Vauxhall Vectra 3.2V6

[gina32]

Does anyone know why the idling speed keeps increasing and decreasing on my car please. THANKS

[tonyav]

Don't think there is an idle control valve on that engine, fly by wire if I remember correctly. So if it is fly by wire then it will most likely be the potentiometer which is part of the throttle pedal ( needs a new accelerator pedal ).

[gina32]

Thank you

[tonyav]

Best of luck, gina.
I to have had tick over problems in the past on a couple of Vauxhalls ( Carlton and Calibra ) they had idle control valves though, I just changed them. Your engine is totally different though.

[Hymie]

Is the engine warning light illuminated – even if not, it would be worth plugging in an OBD scanner to see if any fault codes are present.

What is the approximate range of engine idle speed – is the lowest idle speed around 900rpm with it increasing above this level; or is it idling slower than it should and then increasing to 900-1,000rpm (or more)?

[gina32]

I have had it on several fault finding scanners and nothing shows up. It idles at 900 rpm and then builds up to about 1500 then drops back and so on.

[davewr]

I had a similar problem on a Ford that went unsolved by three different main dealers and was sorted by accident when I started using a different garage for fuel. I still use supermarket fuel, just not that one.

[derek-33]

is your air con on. that will decrease it slightly if it is

[Hymie]

It’s worth giving davewr’s suggestion a try – filling up with one of the premium fuels available from a non-supermarket supplier. The extra cost of a tank full of gas will only be £2 - £3.

[RobNorth]

Ensure there are no air leaks around the inlet manifold joint or associated plumbing.

[gina32]

Ive changed the fuel, not leaks as its been changed. so no idea!! Thank you

[Hymie]

Might be worth adding some Redex next time you fill up the tank.

[Hymie]

To test for leaks around the inlet manifold (or elsewhere) spray a small amount of WD40 (or similar) around the area – if the engine increases speed, you’ve got a leak.

Make sure not to spray the lubricant near parts such as driving/timing belts.