Confirm MAF failure?

[Cailean]

I've done all the searching and reading about MAF, smoke and low power that I can - I just need your help to pull it all together.

Symptoms:

• lots of black smoke under medium/hard acceleration.
• lack of power in the upper range. (not limp mode - dealt with that last year with a new N75)
• unplugged MAF solves smoke issue but still low power

I think I've distilled that this means my MAF is dead - though I'd prefer to confirm that before I shell out $200 for a new one. Is it possible that the smoke and power issues are two separate things?

I haven't had a chance to do the VAG-COM tests but will do that after work today...

 

[rdkern]

How updated are you on maintenance? Air filter in particular.

Intake clogged?

How long as this been doing this? Did it come on quickly or gradually?

You can try cleaning the MAF, since ours are more robust than the wimpy film-type on the A4's.

How about egr? Per another thread, our egr's are getting old. You still have one? Might want to consider a block-off plate to test it.

 

[Cailean]

Thanks, rdkern... I haven't been able to reply since I was locked out of my account for some reason...

Anyway to answer your questions:

Air filter looks fine - but I'm going to replace it this weekend anyway.
Intake clogged? I don't think so. Not noticeably, anyway.
Haven't tried cleaning the MAF, nor have I tried a block-off plate.

Here's an update of the symptoms I've noticed.

I've been driving for about a week with the MAF unplugged. Available power has been steadily declining. I can make it go into 'limp mode' if I really try, but it's a barely perceptible drop in power.

If I plug the MAF back in, I get a slight increase in power, 'limp mode' is still possible, though more noticable. Oh, and there is so much black smoke that cars literally disappear behind me...

Should I just replace the MAF?

 

[DanG144]

Have you cleaned the snowscreen?

I would not replace the MAF yet.

Doesn't black smoke mean excessive fuel for air?

How long since you cleaned your intake of carbon sludge? To check this you would have to pull your EGR, or look down into your intake in some other way.

DanG

 

[aNUT]

The first thing I would be looking at would be actual vs requested MAP.

Do you have access to VCDS in order to gather this data?

What codes do you have? I'm sure one is from the MAF being unplugged, but there may be others.

The A3/B4 MAFs are not failure prone like the A4 MAFs.