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      07-02-2019, 01:55 PM   #2768
techwhiz's Avatar

Drives: e90 335i Sedan - Arctic
Join Date: Feb 2012
Location: Bay Area, Ca

iTrader: (4)

Originally Posted by Soden82 View Post
Don't think it's related at all but I sold my buddy my N55 with the ZF6. I had the xhp flash on it when I owned it in conjunction with the JB4. Never had any issues.

He purchased the car from me with stock ECU flash no JB4 or MHD. We flashed the xhp tune and the car kept going into limp mode with coolant warnings on the dash. Stage 3 flash.

Flashed the car back to the stock trans flash and uninstalled xhp and the cars working fine now. Don't see how the TCU and ECU are related in any way but it's an odd coincidence.
You didn't state if you were running Stage 3 when you had the JB4.
JB4 allows water pump control so you can run it longer and higher speed.
Automatic cars have a transmission cooler, tied to the radiator.

There is correlation between the JB4 and coolant temperature and therefore transmission temp. Stage 3 can heat up the fluid depending on what you are doing.

You also don't state how many mies and the condition of the fluid.
I don't have issues with my n54 but I also have the sport package with an oil cooler and an extra capacity radiator.
Arctic Metallic\CF Splitters, Spoiler, Mirror Covers\LED Tails\LSD\Tinted\Coded\Apex Square SM10-19"\LED Angel Eyes\Gloss Black Grill\Integrated V1 & Galaxy Tab\M-Performance Brakes\Cobb Tuned\xHP Flash\Resonator Removed and -> is your friend.