Bf Xr6Turbo Revs Surging Under Part Throttle.

[Sandman6]

Hi all, I just my car back after my second ZF catastrophe.

The car is surging under part throttle, by surging I mean the revs are rising and dropping a few hundred rpm as I accelerate off boost. Even with cruise control its quite pronounced. I have an engine light for an O2 sensor which I have replaced as well as the o2 loom to no avail.

I have sprayed Conyact cleaner through the plenum and reflashed the ecu and even rewored my throttle body.

The car has a new stage 2 BTA ZF box and heavy duty std lockup torque converter.

running a process west plenum,kit.

Please help, anybody had this issue?

also I might add that on full bost the car runs 100% but runs super rich when I let off. To the pointbwhere I can see the black fuel smoke while im at the lights

[Chaos310]

possibly dropped a cam chain guide and jumped a tooth on the crank sprocket... putting you out half a tooth at the cams...

check your cam timing...

let me know.

cheers

[Kosij]

Possibly a dodgy box from a dodgy workshop with a dodgy tune.

[TomT]

+1 with Kosij

Rev hunting is a possible symptom of ZF milkshake if you don't have an external trans cooler.

I'd check you coolant overflow tank for colour and substance