E.O.D.

Not my vette but a friends. He just got off the phone with me and has been plagued with this thing for about a week now. Its an 02 coupe. During open loop it surges and bucks, but runs fine at closed loop.
He bought it used, it has a K&N filter as the only mod he knows of.

He's not sure if its been aftermarket tuned or not.


Any ideas or recommendations? I did a search on the other forum, and all I found in C5 tech was threads on closed loop problems.

Think it could have a custom tune thats either crap in open loop, or was tuned for FI? Or something screwy like that?

Maybe just a reflash to stock as a starting point?

Vacuum leak?

Any help is greatly appreciated. I have not put eye's on the car yet, but probably will tomorrow.

Thanks in advance.