n62 4.8 misfire diagnosis -- 3 weeks and I still can't figure it out -- PLEASE HELP!

[Fladventurerob]

I took out the injectors and had them ultrasonically cleaned and rebuilt. Got all new plugs and coil packs (the engine has 115k on it). Reassembled and relearned the valvetronic limits, but have been having random misfires and rough running to the point I can't drive it, nor do I think I should lest I damage something. Here's what I've tried so far:

1) I reinstalled the original plugs and coils...problem still exists.
2) I did a smoke test and a low pressure test for vacuum leaks and found a very small one in the eccentric shaft seal, repaired...problem still exists.
3) I tried unplugging and even tested a new MAF sensor...problem still exists.
4) I decided to drive it for 5 minutes after clearing all the codes again, and it says random misfires, but misfires on cylinder 2 & 6. I tested the injector signal with noid lights on both injectors cables and they are good.
5) After running the engine for 30 seconds, I was able to feel the exhaust manifold on #6, and it was hot. I was also able to reach #5, and it was neither hot nor cool. (EDIT for anyone that sees this -- The cylinder numbers in the book, are not the cylinder numbers in the computer. The computer shows cylinders by firing order! So the #2 in the firing order is actually cylinder #5 which was the cool manifold pipe)
6) I unplugged both #2 & #6 injectors during noid testing, and the engine didnt run any worse or better.
7) With everything hooked back up, I unplugged the cable from the driver side eccentric shaft sensor which is the side I had to disconnect when removing the fuel injectors, and the engine didn't really noticeably run any worse but I almost want to say it ran slightly better (but that could just be me)

I am at my wits end and my wife is pissed that the car has been sitting in the garage for 3 weeks after what was supposed to be a quick weekend job...but now with no end in sight. I'd actually like to drive it again and stay married . I have an ICOM and all the software, if anyone has any helpful suggestions, PLEASE PLEAAASSSEE helppppp! I would be forever grateful! (Also, if you really know what you are doing and are in the Orlando, FL area, please shoot me a PM)

[jclausen]

How about just taking to to a BMW shop and having them figure it out

[Fladventurerob]

It may come to that, but I prefer to learn things and someone here might have the info I need...so I figured I'd give it one more shot. Also, the price could be $500, or they could not figure it out, just like me, and $5000 later, still have no answer.

[White94RX]

Sounds like you're missing a large portion of the diagnosis process. Have you done a compression test? What about a leak down test? Have you checked the timing? Have you inspected the intermediate shaft and levers for wear? Are you sure the DME is firing the injector and coil?

[Fladventurerob]

@white94RX I didn't do any of those things because these issues didn't exist prior to the injector cleaning.

I did find the issue however. What I didn't realize is that the codes referring to the cylinder # aren't referring to the diagramed cylinders, but instead, the firing order. So cylinder #6 misfire is in fact, firing order position #6 and you need to cross reference that with the cylinder #.

After I figured this out, I did a noid light check, and both fuel injectors are not getting power. Probably caused my having to extensively move (per the Bentley manual) the harness during the fuel injector swap.

After a little more digging, I found out that these cars are notorious for engine wiring harness issues, so much so that BMW sells a repair kit for it.

That being said, as of now, my plan is to buy a wiring harness and swap it out for the one that's in there now. I'll probably do the valve cover gaskets at the same time.

If anyone has any opinion on this please let me know! Thanks!!

[White94RX]

What kind of code reader are you using? I've never seen one that displays the firing order cylinder number and not the actual cylinder number.

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[cleaner123]

yikes.two different threads. looking at a 550 today, thought i'd do a little studying.

[Murderede60]

Vanos solenoids need degreasing or replacing. Try this first because it’s cheap to free and it causes that.