Hello,
I have a friend who has a reasonably new 1.8 Vectra (around 3 years old) - it has developed an intermittent fault with the idle speed. Periodically whilst idling the engine will start to rev itself from normal idle speed to somewhere between 1,500 and 2,000 rpm, exactly as though the driver was pumping the accelerator peddle. No engine management warning light is shown, so presumably no fault codes are logged.
Any ideas?
I was thinking somewhere along the lines of crankshaft sensor... but I'd appreciate some advice.
Kind regards,
Cyrill666
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Much more likely to be the idle speed control valve. That and the throttle butterfly area get dirty due to intake of crankcase ventilation fumes. Common problem. You can sometimes get away with cleaning the item, but it may have to be replaced.
Regards
John S
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OK, thanks.
My Haynes manual is at home... in terms of access, is it a straightforward job getting these components out of the car and cleaning them? What cleaning agent do you recommend (I'm aware that some components are particularly sensitive and can be damaged easily)?
Failing that, does anyone know the approximate replacement cost of a idle speed control valve, or throttle butterfly mechanism?
Kind regards,
Cyrill666
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cyril
You won't need a new throttle butterfly, because these can definitely be cleaned. If the ISCV can be cleaned, then fine, but it doesn't always work. Replacement is about £150 at the dealer - iscv £120ish plus half hour of labour.
The ISVC is held to the side of the main throttle butterfly by a couple of Allen screws. Clean with the usual oil/grease solvents, but the Tune-up crew suggest you hold it so they don't run back into the actuator.
Theres a mod (cheap) available for the crankcase vent pipe that's supposed to reduce oil carry over, which the Vx dealer should know about.
Try a search on this site, as it's come up fairly regularly.
Regards
John S
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My Rover Turbo suffers from a similar problem, generally known as "oil pull over". The throttle body gets as black as the ace of spades in about 10k, depending on how the car is driven (dirtier quicker if driven hard). I remove the throttle body from the car every 12k service and thoroughly clean it with carb cleaner and an old toothbrush. At every 6k oil change it gets a minor clean whilst still on the car. Makes quite a difference to the economy.
The other problem is also that the oil droplets that form the film get forced down the MAP sensor pipe by the turbo pressure. If it gets bunged up the sensor cannot measure the manifold vacuum. Be worth checking this - clean out with carb cleaner - BUT DO NOT get carb cleaner in the MAP sensor.
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I had this problem on my 2.0 SRi and it was the eventual reason I got rid of it last Spring. Vxhl were unable to resolve problem - their cust service was s***e - and they advised me to take apart the idle control sensor and clean it (some sort of piston affair). Followed their instructions - took apart air mass sensor instead, which was in location relayed and fitted description given. £300 later, I STILL had to deal with the idle control, and basically couldn't be bothered.
In my opinion Vauxhall should have sorted out this problem before the car hit the streets. Hassle Vauxhall to repair it themselves. Mine was a pain to diagnose without paying thru the nose for them to look at.
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PS It is not the crankshaft sensor. That was one of the first things to go on mine, and when it goes it stops the engine going over about 4000. It certainly didn't fluctuate as you describe.
Your symptom is Idle Control Valve Sensor.
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As John S says, doing a search of this site should bring up detailed help on how to clean the ISCV.
I also seem to recall that the cavweb.com (cavalier, vectra owners forum) site has this topic well covered.
I have a friend with a similar symptoms on a Cavalier 1.6L and I will post its own new thread.
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