[bmwaddictt]

Hi everyone, hope you are all keeping safe during these difficult times.

My 428i idle's very very rough, almost like its about to stall. I'll give a little back story. I've been running Bootmod3 Stage 1 93oct for almost 10,000kms now all stock and around 5000kms with a catless downpipe and everything was working and driving like a charm. The car then was due for a major service at 65,000 kms with spark plugs oil change etc all required, everything was allgood till the car came up and eventually popped up with 'overdue 500kms' and i started the car one day and it was like it was about to stall. This happens everytime i come to a red light as well and go to a full stop, car is about to switch off, rpms are very rough. I took the car into BMW my service advisor told me that I did not need to remove the tune so I did not. They serviced the car but they didn't see anything wrong with the idle. Stupid if you ask me. As soon as I jumped back in the car started it, immediately I realised... Very stuttery rough start, and if you just tap the accelerator pedal a little and let go the car is almost about to turn off. What could be the issue? There is no codes that come up, but sometimes a transmission ESG error comes up code CF1531 when the vehicle is switched off after a tune update idk if thats normal. I'm really worried. Even flashed it back to stock, still the same problem... Please someone help!! Thank you


Edit: guys could this be an engine knock?? Please see video

[muniz_ri]

I would start by checking the spark plug gap. Improperly gapped plugs will cause a rough idle...not to the extreme that you described but still worth checking.

[bmwaddictt]

Originally Posted by muniz_ri

I would start by checking the spark plug gap. Improperly gapped plugs will cause a rough idle...not to the extreme that you described but still worth checking.

Originally Posted by muniz_ri

I would start by checking the spark plug gap. Improperly gapped plugs will cause a rough idle...not to the extreme that you described but still worth checking.

Hmm right I'll get this checked. By the way, when changing the Downpipe, does the 02 sensor need to always stay disconnected? I think my mechanic did not remove these. The car has been fine ever since the service light came on at 500kms though?