Technical LOG REVIEW: Weird AFR Bank Issue

tan_rich

Specialist
Feb 6, 2018
89
18
0
Ride
335is
Hmm thats interesting then, pulling from past experience when i shifted my banks would switch running lean when shifting. Changing secondary o2s solved this for me.

What is really worrying is that your one of your banks go extremely lean going near redline. Your fuel pump low and high pressure seem to be good. Have you gotten any codes from this? Possible throttle surging when coming to a stop?

What plugs are you running? Reading on a different forum for someone that had bank1 running super lean and getting superknock codes. Their issue was resolved when swapping to new NGK 95770. For the gap, i'm not sure how much you should gap at the power level, maybe someone else more experience can chime in.

You can swap bank1 and bank2 plugs to see if it follows but at your power level, id rather just get new ones.
 

suspenceful

10 Second Club
Aug 1, 2017
559
591
75
Ride
2015 M3, 2008 135i, 2009 335i
Whoa - timing in Cyl5 went to zero and stayed there right before your AFR went to 20. Looks like Injector 5 could be the problem.

Like someone else said, cylinder 5 is prone to noise at high power levels. It's always dropping. I don't think it's related.

Hmm thats interesting then, pulling from past experience when i shifted my banks would switch running lean when shifting. Changing secondary o2s solved this for me.

What is really worrying is that your one of your banks go extremely lean going near redline. Your fuel pump low and high pressure seem to be good. Have you gotten any codes from this? Possible throttle surging when coming to a stop?

What plugs are you running? Reading on a different forum for someone that had bank1 running super lean and getting superknock codes. Their issue was resolved when swapping to new NGK 95770. For the gap, i'm not sure how much you should gap at the power level, maybe someone else more experience can chime in.

You can swap bank1 and bank2 plugs to see if it follows but at your power level, id rather just get new ones.

I haven't gotten any engine codes from any of this. I literally just replaced my NGK 95770 with another set of the same plugs as routine maintenance. Both gapped at 0.022" with PR ignition coils.

My tuner sent me a new flash to see if we can make any progress. Otherwise, like you said, I'll probably swap plugs and wires across banks and see if it moves.
 

Jeffman

Major
Jan 7, 2017
1,620
1
629
0
I understand the whole Cylinder 5 being super sensitive, bur jeez, it’s timing really crashed from 6 to zero and never recovered. I’ve never experienced that and I do my own tuning.
 

suspenceful

10 Second Club
Aug 1, 2017
559
591
75
Ride
2015 M3, 2008 135i, 2009 335i

Still haven't figured it out. I swapped primary O2 sensors and the issue stayed on bank 1. I uploaded a few different flashes from my tuner and no difference. It doesn't do it all of the time, only some of the time. So it's hard to trace down. All new plugs and wires. It's a weekend car so I'm messing with it as my motivation allows.