Running Problems after Air Filter

[JohnRet.]

Hi,

Yesterday I fitted a pipercross replacement panel filter.

It was a git of a job getting the airbox open and closed, but after a bit of swearing it went in.

However....... I now have running rpoblems, mainly juddering and flat spots when going through the revs. Car is definitely slower.

Has anyone got any ideas what it might be?

I don't have VAGCOM nor do I have access to it

(B5 S4, no mods, 60k)

[arS4]

straight off I'd be looking at the MAF (Mass Air Flow) meter......

These are alway potential issues with a turbo'd car....

Have a look on here about cleaning the MAF - probably when you changed the filter, you've disturbed some sh1te and it's contaminated the MAF


Hope this helps.

Dan

[S4TAN]

It can be a bit 50/50 cleaning the MAF - 1s time i cleaned mine it was fine - 2nd time it killed it dead! (BTW - if you are going to clean it use >99% IPA: drop the MAF into a sealable bag full of IPA and shake well, DON'T clean it by rubbing the sensor elements with a cotton-bud soaked in IPA!!)

HTH

[shineydave]

i'd be swapping the filter back. it's the only thing that you know for certain has changed. if it doesn't get better then try cleaning the MAF but in my opinion don't fix what ain't broke because it usually ends up broke.

[Doug_S2]

Did you pull the power amplifier connectors removing the airbox? Use some contact cleaner on those and make sure they are connected properly.

[JohnRet.]

I'll try the connectors first, because it's easiest. Then I'll try putting the old filter back in, really don't want to do that agin though....

.... then I'll try the MAF cleaning. does the sensor just unplug from the MAF tube bit?

[Nige_RS4]

.... then I'll try the MAF cleaning. does the sensor just unplug from the MAF tube bit?

I usually take the whole MAF out, spray it from both ends with 99.9% alcohol, leave it to dry and refit it.

As mentioned above, do not touch the sensor!

[maxxximus]

Most likely MAF - theyre always a problem whether youve got NA or a forced induction engine.

Best to clean it as above and then if still causing aggro try running it a short while with MAF disconnected and see how it runs.

[JohnRet.]

Right,

tried the connectors this morning, no joy.

Swapped the air filter back.... no joy.

The MAF is now drying after being sprayed with this stuff

[JohnRet.]

Put it all back together again with the original filter back in and the MAF cleaned.

Definitely better, but still not 100%

[JohnRet.]

And tried it with the MAF disconnected and it's great

New MAF then....

[grizz]

I usually take the whole MAF out, spray it from both ends with 99.9% alcohol, leave it to dry and refit it.

Tut .tut . What a waist...

[JohnRet.]

So if it works OK with the MAF disconnected, is it as simple as replacting the MAF?

Or could it be the actual connecter?

[shineydave]

nope, it'll be the MAF although there seems to be several different failure modes. when mine failed it put the ABS and ESP lights on but drove fine both with it connected and disconnected. others tell of the car being a pig to drive but no lights showing

[JohnRet.]

Yeah, I've got no lights showing, however, when disconnected, the ABS light was on.

If I get a new MAF and fit it, will I need to get any codes reset or will it be hunky dory?