I've had an issue with my 2013 l99 for a while now and haven't been able to figure it out..
What happens:- the car will feel as though the brakes are being touched for a split second the car will feel as though it's freewheeling, then the engine speed will catch up to the transmission speed really quick and the entire vehicle jerks... all this happens in less than a half second. Some times are more severe than others.
It usually happens within 30 seconds of a wide open throttle pull. It doesn't usually happen during the WOT pull, and it can happen even if I don't go into WOT.
The severity of the "jerk" seems loosely related to how hard I get on it at WOT.
This happened even when stock. The car is now boosted and has new injectors, fuel pump and I've changed plugs and wires twice. (Did help a little).
Using hp tuners, I see that the "blip" does reduce engine rpm momentarily by around 200rpm, dynamic airflow numbers spike high, fuel pressure drops (I believe this is normal for the e38), mass airflow numbers don't change (car is speed density tuned and doesn't use the maf), the wide band will read rich directly after the event.. injector duty cycle will also increase during the event..
Reply With Quote