Odd tickover problem?

[ropeman23]

2.1 WBX

This doesn't happen all the time, it goes through patches of doing it. The van will normally tickover at about 1000 - 1100 rpm, but sometimes I'll pull to standstill and it'll be ticking over at 2000 - 2100 rpm. When it's ticking over this quick I can put it in gear and start to realase the clutch, without touching the gas pedal the revs will drop (as you'd expect), if I engage the clutch again it'll now tickover at the lower rpm. If I re-engage the clutch at say 1500 rpm it'll tickover at 1500 rpm. If I re-engage at 1000 rpm it'll tickover at 1000 etc. etc. Anyone else had this before?

Any ideas?

[syncrosimon]

Your 2.1 needs to be ticking over at 800 rpm. Re set it by turning the big slot screw near where the throttle cable attaches.

See where you are after that. Being set too high will un balance the idle stabilisation crontrol unit.

Simon.

[ropeman23]

Hi Simon,

I've tried setting the tickover as per the Haynes Manual, but 1000 - 1100 is as low as i will go, sorry I should have mentioned this before.

Phil

[ronsrecord]

could the idle bypass valve be stuck?

[ronsrecord]

also - look at mattk918's brilliant posts on iscu failure etc.

[syncrosimon]

If you cant get the idle down lower then either your engine temp sensor (plug in one with two wires) is telling the computer that the engine is cold, your iscu is being told that the power steering is activating, or more likley your throttle body is worn, and is allowing air through.

Hold your throttle arm and wiggle it, there should be no movement. They are of a poor design (well for lasting more than 20 years) and wear in the shaft allowing air through and raising the idle.

Simon