MK2 Golf Gti idle erratic

[Dave Gibson]

My Mk 2 Golf (8v GTI, 1991, PB engine) has developed a problem "overnight", whereby the idle is erratic - at its worst the rev counter literally moves back and forward from about 1100 to 750 rpm - although when the car is hot is settles down a bit, but still running slightly fast and variable - if I tap the acc. pedal it will settle at varying rpms. At the same time an intermittent metallic vibration sound coming from the engine bay has developed, as if something is loose - I feel the two issues are related?
Can anyone tell me what the likely culprit might be and a reliable engine, or VW, specialist in Edinburgh that you could recommend. My usual, AutoWerke (gorgie) has just closed down.

Any suggestions appreciated.

Dave:confused:

[j_coupland]

Just noticed ur thread. Not sure about the GTIs at all but it could be that the engine computer (if it has one) has become corrupted. I went to Witherspoon VW in Sighthill Industrial Estate Edinburgh a few times with my Mk3 Golf, they are independent, pretty reasonable and they even clean ur car after the work is done! 0131 458 5444 is the number. Hope this helps!

[pmax]

Hi Dave

It sounds as if it is drawing air from a vacuum pipe. This would certainly cause the revs to be erratic at idle. Have a look at the pipes from the inlet manifold and around the air filter housing. Also check the air intake pipe from the exhaust manifold to the air filter housing, if this pipe is off it you will get a light metallic noise and could also explain the idling problem when cold.

[Dave Gibson]

Thanks to j coupland & Pmax for replies. Problem turned out to be coolant temp. sensor at front of engine (the blue one) so car telling ECU that engine was cold all the time, thus supplying far too much fuel. Running sweetly again. NB Problem traced by Bellingham Motors (VW &Volvo specialist) in Edinburgh City centre - would recommend. Dave :approve: