[sean2648]

Hey all, can't talk to my shop until Monday unfortunately but this is driving me crazy so I figured maybe someone can confirm or shed some light on if this happened to them. I know there are plenty of threads on misfires/plugs/coils/ etc.

Driving on the highway the other day, downshift to get off an exit, car starts studdering, actually had my friend look up to see if I was on the rumble strips. Get off the exit, pull over, didn't have my OBD with me. Go home to grab it, read the codes, cylinder 6 misfire. I had the car towed to my house.

Did the norm, swapped the coil assembly from 6 to 5 to test coils, didn't follow. Swapped out the plug for a new one (even though they are pretty new). After I swapped the plug, new codes for multiple cylinder misfire, on 2, 3, 5, and 6. At this point going crazy. I rechecked everything, plugs are seated correctly, connections are good, torque specs are fine, gaps are correct etc.

So in my mind, injector issue. I just want to see if that's your all thinking as well before I pull the trigger on replacing them. That's all it really could be at this point right? Only hard evidence I have on it being a faulty injector is the plug is a LITTLE more black than the others. Otherwise, it's just process of elimination.

Thanks ahead of time for the input.

[sean2648]

I guess I should probably provide some background to help.

2015 335i, FBO, Conservative Tune. Car has 40k miles. New plugs were put in the car after I went FBO and tuned around 30k miles. The first issue I have had with the car since I got it. I've done all installs, maint, etc myself other than the tune.

[thejeremyman9]

Does the misfire only occur under load or all the time?

Try flashing back to stock tune and see if it continues?

[davidr3]

Like Jeremy said, sounds like your tune could be causing the misfires.

[sean2648]

I got it all figured out. Ended up being a fuel injector like I thought. Warranty covered the cost thankfully even though I was ready to DIY it.

Everything running great now, even better than before actually. Have a feeling this injector has slowly been on its way out for a bit now.

[MAKH 5]

Originally Posted by thejeremyman9

Does the misfire only occur under load or all the time?

Try flashing back to stock tune and see if it continues?

Just an FYi, keep in mind, flashing back to stock tune will only hide the problem if there are really misfires occurring as the stock tune is now where near as aggressive as the OTS tunes.

Just went through this, and my tuner said that wasn't a good idea.

[thejeremyman9]

Originally Posted by MAKH 5

Just an FYi, keep in mind, flashing back to stock tune will only hide the problem if there are really misfires occurring as the stock tune is now where near as aggressive as the OTS tunes.

Just went through this, and my tuner said that wasn't a good idea.

This is only true if the tune itself is not the problem. Unlikely, sure, but not impossible. Also, even if the tune itself is not the problem, flashing back to stock or lower stage tunes might give you hints as to what hardware is the problem based on the hardware that is being pushed more on the higher stage tunes. So, it certainly a valuable diagnostic procedure switch tunes and/or take it out of the equation.

[MAKH 5]

Originally Posted by thejeremyman9

This is only true if the tune itself is not the problem. Unlikely, sure, but not impossible. Also, even if the tune itself is not the problem, flashing back to stock or lower stage tunes might give you hints as to what hardware is the problem based on the hardware that is being pushed more on the higher stage tunes. So, it certainly a valuable diagnostic procedure switch tunes and/or take it out of the equation.

Ah ok. Got it!