[Meeegaaa_TRON]

Hi everyone, I have a 2011 335I xdrive that I am getting a code for cylinder 3 misfire. This car has a catless down pipe, cobb exhaust, cai, diverter valve, fmic, and a mhd tune. When I bought the car I was told they had already changed the coils and plugs but weren't sure if the gap was correct. Car runs good but at idle you can feel the misfire as well as when you get into full boost (14.5 psi) it misfires.

Just trying to get ideas on what you guys would do? Do I change out everything again? Do I just start simple and change the plug, then coil, then possibly injector? Let me know what you guys think or have done before? Thank you!

[TheGoodTheBadTheUgly]

Originally Posted by Meeegaaa_TRON

Hi everyone, I have a 2011 335I xdrive that I am getting a code for cylinder 3 misfire. This car has a catless down pipe, cobb exhaust, cai, diverter valve, fmic, and a mhd tune. When I bought the car I was told they had already changed the coils and plugs but weren't sure if the gap was correct. Car runs good but at idle you can feel the misfire as well as when you get into full boost (14.5 psi) it misfires.

Just trying to get ideas on what you guys would do? Do I change out everything again? Do I just start simple and change the plug, then coil, then possibly injector? Let me know what you guys think or have done before? Thank you!

The things you should look at when misfiring on a tuned or modified N54/N55 are mainly: 1) Spark Plugs, 2) Coils, 3) Fueling (If on multiple cylinders), 4) Injectors.

Unless you have an upgraded turbo and an adapted agressive tune, you don't need to gap the spark plugs.

It has been noted by many users with tuned N55s that their replacement coils and plugs do not last nearly as long as the one that originally came with the car. Do you know which coils and plugs you are running and how much did you roll with them since they were changed?

The first thing I would do, since you don't need to wait and buy other parts, is to start by swapping the ignition coil on cylinder 3 with the one on cylinder 2 and to see if the misfire will change to cylinder 2. If it still misfires on cylinder 3, It probably means that it is the spark plug in that cylinder. To confirm you would switch the spark plug in cylinder 3 with the one in cylinder 2 and put back the ignition coils to how they originally were, so you eliminate possible failure of the combination of spark plug 3 and ignition coil 3.

[Meeegaaa_TRON]

ok, thank you I will start there!