[ZTZ1010]

So as the title states, i've been having an obnoxious yet consistent misfire on cyl 3 for the past few weeks. Of course I tried replacing all 6 spark plugs (first dealer trip), in addition to swapping coilpacks between that cylinder and another. misfire remained in cyl 3 so I figured it was the injector. Dealered twice, once for injector and once because they wanted to try replacing the coilpack, yet the misfire stayed in cyl 3. It essentially occurs every time I drive the car, and makes it pretty much undrivable ( having to stop/restart motor every time). Conditions don't matter, as it happens across the board both with tune and without.

I've read about carbon buildup causing misfires, but from what I've gathered, it won't necessarily trigger a single cylinder as consistently as I'm getting them (everytime I drive). Similarly, I've seen hints at dirty vanos solonoids causing misfires, but I know nothing about whether or not that's accurate in regards to a single cylinder. I assume if it was a bad O2 i would see misfires across the entire bank, instead of an individual cylinder.

I'm dealering the car tuesday (fourth time in a month for the same problem) but I'd like to have a list of places to suggest they start. Any clues what else could trigger a consistent cylinder misfire besides the aforementioned typical clues? For reference, i've got 37k miles on the car and am FBO/Meth.

thanks,

Zach


EDIT: Forgot to mention I've been getting a limp mode/engine malfunction in higher gears at lower RPM if i go WOT... I think this is my turbos starting to go (30FF thrown, actuators not sealing causing a boost leak) but figured it may be worth mentioning

[Simple5]

car is a 09 with 2-3 yeard of driving around and being FBO you may have a good amount of carbon in your valves.. I would rule everything out before having to remove all mods and taking to the dealer...

[ZTZ1010]

Originally Posted by Simple3

car is a 09 with 2-3 yeard of driving around and being FBO you may have a good amount of carbon in your valves.. I would rule everything out before having to remove all mods and taking to the dealer...

As far as carbon buildup goes, is it likely that an individual valve would typically be worse than others? My thinking was that if my buildup on cyl3's valve was bad enough to be triggering consistent misfires, I'd at minimum see a single misfire on another cylinder from comparative buildup...

Luckily my dealer is mod friendly and I'm under warranty. I think the walnut blasting will be the first item on my list, since I'm just going to press them to fix/replace everything it could be. 4 times in 3 weeks is excessive, so I want to make sure I address all possibilities. Thanks for the idea!

[BES335xi]

Is the injector coded in correctly?

[ZTZ1010]

Originally Posted by BES335xi

Is the injector coded in correctly?

dealer did it.. my tech is very knowledgeable and precise so I can only assume so...any way to check?

[Simple5]

Do some research... also read where it could be solenoids or cam lifters... dont quote me on that though... there was a huge thread on it but im toolazy to search Definitely check out the valves... at 37k miles you are about due...

[BES335xi]

Yea there is a DIY on coding and changing the injectors, i think i have one posted on this forum too, im on my phone so i cant link you, but do a quick search and go check it liteterally takes u 10min tops..

[ZTZ1010]

Originally Posted by Simple3

Do some research... also read where it could be solenoids or cam lifters... dont quote me on that though... there was a huge thread on it but im toolazy to search Definitely check out the valves... at 37k miles you are about due...

I'm the one who should be ing for it anyways . I'll check it out, I appreciate the advice!

Originally Posted by BES335xi

Yea there is a DIY on coding and changing the injectors, i think i have one posted on this forum too, im on my phone so i cant link you, but do a quick search and go check it liteterally takes u 10min tops..

Didn't even consider that! Unfortunately I don't have the appropriate cable (or a PC besides my netbook) in order to test with INPA. I'll make sure my tech looks into it tuesday, though. Would be an easy solution!! Thanks

[GeorgiaTech335coupe]

LPFP?

[ZTZ1010]

Originally Posted by GeorgiaTech335coupe

LPFP?

never thrown a fuel related code... possible even withstanding that?

[135Hoser]

I have the same issue (misfire on cyl 3) and am running FBO+Meth, have done coils/injectors/plugs.

My next step is going to be valve cleaning. 38k km's on the odo.

[ZTZ1010]

Originally Posted by 135Hoser

I have the same issue (misfire on cyl 3) and am running FBO+Meth, have done coils/injectors/plugs.

My next step is going to be valve cleaning. 38k km's on the odo.

yours as prominent/consistent?

[135Hoser]

Originally Posted by ZTZ1010

yours as prominent/consistent?

Damn near every time I push it past 4500 rpm in 3rd/4th, or a long pull in 6th.

To the point now where I don't even let off when it's misfiring. Pulled on some subaru who thought he was hot stuff and blew past him while the engine was missing on cyl #3. I found it to be hilarious.

I also ensured my injectors were properly coded today, and they are.

I've switched away from Husky E10/94 Octane (run it in all of my other tuned cars) to Petrocan 91. Wasn't able to get a misfire on the way home, but I didn't bag it that hard.

I'm also thinking that one of my widebands might be on the way out for bank1 (cyl 1,2,3) Robert at Vishnu thought it might be an issue when I sent him logs.

So it's either going to be:

I was running out of fuel (shouldn't be, because I only see misfires on ONE cyl)
Valves are starting to gum up (plausible, maybe cyl 3 just has it worse due to head flow/design)
o2 sensor (I don't know enough to understand why it would read cyl 3 rich/lean and not others)

[benzy89]

I don't know if would be your o2 sensors cause wouldn't you be getting for the entire cylinder bank then (which would cause misfires on multiple cylinders, not just a specific one)?? My o2 sensors were backwards and it caused misfires on all the cylinders in the specific bank I was getting the error code for. The fuel quality also doesn't explain the misfires cause (once again), it would cause non-specific misfires -- Not like cylinder 3 gets shafted on the octane quality while everyone else (1,2,4,5 + 6) gets the good stuff.

