'Occasional' loping idle...

[VetteVet]

Schrade,

One other thought is an air leak in the exhaust. Negative pressure pulses can draw "false air" through an exhaust leak upstream of the O2 sensors and can cause the symptoms that you are describing. I would especially look in that direction if the loping that you are experiencing comes when coming down to idle after running the car at highway speeds (heat in the exhaust system opening up the leak).

Jep

[Schrade]

Originally Posted by VetteVet

Schrade,

One other thought is an air leak in the exhaust. Negative pressure pulses can draw "false air" through an exhaust leak upstream of the O2 sensors and can cause the symptoms that you are describing. I would especially look in that direction if the loping that you are experiencing comes when coming down to idle after running the car at highway speeds (heat in the exhaust system opening up the leak).

Jep

This one sounds pretty good too there Sir ...

The shop that did the tranny swap did have the exhaust down, and I do swear it sounds different (although I hadn't done that many miles on the car before). Doesn't SOUND too much like a leak, but will keep this is mind.

Will try to get a data log somewhere here as well.