Erratic revving at idle...

cleanbluesky · 20 Apr 2007 at 16:58

My A3 1.8T is revving slightly erratically at idle... this happens when either warm or cold, and it is totally stable when I am driving along.

It's a '98, anyone got any ideas?

The Running Man · 20 Apr 2007 at 16:59

how erratically? by 25rpm each way or more?

could be MAF related look around the Audi owners club they will probably know the answer if its common.

cleanbluesky · 20 Apr 2007 at 17:02

I think it idles at 800 and will tip up to 1k when erratic, it will also do so with a slight judder rather than smoothly. Very rarely it might go as high as 1.4k

VBDub · 20 Apr 2007 at 17:13

Sounds like the 02 sensor to me, my fiesta had your symptoms and that was the problem.
My house mate had the same symptoms on her Yaris and it was the 02 sensor too.

The Running Man · 20 Apr 2007 at 17:17

yea mine idles a little rough but no more than 25rpm each way as is symptomatic of a hot wire MAF.

as suggested could be an 02 sensor but i would check the ecu for error codes?

ScoobyDoo69 · 20 Apr 2007 at 17:34

I've read that the VAG engines go like this when the MAF goes..?