My van is a 1985 1.9l petrol Digijet with an automatic gearbox. It was running OK until my local garage did some work to fix an oil leak, and now neither the garage nor I can get it to run properly! The garage will take another look, but not for several weeks (I'm based in Norway, where everything basically stops in July). Right now it's on my driveway and I'd like to figure it out myself, if possible.
It starts nicely - no hesitation - and will continue to run as long as I keep my foot on the accelerator, but as soon as I take my foot off the pedal it stalls immediately.
I initially thought I could just shorten the accelerator cable to give it more revs at idle, but if I do that the throttle position switch doesn't work properly. I have adjusted the switch so it closes with the throttle as open as possible, but it's not enough to prevent the engine from stalling.
Am I just being thick? Is there an easy way to increase the idle speed without shortening the cable (so the throttle switch still works)?
Things I have tried/checked:
- Adjusting the big screw on the throttle body. I think this should control the idle speed, but it doesn't seem to do much at all. For now, based on advice I've read online, I've screwed it right in then backed it off three full turns, which seems to be a common "default".
- Tested the throttle position switch with a multi-meter. This seems OK: closed at tickover and full throttle; open in-between
- Tested resistances at the air flow meter and the temp. sensor II. Both seem OK
- The idle control valve does not buzz/vibrate with the ignition at the first position, and it's hard to tell if it's vibrating while the engine is running, but it does vibrate after the engine has stalled. I think it's working correctly, but not certain. I have taken it off and given it a clean anyway.
- If I get someone to help me keep the revs up (so it keeps going), I can clearly notice a difference in engine note if I unplug any of the ICV, Temp. Sensor II or AFM. As the resistances are also roughly correct, I think these are probably working OK.
- I tried bypassing the idle stabilisation unit by unplugging it and joining the two connectors. Doesn't seem to make any difference.
- I've cleaned the contacts on the idle control unit (the little black box behind the lights). Not sure how to test this further, but no reason to suspect it (it was OK before).
- I tried spraying starter fluid around the air intake hoses to check for a vacuum leak, but didn't notice any change in engine note. If I disconnect the ICV and spray fluid directly into the air intake, the engine speed increases. Not surprising, I guess, but maybe indicates a fuel supply issue?
- I tried taking it for a "test drive", keeping the revs high enough to avoid stalling. The engine had very little power - I couldn't get above 40 km/h.
Running in neutral on the driveway, the engine sounds OK with just a few extra revs. This feels like it should be an easy fix, although the lack of power when driving makes me think it might be more than just idle adjustment.
What else should I be checking?
Thank you!
