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      02-10-2017, 05:50 PM   #182
Private First Class

Drives: 2009 M3 E92; 2006 330i E90
Join Date: Jan 2012
Location: Arizona

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Originally Posted by smassey321 View Post
Zigsman, When you had the 2-1 bump, was it only when the transmission was hot? And when you did the solenoids, did you also do the valve body rebuild with a zipkit? I am getting the 2-1 bump but only when hot after having driven for over 20 minutes. I can easily duplicate the bump shifting from 2-1 manually while stopped.

The bump was always there but much worse after the transmission warmed up. I did not do a valve body rebuild, I only changed the solenoids. Based on my troubleshooting, I was confident I had a solenoid or two that were sticking which was what was causing the rough shifting. Basically, the solenoids are like the pistons in your engine, when power is applied, they smoothly move from one position to another (opened to closed or vice versa). This is what allows for the smooth shift. Picture the piston moving through a sticky or gummy gets bound up and then breaks free all of a sudden... That is what I believed was happening, which would cause the sudden and abrupt shift. So, I replaced all the solenoids (no knowing which one controlled the shifting from 1-2) and, the problem has been fixed ever since.