... you press down the clutch, release the clutch and the car cones back to normal!

Anyone any ideas?

RD

 

Do a search for "idle" and you will find millions of pages of info.

Does it do it sat at lights etc, when in neutral?

Depending on what year of car, its probably Marrion MAF sensor or Larry Lambda sensor

MB

 

Sounds like a MAF sensor issue (if you have a MY99/00 car)

 

Could be either Andy

MB

 

It only happens now and again, but the Neutral postion switch is knacked and the up-pipe sensors goosed, take that may be the problem then!


Thanks guys

Ricey

 

You mean the throttle pos sensor??

The sensor you mention is in "up-pipe" is actually in the downpipe, and controls fuelling off boost. If its dead, it won't idle right and will try to stall.

MB

 

DBM, I'm sure I have run my car without Lambda sensor connected, and it ran fine. Can't remember the reason for doing so, other than someone with me more technical knowledge than me (not hard) suggested it!

Should also add, don't mean that to be argumentative in any way

 

You can run without it, but its not advised long term - will run rich so your fuel economy will suffer. Long term issues are bore wash etc...

Failed lambda's tend to give a low reading, henc the ECU call for extra fuelling to richen it up. They often confuse the ECU and cause an erratic idle, as it cant determine an AFR reading.

MB

 

okely dokely.

Think the reason I ran with it disconnected may have been to try to fault find a problematic idle (MAF seemed to be showing correct readings, so disconnect lambda to see if idle problems got better, they didn't, replaced MAF< all was fine)

 

Yep, that is one of the tests. Again, its ok short term to do that - but best avoided.

MB