N63 Misfires - replaced everything - still misfiring (SOLVED)

[jfandl]

SOLVED: (See thread #6) I have my N63TU with a misfiring problem. It was misfiring on multiple cylinders. Reported low fuel pressure on Bank 2 so I replaced the HPFP on bank 2, eliminated the issues on that bank but continued to report an issue with Cyl 3 misfire. I had already replaced all spark plugs and new coils. I put new fuel injectors in Bank 1 (Cyl 1-4). Verified rail pressure on bank 1 is good.

Started it up again and it continues to report cyl 3 as misfires and it shuts down the cylinder. I moved coil from 3 to 4, no change. I put a new plug in 3, no change. At this point Cyl 3 has a new coil, new plug, new injector and still misfires.

I'm stuck at knowing how to resolve this. All new plugs, coil packs, and fuel injectors on cyl 1-4, problem still exists, runs very rough.

I have 100K miles on the car and it's always been well maintained. Any ideas what to check next? (I'm thinking the DME could be suspect but I'd have to buy an oscope to check).

[Fknid]

Compression test?

I’m not sure where to get them but there are devices that plug into the coil plug and they light up to show that the coil wiring is working.

[tfunk88]

I haven’t heard of it causing misfires, but many other issues and since I saw you have a faulty steering angle sensor code…how old are your batteries? Again, haven’t heard of dying battery causing misfires, but…just thinking outside the box since you’ve tried the 3 obvious culprits (spark plug, ignition coil, injector)

Also…how is the wiring for ignition coil on cylinder 3? All insulation in good shape?

[jfandl]

Originally Posted by tfunk88

I haven’t heard of it causing misfires, but many other issues and since I saw you have a faulty steering angle sensor code…how old are your batteries? Again, haven’t heard of dying battery causing misfires, but…just thinking outside the box since you’ve tried the 3 obvious culprits (spark plug, ignition coil, injector)

Also…how is the wiring for ignition coil on cylinder 3? All insulation in good shape?

Good catch on the steering rack. That happens when the battery gets too low from diagnosing or coding things without a charger, especially after the car sits for more than a week. I have to put the front wheels in the air to reset the steering rack, just haven't done it yet. The battery is 4 months old.
Wiring to the coil packs looks perfect, no visible insulation issues.
I didn't run a compression test.

I've ordered a oscope and coil on pack probe to check the spark. I'm hoping that will show me if spark is or is not the issue.

[nedrobmas]

You got a borescope with dual view?

[jfandl]

SOLVED: I finally got the O-scope and was starting to check things when I found the problem. Apparently some of the coil plugs go in to the coil with ease and others have to be pulled in with some extra force so the plug goes all the way into the coil connector. I noticed some were 100% flush while others have about a 5mm gap. Once I popped the plug cover up, pulled in the electrical connector all the way (felt resistance from the rubber seal), started it up and everything came back to life with no issues. So it seems in the end it was my error not making sure the electrical connectors fully seated to the bottom of the plug.

Lesson learned: Make sure that you push the electrical plug all the way into the coil, not just when you feel resistance. I hope this helps someone avoid the simple mistake I made. Here's a photo of the plug not being pushed in all the way.

[shimmy23]

sometimes a tiny bit of dielectric grease is helpful on the rubber boot of the coil pack.

thanks for posting the resolution!! not enough folks follow up in their threads.

[tfunk88]

Duuuuuuude…glad it was something simple, but…c’mon, nah 😜

Glad you figured it out and that it was an easy…and inexpensive…fix!

[Fknid]

Originally Posted by tfunk88

Duuuuuuude…glad it was something simple, but…c’mon, nah 😜

Glad you figured it out and that it was an easy…and inexpensive…fix!

Everybody’s learning.

Thanks OP for coming back and updating us. I’ll be checking this first if I have issues.

[tfunk88]

Ha yeah, I know, it’s just good natured teasing lol

[jfandl]

Thanks for the support guys because yes, you're right, most people tend to not come back after the issue is solved and update the thread. I figured it's good to give back, even when I should have easily caught this issue earlier.

[musa]

I wish i saw your post earlier and would have given you a pointer. I ran into the exact same issue on my E92 with N54 engine. Fortunately I noticed the connection issue as soon as the misfires started happening.