slight surging when accelerating hard?

[Tee5alive]

The car is running smoothly now apart from the annoying servicing lights but im having them switched off!

On the way home from night shift gave it the beanz, away from the lights to put a cocky young M3 driver in his place and noticed slight surging but the turbo IS boosting as shes pulling away like an F16!

Very slight drops in power then back up did this a few times. On normal slow accel. nothing felt??

Ideas??

[Dream3r]

what fuel you runnin mate? is it mapped?

[Tee5alive]

what fuel you runnin mate? is it mapped?

bog standard cheapy stuff? Its not mapped YET no. So is it the crap petrol?

[Sweep]

My 850 runs noticeably worse with the cheap stuff in it, I always run on V Power.

[kyboy]

I'm the same run it on super market regular stuff and it does act up,run it on v power runs a dream!

[LeeT5]

An air leak can cause surging because it's unmetered air post MAF. so the ETM and ECM try to compensate, so you feel it surging.
Mine did this for months and was felt more when using the cruise control.
Fixed the air leak and all was good.

[Tee5alive]

An air leak can cause surging because it's unmetered air post MAF. so the ETM and ECM try to compensate, so you feel it surging.
Mine did this for months and was felt more when using the cruise control.
Fixed the air leak and all was good.

Thanks mate had a tweek of the clamps and put EXPENSIVE petrol in and she NEARLY fine but still a tiny surge. But now ALL fault codes have mysteriously cleared AND my cruise control started to work??