So is the MAF toast?

[87turbolook911]

New '99 c2 owner here...

Over the weekend I noticed when accelerating hard in any gear... once I got to about 5K rpm the car doesn't continue to accelerate smoothly. It sorta stumbles.

So I tonight I pulled the MAF sensor and cleaned it with carb cleaner. The element was a little dirty but not filthy. After letting it dry, I put it back in.

The car seems a bit smoother but the "stumble" is more consistent. Once I pulled into the garage, the idle fluctuated between 500-1100 rpm....almost stalling but didn't.

So is the MAF toast?

[Loren]

Usually the MAF works or it doesn't. Did you look for carbon buildup in the throttle body and idle valve solenoid?

If those are both clean and it still runs the same then a scan tool (that can read) MAF air flow should tell you if the MAF is questionable.

[87turbolook911]

Yes I also cleaned the throttle body/butterfly with carb cleaner....where's the idle valve solenoid located?

Thanks!

Usually the MAF works or it doesn't. Did you look for carbon buildup in the throttle body and idle valve solenoid?

If those are both clean and it still runs the same then a scan tool (that can read) MAF air flow should tell you if the MAF is questionable.

[Loren]

Have a look here for a pic, description and how to clean.

[87turbolook911]

So if I remove the two screws (visible in your picture) the solenoid pulls out? Then just spray and clean out the gummed deposits?

Do I need to remove the throttle body from the car to do this?

This morning I had sprayed the butterfly down with carb cleaner...but not the idle valve....could that have made the situation (idle) worse?

Also is it okay to drive with the MAF asking up the way that it is? Obviously I'm not gasing it hard or racing anyone so no stumble is percieved.

Thanks,

Vu

Have a look here for a pic, description and how to clean.

[Loren]

Well, I usually spray and make sure any deposits are cleaned out. It should move freely when you are done.

You do not need to remove the throttle body to clean the solenoid valve - just remove the valve using the precautions I mentioned.

Did you open the butterfly to clean the carbon build up behind it? If you can do that well on the car then it might be easier to remove the throttle body.

How do you know the MAF is bad? You can disconnect the MAF completely and the car will still run pretty well.

[87turbolook911]

Well I cleaned the solenoid valve per your suggestion, and it seems to have taken care of my erratic idle. Not sure if it has helped the hesitation under hard acceleration. I'll test that tomorrow morning.

I also cleaned the throttle body one more time...this time cleaning everything I could reach in the throttle body.

The car had a PPI done before I purchased and they said the MAF needed to be replaced :(

I thought I would try cleaning it before paying my warranty deductible and giving my car up to be fixed for who knows how long....

Thanks Loren for providing the much needed info.

Vu

Well, I usually spray and make sure any deposits are cleaned out. It should move freely when you are done.

You do not need to remove the throttle body to clean the solenoid valve - just remove the valve using the precautions I mentioned.

Did you open the butterfly to clean the carbon build up behind it? If you can do that well on the car then it might be easier to remove the throttle body.

How do you know the MAF is bad? You can disconnect the MAF completely and the car will still run pretty well.

[Izzy]

Do you know what kind of air filter was in the airbox? There has been some discussion in this forum about K&N and other oiled filters that over time can cause a fault in the MAF. The fix seems to be to clean the MAF filament with an electronic cleaner spray.

Would be another inexpensive thing to try before shelling out the dough for a new MAF.

[87turbolook911]

A K&N type...I'm going back to stock just in case.

The MAF was deemed bad by the dealer...they say it happens all the time...not neccesarily because of the K&N.

Do you know what kind of air filter was in the airbox? There has been some discussion in this forum about K&N and other oiled filters that over time can cause a fault in the MAF. The fix seems to be to clean the MAF filament with an electronic cleaner spray.

Would be another inexpensive thing to try before shelling out the dough for a new MAF.