High idle issue 89 1.6 gti

[James85 0]

Hi folks, just wondered if anyone had any advice, couple of little issues I’m trying to get to the bottom of which may be related or not. Car is a 1989 205 1.6 gti. Runs around 1000 rpm when cold and goes between 1000-1400 rpm when warm, also Iv noticed when driving in the lower gears and higher rev range the car is sometimes a little jerky and “kangerooing “ had it to a mechanic , and had all the vacuum lines checked, the fuel mixture and timing etc, I. Changed quite a few of the ignition parts since owning it also, such as coil, leads spark plugs etc. thinking AFM next? Just wanted other opinions tho. Cheers

[stewal 8]

Jerking like that can be caused by the distributer vacuum advance not working.  The diaphragm often fails which can also sometimes allow extra air in on the inlet side to mess up the idle and mixture. 

[James85 0]

I’ll check that out, what I let side, does that not have a vacuum hose to the throttle body?

[stewal 8]

Not sure what you mean: the vacuum hose should run from the underside of the throttle body to the vacuum advance unit on the back of the distributer.

 

If the diaphragm is holed, or the hose is leaking or missing it will let unmetered air into the inlet manifold.

 

Try removing the hose from the distributer and sealing it with your finger and see if if alters the idle.

[James85 0]

Thanks mate, just replaced the hose somdeffo no cracks there, I’ll try holding the finger over it