks, loose clamps, etc. Any air leaks between the MAF and the throttle body will cause the ECU to misinterpret the airflow and cause the engine to operate poorly. I suppose the snorkel doesn't get as much attention as vacuum hoses because most see it as only a fresh air duct.

I've had numerous cars come in for repairs with such leaks, but one still stands out. It was a Camry V-6. The engine torque strut had a bad bushing and allow the engine to pitch back and forth more than normal under acceleration/decelleration. While that's hard on a few items such as the exhaust, etc., it was unduly harsh on the snorkel tube. As a result of the excessive movement it had torn the snorkel in between the bellows.

Here's where it gets interesting: the customer had brought the car in for a heavy surging and stalling problem. What was happening was as they accelerated the engine would tip back and open the split in the snorkel, allowing air to bypass the MAF. This caused the ECU to cut the fuel mixture and the engine would almost stall. When that happened the engine would fall back forward, thereby closing the split in the snorkel and sending the correct signal back to the ECU which adjusted the mixture back where it belonged. With renewed power the engine would tilt backwards, starting the cycle once again.

The point here is that while the initial seat-of-the-pants diagnosis was condemning the MAF, a little closer inspection revealed the true problem and saved the owner some green stuff.

[Ron Mummert]

Now that you've induced my hysteria, just where is that snorkle thingy, & can I get to it without unbolting fifty pounds of metal?

Thanks, Ron.

[Beav]

It's the big black plastic tube that runs from the air filter box to the throttle body. Eventually they dry out and begin to split, etc. That and some people forget to tighten the clamps after removing/installing them, etc.

[Landshark]

good tip, Beav. i just cleaned the exterior of mine with some Vinylex last week, so hopefully it won't crack.

Where is the little sensor that gets gummed up/coated with oil if too much is applied to those aftermarket air filters, and how does one get to it for cleaning? Can you just unclip the filter cowling and bend the snorkel tube? Does anyone have pix?

[Beav]

How about unclipping the filter cowling and loosening the clamp that holds the snorkel to it? That way you can remove it for a good cleaning and not damage the snorkel by making it do things it was never intended to do.