Thread: High Revs When Idling :confused:

Over the last few weeks when I start my Disco's engine (3.9l V8i) it idles at around 2000rpm. This used to be a sporadic thing but now it is almost every time.

It happens both when the engine is running on LPG or petrol.

I've checked the throttle cable etc to make sure nothing is sticking there and everything looks good and seems to work okay.

So, what could it be? What else should I check?

Also, and I don't know if this is connected with the above, after a good run out when I stop for traffic lights or whatever the engine likes to pretend it's about to stall and then picks up again over and over. But, it only does this on Petrol. On LPG its fine.

Otherwise, when driving my Disco runs fine on petrol or LPG and certainly doesn't hang around once I put my foot down

Thanks in advance!

Originally Posted by sam_d

Thanks for the replies!

Is cleaning the stepper motor/air idle control an easy straight forward job (for someone with little mechanincal experience)?

I'm going to try this before looking at the coolant temp sensor as after having searched for and looked at other threads regarding "stepper motors" I think this is likely to be the culprit.

Cheers,
Sam.

Just unplug the electrical clip. Unscrew the stepper and squirt some carby cleaner on it and into the hole it came out of. BUT DO NOT UNDER ANY CIRCUMSTANCES PLAY AROUND WITH THE STEPPER< LIKE TRYING TO UNSCREW THE PIN!.
When clean, refit with a new washer and plug back in.