Last night when i went to start my car it was really slow. I finally got it started and just assumed it was the battery. My dad took at look at it and listened to it when i tried to start it and he also said the battery. This morning when i took it in to get the battery changed their machine was broken, so we just had them replace the battery anyways. Heres the weird part, now my car is idling about 500 rpms and if i don't rev it every so often it sounds like it is about to stall out. I drive an 03 OZ Rally, any ideas as to what could be wrong? Let me know if you need more info!

 

500 isn't too bad... 600-700 is the norm. Probably it's the re-learning process and it'll take some time to re-learn it's normal operations. If you're not sure about what this is, search tab...

 

Wow, the exact thing happened to me yesterday. wouldnt start, sounded like a bad battery, so I replaced it, now it starts fine and everytime it idles, it stalls, like at red lights. I thought it was just a relearning thing, but i drove it around for like thirty min, still stalled, then reset it again and drove it for another 10 min and its still stalling! I am about to take it to Discount auto parts so they can check it with their diagnostics, ill post when i get back. only thing i can think of is that it screwed up the computer or shorted it out when i replaced the battery.

 

Apparently we didnt reset the ECU properly...
So, heres the fix-
1. disconnect the negative battery terminal and leave it off for about 15 minutes
2. reconnect and start up the engine. it should rev up pretty high then go into idle
3. let it sit there without revving it for about 15 minutes. for me it started to idle at around 1100 RPM, then it slowly crept down to about 700. i left the A/C off the whole time, but i dont think that matters.
4. drive it around for a little while, maybe 5 or 10 minutes to make sure its not stalling anymore. by the way, the ECU is resetting itself, so if you are excited about it not stalling and you race it around, its gonna make your car run rich (at least thats what others say) so if you want better gas mileage, drive it slow for a while
5. reset your clock and radio stations and your done!