Stepper motor again

[edhorne]

Hi all

I know this has been done before but I couldn't find the exact answer in the archive.

With the stepper motor removed should switching the ignition on cause the plunger to move? Should it move when the ignition is switched off?

It buzzes when you switch off and I can feel it doing something when the ignition is switched on but can't see the plunger moving at all (motor removed). I have cleaned the conical end and the threads in the plenum.

I am investigating a starting problem. The car starts idling at around 500rpm. Then, over a 30 second period the idle slowly builds to normal.

This is the same regardless of engine or ambient temperature.

PS I have changed the Coolant Temp sensor today but no change at all.

I'd appreciate you help on this one.


cheers

Ed

[snorky]

has the stepper got the fibre washer on it - they're quite thick and mine was missing when we refitted one the idle point moved up ... ?

[edhorne]

No I don't think it has got a washer on it. Anybody know what thickness it should be or a part number.

Sounds like that could be it. Not letting enough air into the manifold for idle and then a delay while the lambda sensors put less fuel in ???



Many thanks

Ed

[shpub]

Quite a lot of them don't have a washer or if they do it is quite thin. See the bible piccies on p104 and p85 and you will see what I mean.

It might be worth resetting the base idle because if this is screwed up then the stepper can't control the idle because there is insufficient air available.

[edhorne]

Thanks Steve

I'll have a go at the base idle. I have read it in the bible so I'll see if it makes a difference.

Cheers

Ed Horne

[edhorne]

So...

...I cleaned the stepper and butterfly and then tried adjusting the base idle and whilst it starts much better it now idles at 1300rpm. Bugger

I guess I'll try again.

Should I be worried if the idle screw is almost closed fuy to get 500rpm base idle? Air leak?

Many thanks

Ed

[glynlucas]

Before going any further, I would suggest you reset the ECU by disconnecting it for a few seconds. If it had previously detected a fault, it will have gone into limp-home mode.
Also, it would be worth checking the throttle position sensor. The Bible explains how to do this - you will need a test meter.

Note, resetting the ECU will cause fast idle for a while until it adapts which happens only when the engine is warm.

Hope this helps.

[edhorne]

Thanks for the advice.

I tried again with the engine warmed up but to get 500rpm as base idle I had to close the idle screw fully. Then when I released the bypass hose it idled at around 1200rpm.

Mark Adams reset the idle in the software at my rolling road session last year but I hadn't cleaned the butterfly. I can only think that cleaning this has upset it.

I will try an ECU reset followed by an "adaption" and see how that goes.

Cheers

Ed

[shredder]

I hope to pay Kate this much attention!!!

Hi mate, how are you?

Would be good to catch up give me a call at 208 anytime.

:-)

[ardvaark]

I recently bought a new stepper motor and it has improved the idle and part throttle behavior enormously. I had tested the old one by removing it from the plenum and then turning the ignition on and off. It buzzed but didn't move unless coaxed. The new one moves in and out when the ignition is turned, suggesting to me the old one was partially seized. I took the plunge and bought mine from the local main dealer and it is supplied with a fibre washer.