406oc.co.uk

Hi everyone got a strange one here .For the last couple of days the car has been running itself without my foot being on the accelerator the revs stay up until I come to a complete standstill then the revs will go back to normal idling speed .If I knock it out of gear and freewheel the revs stay up not too high but just enough to notice theres summat not quite right any suggestions thanks .....Rob

If yours had been a diesel I would have said to check that your oil isn't overfilled, but as yours is petrol I would firstly check that the accelerator isn't sticking and clean out the throttle body with carb cleaner or brake cleaner.

Try this first then take it from there.

Thanks for the reply Jasper the accelerator doesnt seem to be sticking but I will investigate further and clean the throttle body and see what happens .I first thought about the stepper motor but the revs arnet erratic

Ah, not running, revving. The HDis do that, something to do with the ecu sensing the car is in motion so not expecting to idle. What sort of revs are we talking about here?

Hi mate, had the same trouble too. Can you reduce the throttle cable clip by one notch and see what happens.....?
My Hdi clip was a fraction too close to the throttle body, made it rev all over the place.

steve_earwig wrote:Ah, not running, revving. The HDis do that, something to do with the ecu sensing the car is in motion so not expecting to idle. What sort of revs are we talking about here?

Dont know as my rev counter is stuck but enough to run the car at 30mph on a level road

Being a petrol I'm a bit in the dark, do they have a cold start on them? If so a dodgy vacuum switch could account for slight over revving?

that's gotta be more like the throttle cable or assembly sticking with the engine running check the throttle fully returns under the bonnet.

Op,

Have you cleaned the Stepper Motor?

Ikenna

As above, stepper motor went on my old D8 petrol, made a right mess of the idle speed. Never did run right afterwards, even when I did replace the stepper.

Check the throttle pot connector. IIRC the failsafe mode of operation is a fast idle which varies after you blip the throttle (1500-2000rpm on the V6)

This is a problem that should be quite easy to figure out if you can get it hooked up to PP2000 (persistent engine ecu faults and/or live reading of TPS, ICV and temperature parameters)