[stevenh44]

Having some slight issues with my transmission as of late.

Info:
-09 328xi
-83,000 miles
-tranny fluid/filter/gasket replaced at 65k
-auto w/gm version
-check fault and shadow codes bi-weekly, nothing to report.

Issues:
1. Happens almost daily. Sitting at a stop light and I feel a bump or nudge of the car. Like someone tapped the rear of my car. But no car behind me. This is main issue, increasingly happening more often
2. Occasional hard down shift when slowing down to a stop. Not a surge like I've read from other complaints. Just a noisy hard downshift, and can feel it.

Other than these two issues, shifts and runs pretty good. When I press the gas more and let it hit upper rpm's, extremely smooth shifts. It's the cruising around, is when the issues happen.

Anyone experience this with their ride? Suggest changing the tranny fluids again? When I did the original fluid change, fluid looked great with very minimal clutch material on the magnet and bottom of the pan. I also did the differentials and transfer case at the same time. Differentials fluid looked and smelled great but the transfer case fluid was little warn.

[STR8-6IX]

Originally Posted by stevenh44

Having some slight issues with my transmission as of late.

Info:
-09 328xi
-83,000 miles
-tranny fluid/filter/gasket replaced at 65k
-auto w/gm version
-check fault and shadow codes bi-weekly, nothing to report.

Issues:
1. Happens almost daily. Sitting at a stop light and I feel a bump or nudge of the car. Like someone tapped the rear of my car. But no car behind me. This is main issue, increasingly happening more often
2. Occasional hard down shift when slowing down to a stop. Not a surge like I've read from other complaints. Just a noisy hard downshift, and can feel it.

Other than these two issues, shifts and runs pretty good. When I press the gas more and let it hit upper rpm's, extremely smooth shifts. It's the cruising around, is when the issues happen.

Anyone experience this with their ride? Suggest changing the tranny fluids again? When I did the original fluid change, fluid looked great with very minimal clutch material on the magnet and bottom of the pan. I also did the differentials and transfer case at the same time. Differentials fluid looked and smelled great but the transfer case fluid was little warn.

changing your fluid again isnt going to change anything if its clean, especially since you mentioned it looked fine when you changed it. the intervals for the GM box is every 100k anyways, so thats not the problem.

the GM box is known to have some low RPM driveability issues. the only thing you can really try is to reset the transmission adaptations.

on a side note, an ECU tune removes the low RPM "lag" common with BMW autos and may also help.

[patents]

Originally Posted by BimmerGeeks

It sounds like the NIC(Neutral Idle Control) to me. Search Bmw NIC issues & read up. It can be coded out.

x2

It puts the car into neutral when stopped to reduce emissions until the car is warmed up. I feel the bump. Once the car is warmed up, it doesn't activate. Pay attention to that and see if it goes away when the car is warm.

[tlow98]

Originally Posted by BimmerGeeks

NIC should switch to neutral regardless of engine temp. It's purpose is actually to save fuel by switch into neutral.

Only with the N51 right?

OP, is your car an N51 or N52 motor?

[stevenh44]

It's the N51 motor. sulev

[patents]

Originally Posted by BimmerGeeks

NIC should switch to neutral regardless of engine temp. It's purpose is actually to save fuel by switch into neutral.

I found this which suggests it's only during warm-up, although it doesn't explicitly apply to E90 N51 or N52: BMW-SI-B24-03-08

Note that it is not active in sport mode. OP can try sport mode and see if that makes a difference.

I have an N51 and can feel it, but I don't pay any attention to it. I'll pay closer attention and see if I can tell a change once it's warmed up.

[cybermgm23]

i had the same problem several months ago. took it to bmw and they did 2 things. 1) upgraded software to disable NIC and 2) reset ALL adaptations. Shifts and pulls like a new car.