wheel_of_steel

I have this problem where it's impossible to smoothly roll onto the throttle pedal. No matter how gently I whisper on the pedal, the engine gives a little jerk as it transitions from deceleration or cruising, to accelerating conditions. That isn't the only time, but it's the most obvious time. I thought it was just my driving, but nay I can drive other vehicles with limo smoothness.



Look at this video:







I hold the revs steady with the throttle at ~1300 rpm, and then ever so gently touch the gas. Notice how the revs briefly dip about ~100 rpm before increasing? This is what is causing the jerk.



Why does this happen? I have driven four different DOHC X3s and they all do this to some degree. It's more noticeable with wrecked engine mounts, but they are only a symptom of what seems to be an engine management problem.



Cheers all.

Stocker

Try lubricating the throttle cable?

wheel_of_steel

Already on that game. It's not the pedal that's the problem, I can feel the plate opening smoothly. The engine just has that little 'cough' before it starts to rev.

ScoupeLS

Check spark plugs and wire leads. That happened to my rd2 recently.

Tak82

or check the slack on the cable..if it's too loose, they need to be adjusted.

wheel_of_steel

Bump.

This problem is still messing with me.

It seems like the engine management lags about 0.2 seconds behind throttle inputs. Cracking the throttle when cruising/decelerating makes the engine 'cough' before catching on. When rolling off the throttle to change gears, you can feel the engine mildly bucking. TPS and plug leads/boots are all tested as good. I've tested all around for vacuum leaks.



What gives? The car is otherwise fine, she makes plenty of power and the fuel economy is utterly normal.

WytchDctr

Slow derpy maf?