So i have an e87, 120i with the n46b20b engine.
I have the problem that its misfiring on multiple cilinders.
Symptoms are that idle is rough, when slowly pressing the gas it runs ok(not good, but not bad either) and backfires when letting off(small pops/bangs)
When stepping on it, it almost sounds like its suffocating/drowning(not really sure which one. Fault codes are p0300, p0301, p0302, and p0304
Ive replaced plugs and coils, no difference.
Replaced valvetronic motor and calibrated it, no change.
I replaced the timing chain, used the special tools in order to set it correctly, no change
Tried unplugging o2 sensors, no difference
Replaced the maf, no change.
Swapped injectors with known good ones, no change.
Compression and leakdown were both good
Fuel pressure is good, wiring is also good.
Im at a loss as to what it could be, since it pretty much tried everything i can think off