Audi A4 (1995 - 2000) - yr 1996 - 1.8 petrol engine. Erratic tickover

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Tue 16 Oct 2007 17:36
yr 1996 - 1.8 petrol engine. Erratic tickover - stokie
The revs surge between 1500 and 3000 rpm making driving tricky.
Local garage cleared the fault codes then re-read them, one for lambda sensor (which was renewed a few months ago and emissions are still fine), other is for temperature sensor which he says never manifests as erratic tickover. So he suspects the idle air control valve.

Does anyone have any experience of changing this on a VAG 1.8 petrol?
Is it an easy job? Where is the cheapest place to buy one? Would a secondhand one be OK to get the car running to sell?

Thanks for any advice
Stewart

Edited by Dynamic Dave on 16/10/2007 at 17:40

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Tue 16 Oct 2007 17:58
yr 1996 - 1.8 petrol engine. Erratic tickover - Screwloose
Stewart

Whoops. Never a nice problem on one of these; you could well have a motorized throttle body, not an idle-control valve.

The engine code and the exact age is needed - almost to the day if it's July. You are right on a multiple change point and identifying what's fitted is critical.

If this is a N/A version of the 20-valve then it's likely an ADR or an AFY engine on that year.

I admire your garage's confidence in saying that a failed temp sensor can't affect the throttle - he's a braver man than me. What were the actual code numbers?

Has anyone checked for an air leak?
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Tue 16 Oct 2007 18:12
yr 1996 - 1.8 petrol engine. Erratic tickover - stokie
Good point about the air leak. When this exact symptom occured 3 months ago he fixed it by replacing a split emissions hose somewhere under the manifold. He claims that's still intact. Might try another garage...
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