Won't idle (intermittant)

[marlboro]

Now and again my Chim won't idle, hunts a bit then stalls. It becomes more of a problem the hotter the car is. Above 2K revs it runs fine. However at times it behaves fine.

Is this indicative of the stepper motor, any other ideas.

[zippy500]

Most probably stepper. try cleaning it with white spirit. it may help. they are about 90 quid.

[Ballistic Banana]

Dont over tighten when you put the stepper back in as it is possible to strip the thread as warned by the ' Almighty' in 'THE BIBLE'

Simon

[grasp]

also check seal before refitting-the other cause is the tune resistor which sits 20 cm up the ecu harness from the ecu(transparent heatshrink with a resistor init and 2 wires from leading to a blue connector)same symptoms-cerberus

[marlboro]

Cleaned the stepper motor and now appears to run fine.

However it was only 'lightly' carbon coated. Is that enough to cause problems? All seemed a bit too easy.

[RCA]

I think so, I regularly clean mine even if there is a thin coat of carbon on it and it always cures my idling problems!!!!!

[grasp]

yes it is -the smallest amount will not let the stepper return fully causing air to seep past

[robperrie]

mine is doing that...where is the stepper located.....

[zippy500]

rear of plenum chamber on the left. It is the thing with a big hexagon shape on it and a bunch of wires. You cant miss it its right at the back.

[schueymcfee]

Mine does the same, but I've put a brand new stepper on. What's this about the tune resistor?

My other thought is the speed sensor.

But before buying one how can I tell if the tune resistor is working?

[GreenV8S]

quote:
Mine does the same, but I've put a brand new stepper on. What's this about the tune resistor?

My other thought is the speed sensor.

But before buying one how can I tell if the tune resistor is working?

This is only one of many things that has to be right for it all to work. It's quite complex and hard to trouble shoot by trial and error, or guesswork. There's also a significant risk that you will damage things while you're experimenting. THere are some quick and simple fixes you can try such as resetting the ECU and cleaning the stepper, but beyond that unless you enjoy spending lots of time and money on the car, I'd recommend a specialist as the quickest and most effective way of fixing this sort of running problem.

Cheers,
Peter Humphries (and a green V8S)

[schueymcfee]

Cheers Peter,

I certainly shall be spending big money when I get back from the US in August, missing it already and I've only been here 2 months.

Funny I don't miss the missus though!