[jpregione]

Hello,
I have a 2009 E90 328i, steptronics transmission, N51 engine with AA headers, cat back exhaust and AA tune with 60k miles on it, 99.9% of the time car runs great but on occasion (maybe once a month) when going slow the transmission will slip (engine idle increase but no speed increase) or just wont upshift. These symptoms never happen together and usually I take my foot off the accelerator and "try again", might take a few attempts but symptoms go away and all is fine.

I've never experienced a warning light however today my son told me it felt like the transmission was slipping (again at low speed) and the light came on so he pulled over, turned off car and when he turned it back on the light was gone and all was fine. I'm almost certain he experienced the same thing I do on occasion except I usually back off when I feel an issue and I can't say whether he did or not.

I am curious if anyone has experience with these symptoms and what the possible causes are. Again, I might have an issue and all is fine for a month and it will happen again, so far (knock on wood) the symptoms don't last.

Any help / thoughts would be appreciated.