Throttle sticking - S1

[Ferg]

Out for a run last night and the revs are staying high. Thought it was finally my plastic throttle body doing it's thing but had inlet off today and the butterfly is closing fine but revs stating high. Does that then mean the idle speed control valve is to blame? Any suggestions welcome.

I do have a 52mm TB to put on if needed.

Cheers
Ferg

[les]

might be worth resetting the TPS if the revs are high when idling and then taking the car for a quick blat to get the ecu recalibrate

[robin]

Also check there is enough slack on the throttle cable. Don't be tempted to lubricate the spindle with WD40 or similar as this will dry out and leave a sticky residue that will attract grime and actually make the problem worse, not better.

Cheers,
Robin

[philthy]

Also worth checking the rubber vacuum hoses on the inlet for splits

[robin]

If it is high but slowly settles to nearly the correct speed then a vacuum leak on the inlet manifold is quite likely.

If you are also losing a little bit of coolant then the inlet manifold gasket is known to fail on the plastic manifold (I think they changed the gasket to a newer material to prevent this happening at some point).

Cheers,
Robin

[Ferg]

Thanks for the replies. Keeping the car elsewhere while working on the house so will apply said ideas at the weekend and let you know how it goes.

[hiscot]

If you have a non standard air filter check the hose clip has not been changed for a jubilee type I believe they can be over tightened and warp the plastic body

[Ferg]

Yeah, been keeping an eye on that. It's what I thought it might be at the start. The butterfly can be pushed tight closed a little further than where it rests but still the revs should be lower for the air that could pass through the butterfly at rest. Suspect an airleak.

[Ferg]

Update:

So, after researching this further I found that the throttle cable can also cause this. But as I had a 52mm throttle body sitting there anyway I thought I may aswell fit it, and test the simple things before taking on anything too critical. Low and behold it's fixed the issue, or certainly appears to have. I had purchased a throttle cable in case, but havn't had to use it. It appears that the little distance the throttle failed to return was causing the issue. Didn't look right to me at the time, but everyday's a school day.

So have a little upgrade into the bargain which is good. Also swapped out my K&N for an ITG kit which has reduced the induction noise significantly.