misfire on multiple random cylinders(P0300) both banks.

Coil packs were replaced ~4k miles and 9months ago(I assume they wouldn't go bad that quick)

Ignition module looks to be the newer silver one "A 000 150 02 58 Q1".

The misfires seem to be most prevalent at cold startup but happen at warm idle as well.

Any thoughts? I am guessing ignition module from what I have read. But I am worried the coil packs could have died as well.
Thanks,
Will

 

Try cleaning out the crankcase ventilation hardware at the front of the LHS camshaft.

Try changing to a different brand of fuel.

Does it just happen at idle?

Nick

 

It is most noticable at idle as I get a rough idle.

It is also happening at other times as I notice a loss of power and when I come off WOT what sounds like backfires.

edit:
Since you mention fuel. I did have a bottle of techron in the tank. I just filled up with a new tank last night and haven't noticed any difference yet.

 

if the techron doesn't work i'd check the ignition module. sometimes they have intermittent shorts.

 

The Techron was in the last tank. The new one is normal 93 octane gas. Any way to check the ignition module?


The check engine light went off today. It seems to be fine now with the new tank of gas. Perhaps it was bad gas or my engine doesn't like techron...

 

it could've taken time for the techron to work. my mechanic was somehow able to check the ignition module. he is at the dealer with all the required diagnosing equipment.

 

Well wasn't bad gas. Came back after a few more starts and stops.

Dealer replaced plugs.
Now dealer is replacing fuel injector in cylinder #9.

Hopefully that is the end of it.

 

look at this, yes it is possible to test the ignition module

https://mbworld.org/forums/6125328-post9.html

 

I experienced something very similar. It turned out to be the fuel pressure sensor.

https://mbworld.org/forums/m275-v12-...d-problem.html

 

My check engine light came on with misfires on 6 of 12 cylinders. I did bg fuel injection cleaner and added BG44k in tank. Cleared codes. All was good for 3 weeks then check engine light came on again. This time misfire on cylinder 11 and 12 only. Also dirty left bank air intake. It is definitely better but car hesitates and check engine light will flash at full throttle. Any suggestions? Getting ready to check fuel pressure

 

Mine was the bad fuel injector(#9). Once they replaced it the engine was back to it's normal self.

 

I will look into that. So fat my fuel pressure is only 4 bars or 55 psi. That looks like fuel pump. My fuel filter also looks dirty. I will replace fuel pump and fuel filter and see if that solves the problem.