Over the last few weeks, my idle began to fluctuate a bit, and as I slowed down / pushed the clutch in, it would dip several hundred rpm too low before returning to idle. It's also felt slightly "jerky" at low speed when running from cold - for the first 30s or so. On Saturday, it decided it had warned me enough and stalled 3 or 4 times.

Many of the parts that could cause this are new (coils, dist. caps, rotor arms, plugs) and I also swapped the air flow sensor recently. On Sunday morning I decided to rule out the obvious stuff - I performed a DME reset, I cleaned the air flow sensor and ISV.

Sure enough, on Sunday the car ran perfectly, the idle is now rock steady and there is no dip - it just drops straight to idle and stays there. The car runs perfectly from cold and is pulling strongly.

But...... the idle is too low. It's idling at about 790rpm. In all other ways the car runs perfectly, and if I didn't know any better I'd say there was nothing wrong with it. But the idle is clearly lower than it should be.

I've just pulled the DME relay and am going to go out for the 15 minute run now. Not sure if this will raise the idle again. I know the idle speed is controlled by the DME - I can't understand how it can have been too low. Especially when in all other aspects it seemed to be perfect!

Any ideas?

 

The Hammer has an idle adaptation function which should be able to set the idle for you.

Doing a batery reset does not always sort it out.

Erratic behavour may indicate there is a vac leak or the ISV is on it's way out.