MAF sensor replacing Audi a4 1995 1.8

[AlecTPR]

I've had my audi a4 for about 6 months now and it's idle has never been right, but has got worst in the last couple of weeks.
I've read on the internet several places about cleaning the MAF sensor which fixes it, but, I don't have the courage to take it out, clean it in alcohol and dry it for 24 hours (or whatever is required)
Anyway, I've ordered a new MAF sensor which is coming tomorrow.
It looks an easy swap. Is it standard socket set stuff or do I need any audi specific tools.
your advise is much appreciated.

[miko84]

Hi.
MAF sensor is easily replaced. 1 electronics connector, and four 10mm nuts (as I recall). You will need to remove the top of the air box, and remove the pipe that goes into the MAF, but apart from that it should be a 10min job.

One thing to bear in mind is that its not only the MAF that can cause idling problems... Also check all air pipes to make sure there are no leaks, and if that's ok, then consider having the throttle body cleaned.

Hope it helps.

[AlecTPR]

I was thinking of giving it a clean with isopropyl alcohol but thought, not worth the hassle so ordered one from a nearby trustworthy shop.

I picked it up the other day and had it in the boot waiting for a dry day, which came today. Thanks for the advice about the work needed. You were right, only a 5 to 10 minute job. Problem is, is't still not right so it may be a case of checking all the hoses like you mentioned.

I assume the throttle body is at the other end of the air pipe to the MAF sensor. This looks a little more complicated than the MAF but I think I'll be able to do it. Thanks again for the info and I'll post a reply asap.

[miko84]

Hi, you're welcome.

Word of warning though, if you attempt to do the throttle body yourself, is that when the throttle body is put back in, it NEVER goes in the same place, and the ECU needs to be calibrated bvia the VAG COM interface. TThis needsto be set to basic setting 98. If you dont do this, every time the car approcahes idle it could well stall, since the computer thinks the throttle body is in a different position.
If you can calivbrate it, then it's not too much of a job, otherwise, best to take it to a garage.

Removing and refitting the throttle body is not a major issue, and you are right it is at the other end of the pipe.

Good luck!

[AlecTPR]

I've checked as many of the hoses as I can and they look okay, although this does'n't mean that it's not a hose.

Your right about the throttle body replacement being a garage job. Thought that when I looked at it that it might need something else.

My only concern is that I seem to be throwing a few pennies at this car.
I was hoping the MAF sensor would of been a quick fix. Obviously not and should be noted to all with similar issues the same.

I'll keep you posted.

[miko84]

yeah I know what its like... But to be honest, unless there is something crtitcally wrong (unlikely, since the audi engines are pretty much bulletproof), then the only things that can cause idling issues like this are the ones mentioned before.

This problem can be caused sometimes by the lambda sensor, but this will show up on the MOT, so I wouldn't do anything about it just yet.

Try this... get the car nice and warm, go about 25mph in second gear, then floor it all the way up to redlinne. If you get any flat spots in acceleration then the problem has to be either MAF or split pipe.
If you dont have any flat spots, then it is only an idling issue, and the throttle body is 99% likely to blame.

If you have the VAG COM, then you can measure MAF and lambda, so that should remove some uncertainties.

[alinux]

Hi
I know it has been some time..did the MAF replacement fix your IDLE issue ?
Thanks

[miko84]

Hi Alinux,

The MAF replacement helped greatly with the problem. The MAF wasnt working properly. Although as you can see from other posts, there are other things which can cuase idling issues.

ANY leaks in the air pipes before and after the throttle body will cause the the idling to be out. I have found that it needs a complete seal on all connections.

If you have had your throttle body cleaned, then check the seal which sits at the end of the big air pipe, as it connects to the throttle body. This seal is incredibly tight, and when it's put back it can bend, so although it looks from the outside as if the air pipe is connected properly, the seal could have an air gap. This happned to mine, and by replacing the MAF, getting the throttle body cleaned, and makingsure that this seal sits correctly, ALL my idling problems were cured.

Dont forget the Lambda sensor can also affect performance, and idling, but the MOT should show whether it's working ok, or not, so you can rule it out fairly easily.

Have you done a diagnostic? if so are there any trouble codes?

hope it helps

Mike

[alinux]

Hi
I will have MAF cleaned next Saturday and I will re-clean the TB there are no error codes and I had my system scanned but since this does not happen all the time the scan did not reveal any problem. Could you possibly send an image about that seal that I need to look at ?

[miko84]

Hi Alinux,

Unfortunately I have sold the car about 2 weeks ago, but I had a picture of the engine bay. I dont know what engine you have, but the one I had was the ADR 1.8 20v.

I have made up a pitcutre from what I could find... If you give me your email adderess I will email to you, cos it wont let me upload from my computer.

Basically the big air pipe that goes to the throttle body has a o-ring type seal on the insde edge of it, made of rubber, on the pitcure point number 2.

The air pipe including the seal would fit OVER the thrttle body (on the outside) on point number 1.

Now sometimes when you insert the pipe, and especially on the adr engine, cos there isnt much room, the seal may not go over the throttle body, and might bend and jam inside the airpipe. When it is fully tightened up of course, it wont go anywhere, but it could have an air leak, which causes all sorts of problems.

For the MAF, I would suggest doing some live readings, you can us VAG-COM for, and it will usually tell you the specified and actual MAF readings...

Dont forget that if you clean the throttle body, then you will have to reprogram the basic settings (setting 98).




Mike