unwanted acceleration in reverse gear

[pfitzingerr]

My 2011 328i convertible with auto transmission has an odd tendency to accelerate when shifted into reverse. This happens when the engine is cold, especially when the outdoor temperature is cold. It feels like someone has tapped the accelerator without the driver doing so. Usually occurs when backing out of a tight garage space - where you back a bit, then apply more pressure to the brakes. It is at this point that the engine seems to rev higher fighting against the braking. I have asked BMW service to evaluate at so far their only suggestion is to let the car warm completely before backing.

Appreciate thoughts.

[M62pwrdE38]

When the engine is cold, its going to idle higher to warm the engine up faster, so the idle wants to stay fast even when in gear. With how short reverse is geared, it is your most powerful gear at the lowest rpms. I would just back into whatever parking spot and not worry about it.

[cheech1]

If I'm understanding your description correctly, it sounds like your car has a problem. Since you are probably still under warranty, I'd have it checked out at your dealer.

[pizzaman09]

To me it sounds like your car is in warm up mode, hence it is idling high. On my e38, the warm up mode is very similar to the sport mode, where it holds on to gears longer to keep the revs higher.