Idle Problems

rkeel0 · Aug 25, 2009, 08:36 PM

Hey first time posting here, and only moderatly knowlegable with cars, so please bare with me. I have a 2002 lancer es with 87k miles, automatic, with no mods, everything is stock, and here is my situation..

So today I installed an after-market stereo, and had no problems what so ever with that. I disconnected the negative cable from the batter, installed the stereo, connected everything and then reconnected the battery. Everything worked fine. However, I then took my car out for a drive, and noticed that now when i am sitting at a light, my car idles below the 1k rpm. tpically its around 800 rpm and periodicaly drops to about 400 rpm and shakes pretty bad. I know on previous cars i have had i just adjust the idler arm and its fine, but looking at it on my lancer, it seems its a colt i would have to tighten from what i can tell. is this what i should be doing? or is it possible something else happened? only thing i can think of is if the computer controls the idling rpm and it somehow got reset. Oh, and also, since doing this, the rpm's jump right before shifting into 3rd gear. they jump up to 6k rpm or so. any help or suggestions would be greatly appreciated.

Slad · Aug 25, 2009, 08:47 PM

how long was the negative cable from battery disconnected?

rkeel0 · Aug 25, 2009, 08:58 PM

no longer than a hour

Slad · Aug 25, 2009, 09:04 PM

more than likely what it is. Is that you reset your ECU and its relearning your driving style. it will idle funny/weird until it learns everything again.

Did you drive it right after your put the cable back on or did you let it idle?

rkeel0 · Aug 25, 2009, 09:09 PM

right after i connected it i drove,and hopped right on the highway to go into town, i noticed it doing that once i got off the highway and was waiting at some lights. and it continued each time i stopped. if i did reset that ecu, is there any to re reset it to how it was previously? (lol @ me?)

Slad · Aug 25, 2009, 09:18 PM

there isnt a way to re-reset the ECU. You just have to drive it until it goes through its OEM drive cycle.

However, i would suggest next time you disconnect your negative battery cable for about 30 min or more. Let it idle for about 15 min and then go for a drive for about 25 miles and try not to go over 3k rpms.

But no worries its just your ECU relearning. =)

rkeel0 · Aug 25, 2009, 09:20 PM

ok great well thats definately better news than i was expecting. Ill give it a week or so and hope that it gets back to normal. thanks for the help.