S54 running issue

[sweet3]

Have you reset adaptations? I know you tried another DME, but still worth trying. Might take a few attempts to reset correctly. Maybe try another pedal too?

[moatilliatta]

New TPS sensors can be glitchy, try old ones?

Throttle swing nicely? Not catching on any clamps?

aftermarket MAF / intake?

[TobyB]

I'd be looking at live data while it's doing it, to see if there are any telltales there-

things as basic as short and long term fuel trim behavior, that sort of thing. Also inputs from TPS,

(since it SHOULD be going into open loop) temperature sensors, that sort of thing. To see what the DME THINKS is happening.

I'm mostly INPA and PASoft, because lazyyyyyy and 'just' MS43

but Romraider, Bytelogger, or... dammit, whatsit?- Test-O! might be even more helpful.


t

[E30SPDFRK]

New Crank Sensor?
Swap ICV?
Try unplugging Instrument cluster?

What faults do you get?

New crank sensor, tried 2 ICV's (issue only happens at or near WOT), haven't tried unplugging the cluster. No faults

Forgot to mention, we tried another unlocked ECU from a friends working swap and had the same issue.

[DesertBMW]

MSS54 is known to fail in weird way especially when you unplug the component and the DME is still displaying data for it

[moatilliatta]

New Crank Sensor?
Swap ICV?
Try unplugging Instrument cluster?

What faults do you get?

[E30SPDFRK]

Not E30 related, but I've been working on this for way too long now and I'm starting to get mental block. My issue:

1996 M3
S54 swap
EWS, secondary air, rear O2's, ABS, and speed limiter have been coded out
Redline adapter harness, new Z3M engine harnesses
Z3M CANBUS cluster
Rebuilt engine, completely stock other than stock-compression .020" over CP pistons
All new OEM sensors (all of them)
Custom "CAI" drawing from the engine bay with heatshield blocking fan/radiator wash
Catless headers

Full throttle below ~2500rpm, the vehicle chugs and bucks like its carbureted. Above 2500rpm, it reacts fine and has good power. If you slowly apply throttle from like 1500rpm in higher gears, the car feels like its accelerating fine until you hit around 75% throttle, when it feels like it cuts power and starts bucking.

- Vanos is entirely new, timing has been checked multiple times.
- compression numbers all within 5%
- all new plugs, coils, and injectors
- fuel pressure is perfect even during the issue
- still happens with MAF unplugged
- happens with top half of E46M airbox/MAF combo in place of the CAI

Many fault codes have been removed from the DME with coding (mostly related to components not used in the swap), but no faults pop up after the issue happens. One thing I have noticed is that the speed signal reading from the DME is wildly inaccurate (reading ~300kph at 35mph). I pulled pin 9 at the X20 connector to remove speed signal to the DME, issue is still present, redline reduces to 6000rpm (dyno mode I believe).