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Solidev Solidev is offline
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Posts: 1
Join Date: Sep 2018
Car: 440i
Default Lag Between Shifts? - 09-16-2018, 09:37 PM

Recently installed a JB4 on my 2017 440i 8AT and I'm noticing a long lag between shifts...
When accelerating at full throttle, the car pulls very strong but completely falls on its face when changing gears.
This goes away when I change back to Map 0 - shifts are lightning fast again.

I've seen this same issue described in several cases. Some seem to be able to correct it with firmware updates, but even after updating firmware the issue remains for me.

  • Firmware: BMW_B48_B58_OBDII_9_T4.hex
  • 93 octane fuel.
  • Issue exists on Map 1 and Map 3 (only ones I've tried).
  • Car is otherwise stock.
  • Traction control and DSC are off.

Very disappointed. Any suggestions??

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Payam @ BMS's Avatar
Payam @ BMS Payam @ BMS is offline
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Join Date: Oct 2013
Car: e90 335i
Default 09-17-2018, 05:27 AM

Post logs on map 0 and map 1.

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RMM RMM is offline
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Join Date: Apr 2017
Car: 120i
Default 09-22-2018, 11:14 PM

post log, I think there is some programming in transmission and ECU, it seems to have map of torque vs shift speed where the higher the torque the slower it shifts

shifts are faster if you get your ECU flashed, or if you use sport+ form my experience, so it seems that there is communication between ECU and TCU, that both can effect shift speed
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