[thatblue92]

Hey everyone, I have a 2008 BMW 335xi and I have had a misfire under load for the past few months. It started out only at high RPMs but now I can barely drive the car, as it misfires badly when I give it more than 40% throttle and it goes into boost. I’ll list everything I’ve done down below, I’m super lost and don’t know what to do. Only modifications are intakes and downpipes, I’m on an MHD stage 2 tune but it still misfires on the stock tune

-New Spark plugs and Ignition Coils
-Car came with index 12s that I tested for leaks and put new seals on
-new LPFP and HPFP
-upgraded mosfets
-new valve cover, and I’ve basically resealed the entire motor
-New intake manifold gaskets
-The intake valves looked fairly clean, I think they were cleaned not too long ago. No serious build up.

The car only throws me Cylinder 6 misfire codes, nothing else. I have no clue what it could be, has anyone seen something similar?

[E9XIZM]

Hey, if I was you I'd start with the basics and do a process of elimination. Try moving the coil to cylinder 5, if not I'd check the injector itself. You can try to move it to another cylinder and recode and see if the misfire follows.

It can also be that the injector bore is ovaled causing the injector to not seat tightly on the head, if your cylinder 6 injector feels slightly wobbly or loose when you remove the retaining bracket and fuel line that may be your issue. Hopefully not but search the issue and you can see it can be an issue on these engines.

Good luck!

[thatblue92]

Originally Posted by E9XIZM

Hey, if I was you I'd start with the basics and do a process of elimination. Try moving the coil to cylinder 5, if not I'd check the injector itself. You can try to move it to another cylinder and recode and see if the misfire follows.

It can also be that the injector bore is ovaled causing the injector to not seat tightly on the head, if your cylinder 6 injector feels slightly wobbly or loose when you remove the retaining bracket and fuel line that may be your issue. Hopefully not but search the issue and you can see it can be an issue on these engines.

Good luck!

If it is the ovaled out injector bore, is there anything I can do to fix that without replacing the head? Like an oversized seal or something? Also, if that were the case, wouldn’t my compression be lower in that cylinder? Because on the compression test all the cylinders came out to 145. Also I have moved injectors and coil packs around to no avail, so that can’t be it

[335i54n]

145 is kinda low, 4-5 revolution only, if you have to keep cranking to get there is not good