juiceya6

Car was hesitating to start and then die. The first thing I did was jump the battery. After that the car started right up and ran with no problems. So! Go get a new battery. Back Ground
98 A6 with 90k miles. I am at a lost as to what to check next. Any suggestions would be greatly appreciated.

MP4.2+6.0

In disconnecting the battery, you did a reset (recalibration) on the engine computer (ECU) as well as the tranny computer. While it should default to pretty smooth running, it may be you have enough deterioration in engine components (timing, fuel or smog related) that the computer will have to "re learn" your engine's characteristics. You would likely see a check engine light though (is that working?), but it may take two cold to warm cycles for that to activate depending on the fault. You should VAG-COM scan it for error codes if you have access to the OBD II cable and software.

Also, make sure you didn't physically disturb something in changing the battery--a nearby vacuum line or electrical connector, for example the ones just in front of the front firewall. If so, again you would likely get a check engine light too.

im_cecil

See the link, and it's documented in the manual.<ul><li><a href="https://forums.audiworld.com/a6/msgs/407100.phtml">https://forums.audiworld.com/a6/msgs/407100.phtml</a</li></ul>