hello ppl i have a 4g15 dohc lancer its not a u.s lancer but maybe you guys can help me i am having areally strange everytime i take my battery out off my car and put it back in the engine does not idle smooth at all it starts off "rough idle " as though it has made an adjustment or a change to the "brain unit" then all i do is drive the car for lets say 1/2 mile or so and everything is back to normal it idles good again, this only happens when i take the battery out off the car and put it back in other wise my car works normal can any off u experts help to understand why that happens or what causes it and a solution ? thanks and sorry for this long post

 

The ECU may be reset every time you remove the battery from it's previous effert to adjust itself to allow your car to idle and run smoothly.
Why are you removing the battery so much??

btw this is only a theory but I think a pretty good one.

 

well unfortunately i had to remove the battery once to make to fix the holedr underneath that keep it in place and the other time was when i had to put the battery in my wife car because her battery died so i had to get it started, and yes i think that whats happening the ecu is ressetting itself but should it not have a backup battery in there? i only took it out for like 10min?
hope you can shed some more light but thanks anyway for ya help appreciated

 

The backup battery may be dead, or may not exist... If you're that concerned, call the dealer and ask.

 

i dont know about a backup battery, but when you reset the ECU by either removing the battery or just removing the connection to the batter, it does take the ECU a few minutes to recalibrate itself. dont worry bout it, as long as it runs fine after you reset it and it doesn't go back to idleing rough i'd say dont worry bout it.

 

I second what Smoktout said. This is not totally unusual.

 

Im going with what smoke out says. It is normal for the ECU to "learn" again. Same crap happened to my buddies cobra when he had a new header installed, the guy told him it would run rough until the ECU got "used" to the mod. After a little while of driving around the rough idle did go away.

 

GMs are famous for that too.... it is just the computer relearning idle parameters, some gms will die twice fefor they will even idle rough after reconecting the battery. If it bothers you that much just get one of those memory keep alive things that use a nine volt bat that plugs into the cigarette lighter before you disconect the battery