low revs on cold start -golf mk3 1.8

[noho]

hello, would really be grateful if any members could shed light on this. My trusty 1996 1.8 GL (80,000mls) recently started as per normal but then after a couple of mins approx revs would suddenly drop momentarily to around 500rpm before something told the engine to compensate and it would swing back up to around 1200rpm. This see-sawing would also continue in fairly regular pattern with momentary losses of power when driving. Took into reliable garage (not VW) who diagnosed faulty idle speed actuator and replaced. The original problem has now gone completely however now when it starts from cold it idles very low on the verge of stalling at around 450. It needs nursing with accelerator until it warms up when it purrs perfectly at around 900 RPM.
Slightly concerned that in fixing the main problem it has created another smaller one! Any thoughts as to what logic lies behind this chain of events MUCH appreciated. Thanks

[0llie]

hi i have EXACTLY the same problem and quess what.... i have a golf mk3 1.8 driver, haha,

one thing i have replaced was the rubber block under the mono-point injector, mine had crack so it was letting excess air in and letting petrol out!!

but the problem still persists, so i would love to find out what wrong too,

i had one guy say it could be the fuel / air regulator?? what ya think?

[noho]

hi i have EXACTLY the same problem and quess what.... i have a golf mk3 1.8 driver, haha,

one thing i have replaced was the rubber block under the mono-point injector, mine had crack so it was letting excess air in and letting petrol out!!

but the problem still persists, so i would love to find out what wrong too,

i had one guy say it could be the fuel / air regulator?? what ya think?

Ollie, when you say you have the same problem do you mean low revs at cold start ? This problem started immediately when the new idle speed actuator was fitted and solved the earlier more serious problem. No idea why.
I fitted a new temp sender yesterday, no luck. Maybe the choke needs stripping down cleaning etc. But i'm a curse on all engines i touch so it will have to wait for someone who knows what they are doing. I am determined to sort it as its a great car.

[0llie]

well i havent had anything done on my car i was just driving one day when i put it into neutral it just died!!

ok my friend we need to narrow it down,

i have changed the mono-point injector rubber --- NO LUCK

you have changed your Accurator - NO LUCK

changed temp sensor - NO LUCK

have you thought of putting you old accurator back in to see if the problem persists??

[noho]

well i havent had anything done on my car i was just driving one day when i put it into neutral it just died!!

ok my friend we need to narrow it down,

i have changed the mono-point injector rubber --- NO LUCK

you have changed your Accurator - NO LUCK

changed temp sensor - NO LUCK

have you thought of putting you old accurator back in to see if the problem persists??
Ok Ollie, the saga continues.....
I have now also changed rubber flange under throttle body which also had a crack in it - no luck
Temp sensor - no luck
Throttle body - no luck
Idle positioner - no luck
Lamda sensor - no luck

Well I say no luck but the cycling revs seems to have stiopped albeit temporarily and It now idles constantly at around 800 rpm BUT i still have to nurse when starting otherwise it will stall. I should have sold it ......but £600 later I'm going to solve it if its the last thing i do!!!
Calling all techys - how do i get the choke to kick in as it always did?????

[noho]

forgive me talking to myself here....but i have solved this niggling problem...which may be of use. The reason too much air was getting in causing the surging was that the pin in the idle control actuator needed re calibrating....remove unit, roll back rubber gaiter and turned pin by hand....simple! ...... VW were hopeless and blinded by obsession with fault codes......It took a good old fashioned mechanic to work it out thoughtfully by elimination....

[garymansell]

Hi, I have very similar symptoms with my mk3 GTi16v (ABF). I wonder if you can tell me how to find the idle control actuator as I can't find mention of such a thing on my vehicle - would it be the idle speed valve?

Rgds