EGT Pre-turbo ST


Sep 30, 2021
Northwest Indiana
2009 335i - xdrive 6MT
To start off, I recently finished my engine rebuild after a long 3 year hiatus, and along with the build came a single turbo kit from speedtech.

I am now in the process of tuning the car but seem to be running into some issues with EGT. According to logs we are getting up to 1742 limit and cutting boost until it cools down then surging almost when the DME feels its cool enough to boost again.

My biggest question is how does the DME actually calculate this? Are there tables that need to be modified to reflect accurate modeling when ST?

I decided I would drop the lean spool from 13.5 to 12 to see if that helps any (havent had a chance to get out there for some runs). I also had spool mode until 4200 RPM since the turbo is a little laggy. I am going to drop this to 3800 and work from there. However I never had this issue with twins and one would think with more resistance in the twins the EGT would be hotter. Any help would be greatly appreciated, wondering maybe if it has to do with O2 sensor location now Pre turbo?

Bad Log WIP tune