Hi all, I know this has been covered lots but can’t seem to get my idle sorted, the car was close to cutting out when I came to a stop then the idle would creep back up to 800 again.
today I took of the throttle body, took off the idle control valve and the sensor on the throttle body, cleaned the throttle body, and idle control valve really well, put it all back together and it’s worse than it was, tried resetting the idle but when I next start it, it’s bad again, and worse when it’s been driven, also I’ve noticed a vapour from the exhaust even when the engines hot, must be something I’ve done but don’t know what, any help would be appreciated
Have you looked up the thread on this (I think in engines/ “engine cutting out after battery change” or something…?)
I learnt a lot from that, including;
After working on the fuel tank filler, with batt disconnected, I had that problem (had had it before, though not too bad); Before looking into all sorts of component failures, try the following:
Take the car for a drive, get it hot, then park it in your driveway/safe place, & LEAVE the engine idling for 10-15mins…
This “appears” to get the ECU to memorise the correct idling speed, and FOR ME (!) it instantly cured the problem, which had become so bad the engine was stalling every time I dipped the clutch when stopping. Also seemed to be worse while the engine was still warming up, ie 5-8 miles after starting up. Didn’t really occur after I caned it a bit & got the engine nicely hot (not just on the water temp gauge…)
Good luck, always worth trying before changing/otherwise working, on various components. Let us know how you get on!
Argh, I’m having the same problem since changing my valve cover gasket yesterday. The battery was disconnected for a few hours whilst doing this. I’ll try leaving the car idling tomorrow to see it sorts itself out. I didn’t realise the MK2 ECU was capable of learning anything
I can’t think what else it could be as it was running perfectly before I changed the gasket, I’ve checked the PCV valve is working okay, all other connections look good, I didn’t touch anything else. I put half a bottle of Redex into a full tank of fuel aftewards so unless that has dislodged some crap. But then if that was the case surely it would be running rough all the time?
The engine runs sweetly in all conditions, except when I slow down to a halt and then it drops to ~500rpm for a couple of seconds. Yet while I’m pottering about reversing it into the garage, or parking at work it idles fine and doesn’t drop at all…
EDIT : to come to a conclusion on my problem, before I had a chance to try leaving it idling for 15 minutes, it fixed itself. To me it does appear like the ECU had got into a funny state after leaving the battery disconnected, as if by magic on the way home from work yesterday the idling problem completely disappeared.
