New cabby

[98mpart]

I have just bought a mk1 cabby, wrong time of year i know. It has a weird idle problem, when its started idle is lurvly @ 950rpm but after going for a drive and running to temp the idle sits proper high at like 1500rpm and doesn't drop back. Any ideas ?

[rubjonny]

what year/engine

[Neaty]

Sounds like a carb model with a sticky automatic choke on those lovely pierburg carbs

[rubjonny]

I'd say its more likly to be the waxstat if its a carby!  if it was autochoke it would generally run like arse from cold

[Neaty]

I'd say its more likly to be the waxstat if its a carby!  if it was autochoke it would generally run like arse from cold

mine never used to on my Scirocco, was fine until it was warm then it would idle at about 2k. But who am I to contest!

[rubjonny]

mine was the opposite, ran like an absolute dog till it warmed up as choke stuck on so overfueled, then idled at 2k for a long time.  If the engine was runnign for long enough it would run perfect as engine heat eventually disengaged the choke & stat.

[98mpart]

Tis a 1990 1.8 8V kjet

so not a carb issue, cheers tho.

[Neaty]

Tis a 1990 1.8 8V kjet

so not a carb issue, cheers tho.

Have you tried disconnecting the 5th injector? My mate had a similar problem on his Mk1 and took that off.

[kraM]

Hi

It sounds like the air by-pass thingy is sticking open, or has become disconected.  It sits behind the inlet manifold, has a 2 wire plu on it and has a pipe in and out of it.
It works by letting the air through it form cold (a bit like having your foot slightly on the throttle), and as it gets a voltage through it, the bi-metalic strip in it moves, covering the hole and lowering the revs.

If it is connected, try blocking the pipe, use a pair of molegrips to crush the RUBBER part of the pipe closed and see from there. 

If that doesn't fix it, let me know and I'll come up with another cunning plan...

kraM