Mk3 Cavalier Owners Club | Vauxhall Cavalier Dot Com

Car is a 2l facelift automatic. Drives fine, but when you come to a halt with it in drive the engine idle surges up and down so the car keeps trying to pull away. Weird thing is it only happens if i come to a halt whilst in D(rive). If i knock it into neutral before coming to a halt, then the idle behaves fine, sitting at about 800 or so rpm. If when stationary in D i then knock it into neutral, the engine revs immediately rise to 1500 rpm, and then slowly drops back. It's really odd, like there is a link between the box and the idle. So far i've checked the transmission fluid level (ok ) and cleaned the icv. Anyone had this happen before, or got any idea what it might be?

Cheers

Well the automatic gearbox is electronically controlled and does communicate with the engine ECU.
IF it only happens when in drive then I'd imagine that it would be an electrical issue rather than mechanical.

Does it do the same thing when in sport mode or winter mode?

Mm not tried it in sport or winter mode will give that a try and report back, thanks

Got same problem sometimes on my 1.8, idle goes up to 1500 then drops slowly, never really worked out what it was. On 2.0 though I have heard potentially blockage, or dirt/oil accumulation problems around the intake manifold and/or wonky accelerator sensor. Also perhaps check breather system and if you can for error codes using pin technique.

Thanks, was considering breathers so will give that a go too

Hi, been a while as i've been busy with other crap, but had a play around with the cav today, swapped the idle control valve back to the cleaned original, big mistake, idle going up and down for no reason, so back to the replacement and it settled down a bit. Breather pipe from top of the cam cover cleaned out too. The one thing i did spot was there is a 3 pin connector that goes through a thing metal plate bolted to the cam cover. The plug on side that disappears down the side of the cambelt cover has broken into several pieces, it's the side that hasn't got the metal clip on it. I've held it together with duct tape, but can someone tell me what it is, where it goes, and can i replace it?

Also have tried the car in sports mode and it still does it, only way to avoid it surging is to knock it into neutral when coming to a stop and then putting it back into drive when i want to move

Can anyone confirm that the connector that joins at a metal tab attached to the cam cover is the crankshaft sensor, and if so where does it go, as it seems to run down the rear side of the timing belt cover? Cheers

If anyone has a diagram that would be fantastic

Robsey's yer man for diagrams. Got any pics? It might help those of us unfamiliar with your car in our efforts to offer advice.

yep, just signed up to photobucket for that very reason!



The lead looks like it goes down the rear side of the timing belt cover, and goes inside it, but i can't see where it goes after that

Yep, the connector on the metal tab is the crank position sensor. The sensor itself is in the Front of the block, left side when you look at it. Was a hard job on the GTE, because of the power steering pump. On the Dippy, it looks near impossible, behind the PS pump and AC compressor. If you have an AC car, good luck !

My gut feeling is that it's around the ICV... I was having idle issues with the NE in my GTE, the guys from Mig, helped me narrow it down by unplugging the ICV, which puts it into failure mode, and it fails open, at the correct opening to give 1500 rpm.

Check the large air hose from the airflow meter to the throttle body too.. Make sure theres no splits..

The crank angle sensor lead goes down the back of the engine undernearth and part way back up the front.

From memory it travels between the timing belt cover plastics.

Regarding idle control valve or air flow meter issues.
If you unplug either one, the car will still start and run in "default" settings mode.

The engine light will illuminate.
But try running the car with one sensor disconnected at a time.

If the running issue eases, then the disconnected sensor will be your potential culprit.

A further thought on the crank angle sensor...
If it is faulty, or it's connections - chances are that the car would not run at all.

Any issues at idle are usually air and fuel controls or leaks.

Electronically these are controlled by the air flow meter and idle control valve or throttle position sensor / switch.

Mechanical issues
Air induction - leaking vacuum pipe, air induction hose, air leak into throttle body gaskets or clogged / oily breather pipes.

Fueling - worn or sticking injectors or worn fuel pressure regulator.
Is the throttle cable sticking or set with no slack in the cable.? This can cause a high tick over.

thanks for the advice i've got a new crank sensor ordered and will have another look over the weekend

cheers

Been a while, but i've fixed it...sort of. The big air hose was split, so swapped that and also swapped the crank sensor, but now when cold and not in drive , if i rev the engine, it hits around 2500rpm and the eml light comes on, and the revs drop, and then the eml light goes out.
I'm hoping it's not the new sensor as it was a pain to swap, but not sure what else it could be? Car drives fine when warmed up and in gear.