View Full Version : 98 A4 New battery issues! Wont drive right

07-29-2009, 11:09 PM
So one of my friends, Koncluded, just put a new Optima battery in his car. Since then, his car has just not been running right. We have readapted the throttle body, cleared the CEL, drove around for a little, etc! The car has a hard time finding the idle spot, after a little it will sit perfect, but once you press the gas it fluctuates a lot as if the car is going to die. While driving, it occasionally dies when cruising without gas. Any ideas? Its just weird because his car was not like this at all and was in perfect running order prior to the battery change. Any help would be greatly appreciated.


07-30-2009, 12:24 AM
if i remember correctly 98 has a throttle cable and not a drive/fly by wire... so you cant adapt the throttle body... anyways, over time, crud will build up in the throttle body, and on the butterfly, so the ecu has to "adjust" to this. when you set the ecu by replacing the battery, it doesnt remember what setting it was at and uses a "basic setting"... now because its now at a basic setting mod, and has all that crud blocking the throttle body, i dont know where the hell im going with this anymore... lol...

clean the throttle body with throttle body cleaner, as much as you can outside of the butterfly, clean the butterfly, and as much inside as you can... put if back together and try it out... this happened to my girfriends 98 2.8. i disconnected the battery, then after the idle was low, it would die out, when i would come to a stop sign it would die out... girlfriends cousins works on audi/vw, and said something about a basic setting, then said to just clean the throttle body out. i did so, and it ran so much better. idle was on point, never died out, and just felt better in general... hope this helps...

07-30-2009, 01:35 AM
Have him turn the key on without starting the car. Listen for the whirring and little noises. Let it sit like that for a minute before starting the car. Then just let it idle until it hopefully stabilizes.

He may have gotten a bad battery. I had one a year ago. Optima had to crank up production for the war and they've had a few bad ones slip through.

07-30-2009, 08:02 AM
The battery was indeed an Optima! I believe he has tried to sit there with the key in ON for a couple of minutes, maybe even hours lol.

07-30-2009, 11:54 PM
hours was correct -_-'
not much improvement. Although I don't think it the battery is the problem. I'll probably go and try to clean out the throttle body and go from there

thanks a lot guys

07-31-2009, 07:46 PM
I had a problem with my 1999.5 after the battery went dead the engine didn't seem to know where to run it seemed to be searching for the right place to run the car was undrivable. After going to web sites like this and others I decided that the the throttle body had to be adapted I found scan tool on the internet called memoscan its a vw/audi can bus vag 5053 it can read and clear check engine light codes and it has several built in programs one of which will adapt throttle body values. After hooking up the scan tool and adapting the throttle body the car ran perfect and I thought I was a genus until the next problem came along. The web site for the tool is www.diydiagnostics.com I think it cost me $150 hopethis helps.

08-02-2009, 01:46 AM
so i ended up buying throttle body cleaner, and sprayed the shit out of the TB and wiped it down. It got cleaned, and after i turned the key to the on position to let the tb re-adjust. Then started it up and it and it was perfefct

note to self: never let throttle body get super dirty -_-'

thanks for all the help guys