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Originally Posted by GeorgeThe4th
Good morning all, wondering if anyone with the N55 has dealt with a misfire on a warm start. Car starts and idles fine when hot and cold. If there is a delay in time between me last shutting it off while hot and starting it then it will misfire on multiple cylinders when it comes down from its high idle. The missing only lasts for 10 seconds or so before the car heats up again. Even then sometimes I will throw it in gear and it will misfire again but harder since it is under load. Seems to correct itself pretty quick and has not stalled yet. I do not have a CEL or codes. I have replaced plugs and coils recently, hasn’t made a difference. I’m thinking upstream o2 sensor because of the symptoms. My thought is on a cold start it doesn’t do it because it’s running open loop for a longer time and not reading off the semi faulty o2 sensor until it’s warmed up. On a hot restart, it doesn’t because the sensor is still hot. Warm start motor is warm but sensor is cold, car reads off the o2 sensor earlier than cold and gets a false reading and misfires until the exhaust warms it up again. Just my thoughts and would appreciate any insight anyone has. Thank you!
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Did you figure it out what is the issue, I have same exact issue on my N55 and I changed new OE injectors, oem plugs, oem coils, valves intake cleaned and all seals replaced , oem vanos solenoids, OEM O2 sensors, OE HPFP, OEM airflow, OEM valve cover, replaced throttle body with a used one, car updated, new adaptation, new engine body power control, used fuel module and programmed to the car, smoke test twice and no leak and I sill have this issue.., any update would help, Thanks