Wastegate Oscillation issues

[Popematt02]

Hello everyone,

I’m having a very weird issue with my car, a 2015 m4. Car is 6MT, tuned on MHD Stage 2+(91 or E30 depending on what I fill up with). Only modifications are front-mount VRSF intakes, BMS charge pipes, and ARM downpipes(catless). Even stock, I noticed a slight oscillation in the acceleration but thought nothing of it. Since installing downpipes and going stage 2+, the oscillation is terrible at lower rpms. Timing is consistent and the only thing I can see is that my boost deviation is anywhere from 2-5 psi at WOT(I am at 4800 feet above sea level so this may be normal), and my wastegate duty cycle is erratic.

I’ve tore the car apart looking for boost leaks, I don’t think that’s what it is. What else could it be? No codes on the car. Attached is a segment of a log where you can see it very well, WGDC jumps from 35-100-35-100-35 very quickly and boost follows. Boost is dark blue, WGDC is light blue, and rpm is green.

Log was on stage 2+ 91. Thanks in advance!

[F80RN]

I’m not sure if I’m addressing your concerns, or answering from a different perspective. However here’s a thread I started last year regarding my personal Wastegate concerns


https://f80.bimmerpost.com/forums/sh....php?t=2020585

[Popematt02]

Originally Posted by F80RN

I’m not sure if I’m addressing your concerns, or answering from a different perspective. However here’s a thread I started last year regarding my personal Wastegate concerns


https://f80.bimmerpost.com/forums/sh....php?t=2020585

Thanks for the help! I ended up flashing to stage 2 instead of stage 2+ and the issue went away. I don’t know yet if it was because of adaptations, something listed below, or the tune itself. I will flash back to stage 2+ and run some more logs to see if it comes back.

Other things I did when I reflashed(in case someone else has the same issue),

Cleaned and lubed o-rings on MAF sensors
Lubed o rings on charge pipes, reset charge pipes
Lubed o ring on diverter valve line(intake side, on the driver side intake, right downstream of MAF),
re-tightened all the bolts on downpipes(they were freshly installed)

[Popematt02]

Another update: I reflashed stage 2+ and still having the same issues. For some reason, my car must not like the stage 2+ MHD tune. No issues on Stage 2, so I will run that for the time being.