[mysterio]

Sorry for the novel…have to cover the whole backstory so I don’t get suggestions for things I’ve already tried.

2nd owner 2013 328i which has a little over 91,000 on the clock. I’ve got 140010 and 140410 codes for several cylinders misfiring and cylinder 4 misfire. You can clearly hear and feel the miss and it practically stalls about a minute after cold startup.

Immediately preceding these errors I had installed an Evolution Racewerks Charge Pipe, but I’ve never had a tune on the car. The install went relatively smoothly, and I test drove it without issue for a couple miles before the misfire started.

I thought, maybe it’s the meth bungs that I forgot to silicone tape. So I sealed those up good. No dice.

I swapped back to the stock charge pipe. No dice.

Do I need to do a boost leak test if this misfire is happening at idle? I would think not.

I rigged up a makeshift smoke generator using some stuff I had laying around and didn’t find anything conclusive. I’ve got a proper smoke machine on order to check again but I’ve tentatively ruled this out.

I’ve scoped the intake manifold to check for carbon buildup. It looked minimal, although I can’t be sure i looked at every valve since it’s so hard to maneuver the scope to different locations.

I’ve pulled the coils and swapped 1-4. No change.

I’ve pulled the plugs (pic attached), which only have around 25k on them. #3 looks a bit blacker than it probably should. Does this indicate injector failure?

Added clue I forgot about: Blackstone oil analysis indicated 2.5% fuel in the oil about 2,000 miles ago. I had dismissed this due to taking the sample pretty soon after a cold start, but perhaps this is more indication of injector related failure?

I’ve scoped through the spark plug holes. No obvious signs of damage on any of the cylinders, but again, hard to maneuver the scope to see everything. There were wet looking spots on a couple of the cylinders.

Anyone have any other bright ideas besides helping my indy shop make a boat payment or two?

[340iGUY]

Test for air leaks.
Change-out all the plugs and run injector cleaner through a tank.

[mysterio]

Wound up getting a proper smoke machine and didn't find anything on the intake - throttle body path. I've replaced all 4 spark plugs and injectors with no luck. Compression tested out fine.

Finally had it towed to a dealer and they found evidence that injector pulses weren't making it to the injectors from the DME so they wanted to replace it. Given the cost, I elected to DIY this with precisionecu.com. Unfortunately even this replacement DME didn't fix the issue. Going to try to replace the injector/ignition wiring harness next. My current one ohms out fine but I'm wondering if the sockets in the harness have gotten loose over time and aren't making good contact with the DME pins. It's a shot in the dark but I have found that to be the case with the brake light connectors.

Anyone have any other ideas?

[BMWILUVU]

Originally Posted by mysterio

Wound up getting a proper smoke machine and didn't find anything on the intake - throttle body path. I've replaced all 4 spark plugs and injectors with no luck. Compression tested out fine.

Finally had it towed to a dealer and they found evidence that injector pulses weren't making it to the injectors from the DME so they wanted to replace it. Given the cost, I elected to DIY this with precisionecu.com. Unfortunately even this replacement DME didn't fix the issue. Going to try to replace the injector/ignition wiring harness next. My current one ohms out fine but I'm wondering if the sockets in the harness have gotten loose over time and aren't making good contact with the DME pins. It's a shot in the dark but I have found that to be the case with the brake light connectors.

Anyone have any other ideas?

If there is evidence of electrical problems or if the charge-pipe is at fault then perhaps not but
did you ever in the life of the car get carbon cleaned off the valves and did the dealership check this?

[mysterio]

Originally Posted by BMWILUVU

If there is evidence of electrical problems or if the charge-pipe is at fault then perhaps not but
did you ever in the life of the car get carbon cleaned off the valves and did the dealership check this?

I'm not sure if the dealership looked into carbon build-up but I did personally scope into the intake runners. Can't be sure I saw every single intake port as it's difficult to snake the camera in the right direction but the ones I did see looked more or less fine.

I can confirm that the dealer did some kind of probing of the injector wiring as I see pinholes in the wire insulation. I would assume this was an oscilloscope looking at the injector pulses.

[mysterio]

Problem solved. Turns out this was a boneheaded mistake on my part One of the engine vanity cover mounting grommets dropped into the charge pipe at some point during the install. My guess is it rolled all the way down into the exit of the intercooler and then got sucked up into the #4 intake runner when I got on the throttle after the engine warmed up sufficiently. Thinking back, this is exactly when I first noticed the misfire on the post-install test drive.

I did notice this piece was missing off the engine cover, but not until getting the car back from the indy shop and dealership. I had incorrectly assumed that one of them misplaced it.

Lesson learned: make sure you account for all the pieces you took off.

[Phoenix704]

Wow...really glad that nut wasn't any smaller. Good catch.