low idle '91 325i

ok i've been told this question has been asked before and is therefore common on this car, but i searched the forums and couldn't find anything. so here it goes; when i rev the engine while im not in gear, it normally revs, but it doesnt go back to idle properly; the idle goes really low then goes back to normal. and while the idle goes low all the lights dim. (taillights, headlights, inside lights) what can i do to fix this? thanks for any feedback.

the lights dimming is normal, low engine speed causes the alternator to not produce enough voltage to keep them lit properly (totally normal). and my car does the same. i just figured that the computer retards the timing so the engine returns to idle faster and the ICU takes over. causing that really low idle. but for me it only lasts about a second, so its really quick and it doesnt affect anything too badly.

oh ok thanks. i'm a new e30 owner so im kind of lost in some things. thanks a lot.

yeah i know how you feel, i got mine and i had to replace the head gasket, but i learned alot in that 8 hours.

lol i guess i have a long way to go

my car idles really really low when its cold(30*) and i shift it into gear. the rpms drop to about 200 and then the gear shifts and its all the good.I'm not worried about it because it only does it in the morning when im leaving for school

Originally Posted by esheg4ever23

ok i've been told this question has been asked before and is therefore common on this car, but i searched the forums and couldn't find anything. so here it goes; when i rev the engine while im not in gear, it normally revs, but it doesnt go back to idle properly; the idle goes really low then goes back to normal. and while the idle goes low all the lights dim. (taillights, headlights, inside lights) what can i do to fix this? thanks for any feedback.

I would check for vaccum leaks. These usually occur on the plastic elbow that connects to the throttle body. You shouldnt be getting that low, your computer is having to compensate.