Stuttering motor

[Tallsomeone]

2006 M Roadster.

Running steady at 5000 rpm in third gear, back off throttle JUST enough to have the very slightest first bit of engine-brake backpressure. Revs slow to 4.5K or 4K, then the motor and CAR jerk and release, jerk and release about twice per second.

It is NOT a physical bounce loop between my foot on the gas and the car's motion -- it is just the motor, hunting for "off" and "on" the throttle.

Anyone have this before? I imagine it would do it in other gears ...

I'm concerned.

Jonny

[BMW_RoadWarrior]

i was told it happens with EVERY BMW. i just sit and rev it at about 2k for a few minutes. the car seems to struggle if i drive it right away.

I've experienced that "hesitating" effect too. i don't think its a serious problem or even anything that could be fixed. its never happened if I've been racing..only if I'm cruising along, drop a gear and floor it if it hasn't been running long but, if it worries you..take it in.

[Tallsomeone]

The dealer's mechanic has an M Coupe, and he rode me in it and duplicated what I describe. He was surprised, because the stutter happened in his car, too! We think it is a very little spot in the revs where the variable valve timing shifts.

One has to decelerate with the engine being given just enough throttle to not "engine brake" the car to any firm degree -- which happens for me quite a bit if I'm running behind a car that is slower and want maximum return to power when the chance arrives.

Not a common situation, but odd to put up with.

My car does not do what yours does in the other situation.

Thanks for taking the time to reply, friend.