Unstable idle with cold start (GTX)

[the edmundator]

My GTX has started giving some trouble when starting from cold. The revs hunt up and down and invariably it stalls unless you keep giving it some throttle. Once warm , the idle is a bit unsteady, but not anywhere near as bad.

I am wondering if this sounds like a dodgy WUR, or is something else more likely?

[GTXTRA]

Scala suffering the same - improved with a replacement cold start thermo switch Ed.


Similar to this - http://www.ebay.ie/itm/VW-GOLF-JETTA-MK ... Sw7FRWYa0S

[the edmundator]

Is that definitely the right part you've linked to?

Part number 043906163A they've listed is still available new... For £105!

[GTXTRA]

yep,i got a couple of second hand ones from stevedismantlers on ebay.

[mark1gls]

Idle screw working it self lose, try adjusting the idle up and see if that makes any difference, the rubber o-ring gets brittle and flat and the car idle speed drops and the idle stability valve is the only thing keeping it running, new o-ring in pence compared to replacing the expensive bit's first?

[grandell79]

And also a good idea is to check the fuel pressure. Mine where sputtering and didnt idle well when cold. Then i checked the pressure. almost 0 when cold. Made the wur adjustable and raised the cold pressure to 1,5 bar. Then it starts just fine and the idle is stable.

[BlackGTX]

My gtx was exactly the same. Adjusted the idle and air fuel mix which made it better but it was swapping the warm up reg that cured it

[chopperoli]

If it starts up OK but then just idles rough, then its less likely to be the thermo switch, and more likely to be fuel pressure / leak / blockage related...

But rather than just guessing and wasting money on parts to swap, borrow a pressure gauge and multimeter to check things are in spec... btw I fixed a similar problem by cleaning out the aux. air valve, and a pressure test showed I needed to renew o-rings in the pressure regulator. You can get service kits for the WUR and metering head btw... you're a clever chap, save yourself some money!

This is a good chart to follow because it suggests the priorities of things to test in order:

[bensspares]

Check that the consatena rubber connections are not split.