MHD - Boost Limit by gear issue


New Member
Mar 26, 2020
Anyone running issues with Boost Limit By Gear on MHD? Currently, working with my tuner and we are finding that in 2nd gear my AT is not liking full boost of 26 psi (for obvious reasons) which ends up spitting out a 4F92 code via XHP, indicating clutch pack slippage at about 5K rpm. This slippage did not occur before and the trans were fully functioning prior to going 100% port meth and updating the tune.

We enabled the boost limit by gear at 11 psi, then 12 psi. This works as it peaks about 13 psi but tampers down to about 9 psi at redline, it works to mitigate the slippage issue completely but now it feels dead at the top of 2nd.
See log:

Next, we up the BLMPG limit to 14 psi to address the dead space at the top of 2nd, we found that the boost limit no longer works. I get full boost up to 24 psi again causing the trans to freak out at 5.6k rpm. See log:

I repeated this at 13 psi and same issue occurred so it seems like 12 psi is the limit I can set prior it going full boost in 2nd.

Has this been experienced by others? Any thoughts? I was able to track this same exact issue down on from a 2018 thread on another forum with no solution so it seems like this isn't a new issue. Would link it here but don't want to go against any policy.

Mods: PS2 + FBO + 100% PI Meth on a 335xi AT on XHP S3
AT fluid and seals will be replaced shortly to ensure the fluid wasn't burnt up during the several clutch slippage occurrence.