[prospectmotoring]

I have a 1997 A4 1.8T FWD. The idle on it oscillates up and down when I take it out of gear while coming to a stop. Sometimes it will die and others the idle goes down to the point where the lights go dim and the engine shakes. When I come to a complete stop and let it idle, it is fine. The other day the speedometer stop working and light magic the idle was fixed. Now the speedometer works again and the idle problem is back. Any ideas?

 

[RickT]

I have moved this post to the A4 B5 section as you will get a better response compared to Technical > Performance

Cheers

Rickt

 

[Chris555]

I had exactly the same problem recently on my car as well - It happened shortly after i'd beed through a car wash - it turned out to be the idel control sensor - it had got damp and basically everytime i lifted of the accelorator the engine dropped to zero revs and died - i had to left foot brake and keep my right on the accelorator to keep the engine alive - a right pain in the backside - i had it cleaned and it has never been a problem since, and the engine idles perfectly now at 975rpm. I thought it was going to be a big problem as everybody was suggesting my throttle body may need cleaning or to be replaced but as it turned out it was a very minor problem and easy to sort - hope this helps

 

[prospectmotoring]

Thanks, I'll give it a try and see what happens.

 

[flp_szymanski]

Exact same thing happens to mine. Maybe the Idle Air Sensor or maybe not, this is what I assume. Anybody have any info on this problem? My happened after serp belt was replaced. Also my volts gauge drops to about 12.5 or just dies when this rev problem occurs and increases to 14.5 as my revs go back to normal at 600-700. I thought it may be a bad alternator but pretty sure it's not.