100e 2.0 Erratic idle - have cleaned the ISV.

Posted: Thu May 29, 2003 2:23 am

Car is a 1992/J Audi 100e 2.0 estate.

On start up from cold seems to idle low 600rpm, and then rise slowly to 800.

Then, once fully warmed, say arriving back into city roads after a motorway run - it either idles @ 1000rpm so quietly you can't hear the engine.

or - there's a regular pulsing noise/ strong vibration that can be felt through the car, this idles at about 1050, with very slight movement from the rev counter.

- dab the throttle and this pulsing and noise goes.

So far -
Cleaned the ISV with carb cleaner ( left standing full overnight ).
Then Left to dry overnight in boiler Cupboard.
Fitted this morning - car started but then wouldn't idle at all - would every time came to a standstill ( rev counter falling evenly to zero. )

But - after 2 miles of town driving idle back to normal symptoms, so no stalling and it seemed actually improved from the pre-cleaning symptoms

but - after 1/2 hour journey the old pulsing noise/vibration had returned exactly as before.

Any suggetsions for the next try at a remedy?

Thanks Mad

Site Moderator Joined: Jan 31, 2003 Posts: 9144

A pulsing idle is often a sign of a weak or failing battery. The ISV relies on a solid voltage suuply to operate correctly. If the voltage is weak, the ISV will raise the rpm to compensate.

Posted: Wed Jun 04, 2003 8:50 am

Mike,
thanks for the diagnosis - suppose a new battery won't break the bank - I'll test it with a volt meter.

Euro Car Parts - Bosch seem best price.

I was about to post a message saying that topping up the oil ( it was very, very low ) seems to stopped most of the symptoms

however, ....it is taking a fair while to start in the mornings - in line with a battery on the way out.
Thanks again

TimP