Quote:
Originally Posted by kern417
How do they know it's a software limitation? What in the logs or otherwise shows there's physically more fuel on the table?
|
He first mentioned it in 2015, when he began developing for the B58 platform:
Quote:
Now the bad news. It looks as if BMW has placed an IPW fuel limiter in to the DME firmware. This could be an attempt to hinder flash tuners or could simply be to avoid some sort of an injector or fuel system flow limit we don't know about yet. On previous models we've altered the DME's fuel pressure signal as a back door to to raise IPW. On this model when altering the fuel pressure the DME responds by lowering it's load target proportionally to keep IPW consistent.
We can work around it fairly easily with a CANbus JB4 by dynamically altering the load back to the DME to be within its new lower range and add dutycycle to bring boost up. While we get the boost curve we want the IPW is fixed so AFR leans out.
What this means is that pump gas JB4 tuning is no problem. Race gas only tuning may get a bit sketchy at higher power levels. Maybe around 400whp.
|
Since then he has mentioned the fuel cap a bunch of times in that main JB4 thread. He doesn't go into any more details though due to the competition, but he seems confident there is a software based cap and that flashing will help.