Very high idle 2.5k

[huggys-customs 0]

I've just put my engine back in and started it up for the first time after removing it 4 yrs ago to paint the engine bay and plate some parts.

 

When cold I start the car and it idles around 2.5k. I can close of the air volume screw and get it to drop to just over 2k. When I blip the throttle it often drops to around 1100rpm and stumbles and stalls unless I keep blipping the throttle. Then most of the time builds back up to over 2k.

 

I've checked the timing and set the idle screw and tps as per the haynes manual. 

 

I've checked for air leaks with wd40 and if I put my hand over the airflow meter intake it stalls v quickly.

 

Strangely if I unplug the airflow meter it idles at around 1k although seems v rich and lumpy. Then back to over 2k the moment I plug it back in.

 

I've tried winding the mixture screw all the way in and out by 7 turns as stated somewhere.

 

I've tried sucking on the vacuum advance line and that doesn't seem to let any air past.

 

If I unplug the blue coolant sensor the revs drop around 100rpm. 

 

This is all mostly when cold as I'm trying to fix it in the evening and not run it for hours and pee off the neighbours. But I've run it for around 10mins at a time while trying to see what affect things have.

 

I know this has been gone over before, but I've got an mot booked for Tuesday and I'm struggling to sort this out beforehand. 

 

Any help would be greatly appreciated. 

 

[huggys-customs 0]

Sorry it's a 1986 1.6 gti 

[DamirGTI 342]

There's one more screw on the TB , small one with metal clip , it is for the throttle butterfly adjustment .

Try to loosen (out/up) that screw few turns with the engine running at idle and see what happens .

 

Loosen TPS screws too .. as they can also put tension on the TB butterfly shaft .

 

Throttle cable also , slacken off if too tight .

 

Check if you have 12v (or near battery voltage) on the SAD heater 2pin connector .

 

If no voltage , SAD will stay open post warm up period . 

 

Or you've missed some vacuum leaks , entire SAD pipework is common for vacuum leaks especially hose on the bottom of the inlet manifold (kinda hidden) 

 

D

[Tom Fenton 1,542]

Put the bolt in the hole where the oil filler tower attaches to the side of the inlet manifold. Its a through hole and so makes a big air leak if its not there, but you wouldn't expect it to be a through hole. Seen it many times and its caught out lots of people.

[huggys-customs 0]

Thanks chaps. These are all things I've tried, but I'm going to go over things from scratch again, especially setting the idle screw and tps. I must have missed something. 

I'll keep you posted.

[huggys-customs 0]

OK so after a lot of double checking over the weekend, I realised I'd somehow missed that tps was holding the butterfly open when i was adjusting the idle screw down. I could have sworn I'd checked that!

 

It's idling fine and went through the mot today, the guy at the garage was great and tweaked it a bit more.

 

It's still not running cleanly under load, but I'll replace a few old components and see if I can get it sorted.

 

Thanks for all the tips. Really helped.