CrispyBacon

Was doing some highway pulls and got superknocking codes on all of bank 2 going about 140km/h WOT. I was logging the pull and noticed bank 2 leaned out quite a bit and spiked up to 234 before coming back down to a super-lean mixture (30-60) while still being at WOT. Same thing happened the other day but with bank 1. I am running N55 spark plugs which are 1-step colder and they are maybe 1-2 months old. My HPFP seems to spike during the superknock as well so I'm not sure if that has something to do with it. Would this be an injector issue? O2 sensor issue? Faulty spark plugs? I'll have my logs linked below on DataZap.

Logs: https://datazap.me/u/crispe/log-1643...20-21&hg=15-16

donpb

Did you throw any BMW codes or I-drive notifications?

CrispyBacon

30ED -DME: Superknocking, cylinder 1 (can't remember the other codes but i had superknock 1-6 appearing like this)
---- -DME: Superknocking, cylinder 2
---- -DME: Superknocking, cylinder 3
---- -DME: Superknocking, cylinder 4
---- -DME: Superknocking, cylinder 5
---- -DME: Superknocking, cylinder 6

These were all shadow codes and didn't cause any limp mode or CEL but it was obvious when it happened because power was cut and I could feel the shaking.

These codes seem to show up intermittently but I haven't had either of these codes triggered recently. Replaced downstream bank 1 O2 sensor less than a week ago.

• 2C31 (11313) - Lamba probe in front of cat 1, trimming control

• 2C6B (11371) - Lambda probe behind catalytic converter, system check

donpb

Seems odd with that many cylinders reporting. What fuel have you been using?

CrispyBacon

Running 91 octane, this was on ACN91 tune to be safe and it still reported superknocking on all cylinders. I've tried running 93 with 91 tune and still same thing so I don't think the fuel is the issue.

Note: I should mention this is on MHD Stage 2+ ACN91 tune

twh

Let's see. You put the wrong plugs in the car and you're running a tune and it doesn't work right? Put it all back to stock and start there. Fix the problems, and then leave it stock.

CrispyBacon

When running a tuned N54 it's better to run a 1-step colder spark plug like the bosch ones used in the N55. Using the stock ones can cause detonation due to overheating.

Source: https://bmwtuning.co/bmw-n54-spark-plugs-guide/

donpb

I assumed everything was working great for a while, or did it only start occurring post MHD Stage?

CrispyBacon

No, it happened when I was running stock but with the added power it's much easier to trigger what ever causes the superknocking, since it's happening on an entire bank at a time would that indicate an O2 sensor issue?