Is it possible the Voltage/Knock sensors need to be replaced for that specific cylinder?? And because they're broken/not working, that the DME has restricted the activity of that specific cylinder as a preventative measure?

[hemi to e90]

sounds like carbon actually

[cstavaru]

Try a compression test...could be engine damage (piston rings, valves). There are some small cameras that can be introduced inside the cylinder through the sparkplug hole and you can then see the state of the piston/cylinder.

[Jeff@TopGearSolutions]

With almost 40K on the clock it could be carbon build up.

Some guy just posted his car with 35K approx and they were gunked up pretty good.

[GRLPWR]

Make sure the injector has the decoupler on it. I had similar misfires and it ended up being all of the injectors were missing this piece. Also, if you have a tune, make sure it's connected properly. Seems I've read somewhere someone had a cyl 3 issue and it ended up being a defective tune. I recently had a carbon cleaning (82k mi) but never had misfires b/c it needed cleaning. The SES kept coming, don't remember what codes it was throwing, but pretty sure it didn't single out a cylinder.

[Rotorocious]

Originally Posted by GRLPWR

Make sure the injector has the decoupler on it. I had similar misfires and it ended up being all of the injectors were missing this piece.

i found at least 2 of my injectors were lacking this piece.
Damn dealers

[hemi to e90]

im lost as to how you make sure your injectors are coded.

[Todd135i]

Originally Posted by hemi to e90

im lost as to how you make sure your injectors are coded.

Do a search for N54 injector coding. It's on all the main sites

[ZTZ1010]

Just to update, I dropped my car at the dealer this morning. Made a list of the suggestions and spoke to my tech about the possibilities. He's active on this forum (has a modded 1M) and had actually seen this post (i thought that was funny). Interestingly enough, after I cleared the codes last time, I checked this morning to see what else had come up. I ended up with full bank 1 misfires (cyls 1,2,3) which I had not seen before. I guess this is good as it gives me a few more options as far as diagnosis is concerned...

Originally Posted by 135Hoser

Damn near every time I push it past 4500 rpm in 3rd/4th, or a long pull in 6th.

To the point now where I don't even let off when it's misfiring. Pulled on some subaru who thought he was hot stuff and blew past him while the engine was missing on cyl #3. I found it to be hilarious.

I also ensured my injectors were properly coded today, and they are.

I've switched away from Husky E10/94 Octane (run it in all of my other tuned cars) to Petrocan 91. Wasn't able to get a misfire on the way home, but I didn't bag it that hard.

I'm also thinking that one of my widebands might be on the way out for bank1 (cyl 1,2,3) Robert at Vishnu thought it might be an issue when I sent him logs.

My syptoms are nearly identical. let me know if you figure out a solution.

Originally Posted by benzy89

I don't know if would be your o2 sensors cause wouldn't you be getting for the entire cylinder bank then (which would cause misfires on multiple cylinders, not just a specific one)?? My o2 sensors were backwards and it caused misfires on all the cylinders in the specific bank I was getting the error code for. The fuel quality also doesn't explain the misfires cause (once again), it would cause non-specific misfires -- Not like cylinder 3 gets shafted on the octane quality while everyone else (1,2,4,5 + 6) gets the good stuff.

Is it possible the Voltage/Knock sensors need to be replaced for that specific cylinder?? And because they're broken/not working, that the DME has restricted the activity of that specific cylinder as a preventative measure?

According to my tech, voltage/Knock sensors would more likely than not trigger a specific fault for themselves. I'd also see consistent misfiring of a specific bank, rather than an individual cylinder. Although this morning I saw bank 1 misfires, it doesnt explain the single misfire for cyl 3 that I had been experiencing, especially without additional faults.

Originally Posted by Jeff@topgearsolutions

With almost 40K on the clock it could be carbon build up.

Some guy just posted his car with 35K approx and they were gunked up pretty good.

I was hoping it was carbon buildup, but my tech said the only individual cylinder they've ever seen throw a misfire for carbon has been cyl 5. He put the request through for approval (I guess BMWNA has to approve the walnut blasting under warranty) and I think thats where we're going to start.

Originally Posted by GRLPWR

Make sure the injector has the decoupler on it. I had similar misfires and it ended up being all of the injectors were missing this piece. Also, if you have a tune, make sure it's connected properly. Seems I've read somewhere someone had a cyl 3 issue and it ended up being a defective tune. I recently had a carbon cleaning (82k mi) but never had misfires b/c it needed cleaning. The SES kept coming, don't remember what codes it was throwing, but pretty sure it didn't single out a cylinder.

I'm positive the decoupler/injector coding has been done correctly. I'll check the tune, however I'd be surprised if this was the case and no other faults were being detected. Tune was changed (15ohm board swap done by Terry) in early March, and misfires didn't start until almost two months later.

Originally Posted by cstavaru

Try a compression test...could be engine damage (piston rings, valves). There are some small cameras that can be introduced inside the cylinder through the sparkplug hole and you can then see the state of the piston/cylinder.

This is the next step if none of the above seem to fix the issue. My tech said that with FI motors cyl/piston damage is less likely, but it's not something we're taking lightly or ruling out.


Any other ideas?