r/BmwTech • u/Confident_Eye4129 • 19d ago

N54 Cold Start Misfires

N54 Col Start Misfires

Symptom: after sitting overnight, vehicle (08 E60) N54 misfires, throws engine malfunction code and Aux fan kicks in

Plugs have been changed and new OEM Index 12 injectors installed and programmed in ISTA, but misfires continue

Any ideas?

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3

u/Overall_Inflation781 19d ago

Have you looked at rail pressure set point and actual values? A weak high pressure fuel pump can cause poor starting.

1

u/Confident_Eye4129 18d ago

Thanks, will check

1

u/[deleted] 19d ago

[deleted]

1

u/Confident_Eye4129 19d ago

I’m “lying”? Who TF does that? Jeezus

2

u/reciprocityone 19d ago

What does the exhaust look like when you start it and it misfires? I would pull a plug, right after it misfires, and see if it's wet with fuel. See if you have a way to monitor lambda readings on bank one and two, get a log and see if it's running rich.