steadily climbing idle speed

21st February 2012, 19:07

My 2002 VTR's idle speed is fine when it starts, and is OK for most of my half hour commutes. But occasionally it's a pig, with idle speed at the lights climbing quickly to anything up to 4K revs! This only happens when it's well warmed It's actually OK to drive it away and when driving, so it's not like there's any real power behind the reving. It is difficult to drive smoothly though when its doing it, with the throttle behaving more like a switch.

It's not a stuck throttle cable/peddle (it climbs by itself rather than sticks on) and I've changed the ICV and the MAP sensor with little improvement. I can't see that it's the crank sensor as it never runs roughly, battery is fine and always starts it even in the worst frost. My next step is to take appart the throttle potentiormeter and clean the tracts, but I'm not that hopeful as surely that would be a problem all the time?

Any other ideas?

21st February 2012, 20:12

possibly holes gaps in your air intake messes up your air fuel ration so car auto revs to dump more fuel ... did this on mine was due to a hole im my air box

21st February 2012, 23:28

+1 on checking for vacuum leaks, try the pipe on the rear of the inlet that goes to the brake servo, Got a slight leak on mine where it meets the servo seems to open up when the cars been running for a while im guessing the heat from the engine opens up the leak more

16th April 2012, 18:34

Ok, obviously a common issue, so I thought I'd better post my eventual solution to add it to all the possible cures for random revving.

My VTR had got so bad at reving itself as to be virtually undrivable in town, but only when warm. After changing the ICV, MAP sensor, temp sender and throttle position sensor, all to no effect, I seem to have cured it by changing the top lambdha sensor (£26).

I didn't honestly think it would do it as everyone say's a faulty lambdha leads to rough running, but mine wasn't actually doing that, and no fault codes were showing up. It was however probably the original, and at 113K miles most advice seems to agree it would normally be past its best

It's run fine now for a month and several 100 miles, so I'm starting to believe it's actually cured.

16th April 2012, 18:59

Quote:

Originally Posted by iannay

Ok, obviously a common issue, so I thought I'd better post my eventual solution to add it to all the possible cures for random revving.

My VTR had got so bad at reving itself as to be virtually undrivable in town, but only when warm. After changing the ICV, MAP sensor, temp sender and throttle position sensor, all to no effect, I seem to have cured it by changing the top lambdha sensor (£26).

I didn't honestly think it would do it as everyone say's a faulty lambdha leads to rough running, but mine wasn't actually doing that, and no fault codes were showing up. It was however probably the original, and at 113K miles most advice seems to agree it would normally be past its best

It's run fine now for a month and several 100 miles, so I'm starting to believe it's actually cured.

mines does this, although not as bad now, and it is the lambda that caused it, i replaced my whole throttle body and sensors and it still went mad.

18th April 2012, 21:27

ICV fixed my problem when mine did this like, i must have been a lucky one!

18th April 2012, 22:02

Check ecu plug or plugs. Make sure there nice and clean, also could be lambda sensor