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).
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).
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