Misfire - ignition cylinder 6/7 limp mode

[Lozza47]

Hi all,
I recently purchased a 2011 M3 and have had issues with cylinder 6 & 7 not firing. Car is constantly in limp mode, engine running very rough as if 6 & 7 not combusting at all. No power.
The codes are:
002758 - ignition cylinder 6 controlling electrical diagnostic
002759 - ignition cylinder 7 controlling electrical diagnostic

I have tried the following:
- Swapped coils around on 6 & 7 to other firing cylinders
- Brand new plugs on 6 & 7
- Checked voltage and coil plug connector
- Checked injectors seated properly
- Reset codes, adaptations and battery disconnected

No luck so far.
Before I picked up the car from the dealer, they did a valve cover gasket change.
The dealer isn’t coming to the party just yet to look at the car so taking it into my own hands.
Another thing, I can hear a whistle from the plenum, same side as the cylinders throwing codes. Would a plenum leak lead to codes like this?
Any help would be much appreciated.

[amrazM]

check the ground on the valve cover of the bank that is misfiring. I assure you its loose

[tdott]

When you say you swapped coils, did you swap them with cylinders that are not mis-firing? Just wanted to be clear, sounded like you just swapped 6&7 around which wont help.

[Lozza47]

Originally Posted by amrazM

check the ground on the valve cover of the bank that is misfiring. I assure you its loose

I'll check that, thank you.

Just to clarify, is it this ground?

https://ibb.co/jzQvKtH

[Lozza47]

Originally Posted by tdott

When you say you swapped coils, did you swap them with cylinders that are not mis-firing? Just wanted to be clear, sounded like you just swapped 6&7 around which wont help.

Yes, sorry that was unclear. I swapped them with cylinder 1 & 5 which were firing okay.

[linnadawg]

I just solved mine. It was only cylinder 3 for a while. This morning I had all kinds of misfire codes and the entire passenger banks fuel injectors were turned off. I scoped the passenger side ignition coil control wires and they all had random voltage spikes, which usually indicates a bad ground. Removed the ignition coil cover and the ground at the rear of the valve cover was loose. If you look at a wiring diagram it’s the ground for the suppression capacitor with all of the orange wires. Even though it’s a ground for all 4 coils it gave me a cyl 3 activation code for the longest time.

[Lozza47]

That ground cable was loose indeed. All fixed thanks for the tip guys.