problem: 16v doing stupid revving to 2500kish when it's supposed to be idling.

[monzablue16v]

Hi guys

Another one of the 16v problems has reared it's ugly head.

 For a while the revs have climbed to about 2000rpm when the engine warms up, normally I can't find the reason it does it and it's not the throttle cable sticking, don't think it's the throttle switch either as I have jumped out a few times when it starts doing it. I have also nipped the airbox to ISV pipe which normally makes the revs drop but not this one it just sits there revving away to itself and it's always at the worst times in the middle of town, traffic lights, roundabouts I always know when it will do it as the car runs away from me a bit as the revs climb up making the idle quicker which is fun when your braking in 2nd at 30mph to stop a rear ender.

It is seriously driving me insane apart from the mental fuel consumption I seem to be having ongoing problems with it idles and runs fine maybe a touch lumpy on idle but not a massive amount.
Today it started doing it just as I came round the corner to home and as I turned it off the rad fan was going I wonder if this has something to do with it ??
Any ideas from you lot??

[dubsport]

hey,

dunno if this will help at all but ...

I have a '90 1.6 Driver with poor auto choke cold start problems, took it to Clive Atthowe Tuning in Norwich. Got a full and comprehensive report, cost 76quid, apparently she suffers from common golf carb problems.

Reading from the report, try the replacing:

Waxstat – which on my dub is causing high idle speed (choke vacuum pull-off unit failed causing over choking and rich mixture/ miss fire from a cool engine.) Also was told that genuine replacements are hard to find and costs a few sheets  it's all worht it tho, huh? 

Rich

[rubjonny]

Rich1.6: Non of that is relavant to a 16v, but all those problems you have there sound like they're casued by the coolant channel o'ring in the inlet manifold, not the choke or waxstat.  (Which are operated by coolant flow from the o'ring, it degrades and eventually seals off coolant flow, causing the waxstat & choke to stop working)
Check my pierburg 2e2 FAQ, it explains it all

Monza: Have you gone thru the 16v tuneup guide in the maintenance section?

[Gambit]

it'll be either the throttle switch, if not that then the isv module

u can test the throttle switch by holding the throttle open over 2krpm, and then pressing switch closed with finger. if working the overrun valve will open and revs will drop momentarily then rise to + 2k again

if its annoying to drive - you can disconnect ISV & it will idle/drive normal  (just set idle to 1krpm when warm using idle screw). though it'll idle low & rough for about first 10mins from cold start just while it warms up

[monzablue16v]

Rub: Yeah she seems to be tuned correctly it's just every now and then and always at the wrong times.

Gambit: I will have to double check the throttle switch I'm sure it's fine but always worth checking again! I would disconnect the ISV but it only happens every now and then so it's bugging the life out of me and I would rather keep the ISV for the moment. Hmm might be time to throw it at the rolling road again see if he can get the tuning bang on then see if it still does it