Hi guys,

Ive got a 2010 automatic S. As I described the car jerks, hesitates, stutters when shifting. This is really only an issue when accelerating and decelerating up to 2000 rpms. Once the RPMs reach 2000 and are constant I don't feel much jerk....I feel the jerk behind the drivers gas peddle. I just replaced an intake boot that was leaking (however no code was present?). I have not smoke tested again to confirm all leaks are gone. I have oil? (green fluid) on my transmission bell housing which some people say is from a leaking vacuum pump, more specifically the O-ring? Wondering if this is a vacuum issue causing the automatic trannny to get out of whack.

I have a mini/bmw scanner and the only fault i read from the transmission is EGS switch steptronic not working.
I have had my timing chain assembly replaced already. Car is at 55k
Wheel speed senors all read correctly.

thanks Bob

 

Fix the leaking vacuum pump and be sure the transmission has the right amount of fluid in it.

Road test the car and see if the symptoms are gone or still present.

 

+1 on above advice. Vacuum pump is very easy to change, and you can get one for around $100. Good preventive maintenance at your mileage, regardless of need.

Also, search the forums on changing auto tranny fluid. You will see how to check level. I would agree that it sounds like it's low to me. I dropped the pan & changed my filter at 65k. I found it a tedious process, but not too technically challenging.You might want to consider tackling that, too.

 

green fluid is coolant. Your thermostat housing could be leaking.

The steptronic switch is part of the shifter assembly. when you put it in D and then push it to the side, that activates the steptronic mode.

+1 on ATF flush.

 

Already replaced thermostat housing? Any other common leak points?

Is the Steptronic Selector Switch the same thing as the transmission position switch? I would think they would rely on the same switch to adjust the gearing in normal and paddle shifting mode? I am getting a fault on the STEPTORONIC Switch and think they maybe related?

https://www.ecstuning.com/b-genuine-...h/24157551089/

 

 

Same switch for the gen 1 Cooper S Auto and the gen 2.

Possible the switch has a bad internal contact. Only another thing is the shifter itself. 25167550008

https://www.ecstuning.com/b-genuine-...c/25167550008/

Easier to replace the switch first.