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Ke93 Ke93 is offline
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Posts: 27
Join Date: May 2019
Car: 335xi
Default 05-22-2019, 07:47 PM

Originally Posted by Русский шпион
Hi guys.
I have Z4 sdrive35is DCT transmission with JB4.
When I go WOT on speed about 60 miles/hr the car shifts back to 4th, sometimes 3rd gear and when it just starts to pull ( the gears are fully engaged already), suddenly a boost swings occurs , one or two waves 10-18 PSI, car stalls for the moment, then pulls normally with 16 PSI of boost, and upshifts without a problem.
It happens in all JB4 maps, except map 0 (OEM map 8 PSI boost max).
It happens with all driving settings , like sport and sport + with traction off...or just traction off..
It happens when I downshift it manually and then slam my accelerator...
It does not happen if I accelerate, but do not go WOT.
It does not happen when I go WOT on a 1 gear and car does not have to downshift.
So question is... what is it and how it can be fixed?
Custom tune of JB4?
If it is a "traction control" intervention how can I turn it off completely?
Maybe it needs a transmission reprogrammation/tuning to help it handle more powerful engine by not shifting down to 3rd gear from 7th?

to my knowledge this is caused by a button on the bottom of your pedal that puts your car in an optimal gear for performance mode. id imagine this setting can be tweaked like the jb4 has the ability to disable this function.
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