That does not mean the MAF is faulty.

When you unplug it,computer richens mixture as a safety feature possibly counteracting a vacuum/unmetered air leak.

 

I would monitor the MAF output voltage while moving the flap by hand.

Any defects should be obvious,

 

Cleaning flapper style MAFs is not a common procedure.

Sometimes,the track wears,There is a fix,

Any problem will be easily spotted w/a voltmeter.

Bah, I had assumed it used a wire. I finally got it off of the car, but which pins do I test?

Bah, I had assumed it used a wire. I finally got it off of the car, but which pins do I test?

 

You don`t even need a pinout,

Leave it plugged in and use your voltmeter to find the one whose voltage varies.w/moving the flap.

Main thing to note is the smoothness of the variation.There should be no sudden wonky spots.

 

Never say never,but,a MAF failure seems unlikely.

I had similar symptoms with my 98 Forester (different motor, I know). It ended up being valve related. It started throwing EGR codes. Stray exhaust could cause the computer to call for a leaner mixture, I suppose. 

Here it is starting and almost idling without the MAF sensor connected. It finally warmed up today so I pulled the kick panel off and looked at what codes the ECM blinked. With the MAF sensor still unplugged it gave me 12 and 14, plugging the MAF sensor back in made 14 go away.

12 says stater switch remains off. This doesn't really help with my symptoms, unlike what 13 would have told me... 

Still sounds like a vacuum or unmetered air leak to me.

 

As the Auxilary Air Valve warms up it decreases the idle air supply.

Unmetered air now makes up a greater percentage of the total air thus leaning the mixture to the point of uncombustibility.

I'll look more into vacuum lines, but so far the intake ductwork looks intact and leak-free.

Alright, we feel kinda stupid now. Turns out the PCV valve had disconnected itself from the intake boot. Now it idles properly and responds a lot better. Thanks everyone for your help!

 

..or not. I went out and started it today and it's idling high with the ECS light lit up (wasn't doing this before.) If I rev it the light goes out. It's still only giving me code 12.

Only code 12 with the engine running and ECS light on?

 

Sounds like it could be an oil pressure switch/actual oil pressure problem.

Code 12 with the ignition turned on, engine off. Oil pressure is within the proper range according to the gauge.

You need to check for codes while the ECS light is on and the engine is running.

It gave me code 33 (Coolant temp sensor abnormal), which we suspected Saturday when it wouldn't idle higher when cold.

Hello check your air charge temp sensor its back by the transmission a little to the passenger side (on mine anyways) this little gizmo reads air density and adjusts idle mixture upon start up... sounds like this could be your huckleberry. someone also mentioned earlier about the auxiliary air valve which might be part of your problem too.... a little tip on that, if you take a razor blade or knife to the seam on the black plastic part of the valve you can open her up and adjust it by rotating (clockwise i believe) if you do this your car will idle down sooner... being 30 years old my AA valve's little helio spring didnt wanna move as much as it use to so it was constantly idling high till i adjusted it now it starts @ oh about 1200rpm warms up for about 7 minutes and idles right down to a very awesome 800rpm

oh and i have a part number around somewhere for a air charge sensor that will work with your stuffs as I believe you might beat your head against the wall trying to find the right one at the parts store

The next step seems to be replacing the coolant temperature sensor. I went out and started it five minutes ago and it idled properly, throwing no code 33. Looks to me like it's intermittently failing and is broken.

Edited December 24, 201312 yr by Ziginox

A new symptom; sometimes when I push the clutch in at a stop after it idled high when starting it will rev up and down by itself. Also, the oil pressure reads high whenever it has idle issues. When it runs perfectly the oil pressure is where it's supposed to be.

Oh, I forgot to mention that I did find a vacuum leak due to a loose hose clamp on the bit that goes between the intake and throttle body, and tightening it up cured the leak. However, it's still not running right...

Any news on this issue?

 

John

Yeah, I'm pretty sure I have a vacuum leak to still hunt down. When the engine is cold it will sit at 2250 sometimes, but once it warms up for a while (longer than it would take to drop from cold idle) it will sit at 700. I think it might be a fitting that expands with heat or something, I've just not had time to check, but I might go out there today. I think the oil pressure is just from the temperature.