HELP! Trying to diagnose misfires on n54 135i

[e82bro]

Hey there tryna find the solution to fixing misfires on my 135i.

I’m getting misfires around 50mph/80kmh then my car will a throw CEL and run like shit, I’ll turn my car off then cycle will repeat itself.

Codes: 29CD, 29CE, & 29CC are what protool is reading, I can’t figure out what’s the cause to misfires on cylinders 1&2, they’re index 12s so I doubt whether it would be leaky injectors + I recently replaced decoupling element & O rings fixing cold start misfires a month back or so.

I’ve changed coils 1&2 to 4&5 to see if the codes would change but remained the same, I’ve also pulled spark plugs cleaned, regapped and swapped them over to 4&5 but the same codes as previous popped up.

My only assumption is maybe bad index 12s but highly doubt that, or maybe incorrect installed of o rings but I used the correct device (not a pen cap lol).

Could this be a possibility that the Valve Cover Gasket is due? Coils 2&3 were wet but oil was fresh and I just done an oil change but split oil.

Where should I go from here I’m absolutely stuck now?

[alindquist]

I assume you installed injectors in same port or did you mix them? If mixed you need to code them.

[PRTSB1M]

If you setup a camera to record your tail pipe during cold-start and see a puff of black smoke, this is likely due to leaky injectors. You might also want to check grounds and injector harness for any loose or out of place connections. Agree that you should check injector coding is correct in INPA.

[e82bro]

Originally Posted by PRTSB1M

If you setup a camera to record your tail pipe during cold-start and see a puff of black smoke, this is likely due to leaky injectors. You might also want to check grounds and injector harness for any loose or out of place connections. Agree that you should check injector coding is correct in INPA.

Just found the issue, o rings weren’t tight so may have incorrectly installed, so going to replace o rings and hope it seals