idles up and down alot

[Haribo!]

i dont consider it broken but my new 16v gti idles funny, itll sort of pulse then sometimes drop rather low then limitedly jump up to stay alive then back to the pulse, it has a 4 branch manifold which makes a tinny noise(im assured that its fine tho),full stainless, 50mm inlet and a pipercorss induction box, would any of this do anything to the idle? it would just be nice if it sat still, still bloody fast tho!

[Mk2Kezza]

Mine is an 8v but had a similar problem to that. I think changing the blue temp sensor may help - get one from VW not GSf as apparently the Original ones last longer.

[VeeDubGTI16v]

give the isv a clean with carb cleaner and also do the end of the idle screw, usually helps when mine does that

[Dizzie]

if you want to loose the tiny noise off the 4 branch then wrap it in that exhaust wrap. haven't done it myself, but been told that cures it.

[jezza16v]

The exhaust manifold should not affect the ide at all, it should idle evenly somewhere between 950 and 1050 rpm. Most that I've set up seem to be a tad over 1000. Clean out the isv as said, and check all the vac pipes are sealed and also the pipe from the isv to the intake pipe. The joints are just push fit and they get worn and leak. Most end up with hose clips on them. There's also a very short tube from the overrun cut off valve to the bottom of the inlet pipe just behind the air box, this is a pretty poor fit at best and also gets worn and leaky. There is no 'blue' temp sender on the 16v although it has an equivalent. There are four senders on the gearbox end of the head, three are identical temp senders but serve different functions. If you want to check them, run the engine up to working temp and then switch off. Turn the ignition back on but don't start the car. Pull the connector off the one to the temp guage, I think its top rear, you will know because the temp guage will drop to zero. Then disconnect the other two and put the temp sender wire on each in turn, they should give you a similar reading on the temp guage if they are OK. Hope this is of some help 

[Gambit]

is this starting from cold? i get a similar problem because of overfuelling (my warm up regualtor has been modded) - i just disconnected the cold start valve

how low will the rev's drop? are we talking only a couple of hundred rpm? if so then sounds like the CO% is not set correctly which is cause it to hunt.

also, for reference on the temp senders on side of the head

red/yellow wire = temp guage
red/green wire = ISV
blue/white wire = ECU

[Brads MK2 GTI]

So Harry, how are you enjoying having a real car at last?

[Haribo!]

its great, i find myself insted of ragging around like i did in my driver just cruising the speed limit and soaking up all the pride of driving my gti,


as for the idle its just passed its MOT and the mixture and everything els they check is perfect, but once i learn more about this engine ill try the things you said, got a spare blue sender with it so ill change that for the sake of it

[Deefadog]

The 16V don't the blue temp sender!

Get some contact cleaner and clean up the ECU connection also! In fact clean all connector in the engine bay while your at it

[Judderi]

Does anybody know the part number for the temp sensors?