Firstfives.org

Engine cold starts and runs well, however, after it reaches normal temperature it will stumble and almost die (100-200 rpm) when I clutch and revs come down from 2000+ rpm. I can bump the throttle and it will idle smoothly at 1000 rpm. Seems to be worse when air temperature is hot. I replaced the throttle idle switch - no change. This condition is not constant, 50% of time it will go to idle and hold at 1000 rpm. I reviewed the FAQs on Throttle body adjustments and L-jet fuel injection and all seem to be in specs. Any input is appreciated.

Assuming you are asking about an Ljet big six, 528i, etc. From many previous posts (which you can Google search on the home page resources list) a smooth and lovely idle isn't easy to get. Tuning is a daisy chain of things that all have to be right, but perhaps you know that.

Having chased the problem myself, I've not found one single part or thing to say, " A Ha !" and that's it. Coolant sensor, fuel pressure regulator, dirty injectors, fuel filter, timed wrong, aux air valve sticking, air fuel meter old and worn, vacuum leak, bad grounds, idle switch set wrong, on and on.

If you're into it you can read the FAQ's, do the tune up check list and make everything wonderful(er) until the process improves the idle.

Or maybe a Guru will post the, " A ha," thing I've not found.

Thanks for the feedback, I'll keep working on it.

Problem solved,,,turned out to be incorrect wiring between WOT and idle switches.

WHAT?? Please explain your 'incorrect wiring' theory.

Wild guess, the wires were reversed ? I.e., wide open throttle switch wires were on the idle switch.

Interesting enough to try it to see what happens. Only because not connecting the wires to the idle switch on my (trailer hitching) '81 528i either doesn't matter much or might seem to be better.

Thus, the idle switch with or without wires doesn't seem to go crazy either way. But according to the post, it cares very much if the wide open throttle switch wires are on it.