Disconnected negative cable on my C4S yesterday, just to see if I could smooth out some rough idling I had been experiencing lately. I reconnected about 5 hours later.
Drove it pretty aggressively this morning to work.

The Good

• Idling is smooth as a kitten's purr, RPM does not fluctuate much at idle.
• Shifts are way smoother (with the PDK) than they were before
• The radio / XM presets don't reset themselves
• Feels about the way it did when I bought it

The Bad

• I forgot to roll the windows down before I disconnected, then you cannot safely open the doors (because normally the window adjusts itself when you open/close the door). Minor issue
• When I started up, a few things failed to initialize, namely PASM and PSM and something called drive-off assist

For the things that didn't initialize, I just turned off the car and restarted. Everything then worked except the drive-off assist. I'm hoping it'll just fix itself, plus I don't know what that is. Anybody have any experience with this? Nothing came up in search

 

That's alot of views and no responses. I take it nobody knows what "drive-off assist" is? Maybe an 09 thing? Specific to PDK perhaps? I'm gonna drive home in a couple of hours and hopefully it'll be all fixed whatever it is. Otherwise off to the dealer!

 

Drive off assist is the "new" function for the 6 speed which stops you from rolling backwards when starting on an incline.

 

Ahh, ok, so it sounds like they use that for PDK also as that is what I have. Thanks I am hoping it fixes itself, although I didn't notice any changes in the car rolling or anything with my foot off the brake.

 

When you disconnect the battery you will get the PSM and PASM warnings. You need to drive about a mile for them to reset themselves correctly after reconnecting the battery. Never heard of your drive off issue...

Jason

 

I drove home from work and all was good, no more warnings or errors. Thanks fellas