Mk1 Golf Gti idle woes :(

[ariser]

Hi Guys

Ive got a mk1 gti 1.6 cis system.

After replacing the auxiliary air valve and re-tuning the idle and co everything was alright for a few days and then idel has crept back up to 2000rpm.
I have checked the timing and the mark is exactly in the right place.
What could be causing this. All live feeds to wur,auxiary air valve and cold start injector are fine.
I Have cleaned out the injection system and there are no air leaks and am completely stumped as what is causing this.
The only thing I can think of is i have a 4 branch manifold that is not covered in heat wrap so could this be a heat problem or something?
Is it worth disconnecting the live feeds from the heater elements as the engine gets hot so quickly???

I use the car as a daily driver so really need to sort this out as Im fitting a fast raod cam soon.

Engine has only done 70k so still not even broken in properly as car was one family owned before little old me got hold of it hehe.

HELP  

[richandhazel]

Are you absolutely certain you have no air leaks? Check that Y shaped connector over the rocker cover.......there is a 'telescopic' arrangement there that can slide out and cause a vaccuum leak.........took me ages to find that when mine did it.

When you wind your idle screw all the way in, your engine should die as you are preventing any air getting past the throttle body, therefore if you're idle is still at 2k then air must be getting pulled in from somewhere.

[ariser]

Car does lower when screw is turned in. It just seems to increase in revs during a 3 day period. Then I have to retune it.

Another member in another forum suggested the o ring behind the screw might have perished so i am going to check that as soon as i can.

Cheers

[richandhazel]

Yep that 'o' ring can harden and become brittle......worth a look. Let us know how you get on........

[Gambit]

my 16v used to do this because of the O-ring on the idle screw

it wasn't a perfect fit and the idle screw could be turned by hand quite easily, which meant it would eventually unwind itself a few turns over a couple of days taking the idle up from 900 - 1300

in the end i forced another o-ring on also, and got it back into the hole with a bit of grease, you can now only turn it with a screwdriver and the the idle speed is constant at 950rpm ever since!

[rustynuts]

Mine did that when i bought it. Then again there was no idle screw in there, just a bit of stick!  

Anyway, I decided that the best plan of action would be to remove the old throttle body, and replace it with a Mk2 digifant spec one I had lieing around. Sorted the idle out no problems, just need to flow the inlet manifold to get the most out of i now!

[ariser]

This has got a nut on the end and not a screw nut i do not suppose it really makes a lot of difference.

Im actually looking for an audi thorttle body and inlet manifold with 16v regulator as ive heard this is a good mod to do an the mk1 and will compliment my cam when i put it in.

Perhaps I should wait for this to come up hehe ??

Cheers

[richandhazel]

Some have a hex head instead of the screw............7mm I think......one with the hex head is a lot easier to adjust than the screw.....facing and right up against that bulkhead  

[ariser]

The new screw has sorted the problem []

Now im back to my old problem of the car revs dropping after restarting the car after a short stop off.

I guess its cos my 4 branch manifold is not heat wrapped and the air valve heater is getting confused cos the engine is so damn hot still that it think that the car has been runnign and is not opening according. Arrrg.

Gonna order some heat wrap from proven products tommorow and get the car up on the ramp on the weekend and wrap the bugger up and see if that makes a difference.

Otherwise its back to seeing if I have a weird sort of air leak.

Ill let you all know how it turns out as soon as I do it.

Cheers