HELP! I do not want to go to the stealership- X5M Misfire

[dlucas589]

Hi All,
So I bought my 2013 X5M off another forum member here in April

Ever since I bought it there has been some sort of rough idle or stumbling acceleration followed by CEL and Reduced Engine or Drivetrain malfunction

First issue was mainly rough idle throwing cyl 6 misfire code
Replaced all 8 plugs and all 8 coils (Eldor)
Did nothing
Replaced cyl 6 injector that was absolutely toast (sooted) and issue resolved for 1-2 months

Now I am back getting cyl 6 misfire and power management code. Primarily stumbling under any sort of acceleration over 2K RPM
Dug into all 5-8 bank of injectors this time to find cylinder 5 toast but 6-8 still good (clean) Replaced cyl 5. Checked plugs on 5 & 6 both look normal not wet with gas

Also replaced all CCV lines and all of them were broken and also replaced both filtered air duct

Previous owner ran Velos tune but said he returned it to stock before selling

Took to local BMW mechanic who couldn't figure out what could be wrong.
We replaced the battery that apparently was put in in 2018 without being coded to the car. He did leak down and compression test and said everything looked fine...

Used ISTA to test fuel pressure and all is well there

Here are the only ideas I have
-ECU issue- driver for cyl 6 is toast. thinking of sending it off for testing
-Harness issue
-Cylinder issue (major issue) that could rear its ugly head soon and destroy engine?
-Vacuum issue
-idk what else

I really would like to figure this out so I do not have to be at the mercy of the stealership. I know this topic has been discussed ad nauseum but I cannot seem to pinpoint a solution with everyones posts on the subject.

Thank you so much in advance. anyone who helps me find the root cause here will get a nice venmo Christmas gift

[TwinSnailz]

Have you tried swapping spark plug on 6 ?
Correct spark plugs? I once bought spark plugs that was made for n63 with bmw logo and it cause the same misfire you have. Bought some bosch plugs from Rockauto and back to normal.

[dlucas589]

@twinsnailz
Plugs I got from FCP
BMW ZR5TPP33 Spark Plug - Bosch 0242145515
The mechanic said he swapped the plugs and nothing changed
Maybe will try swapping 6 over to other bank.

Do these plugs come pre-gapped and no need to change gap?
I cant imagine the gap though that would only affect 1 cylinder..

[TwinSnailz]

Try swapping plug 6 to other and see if the misfire jump. They do come pre gapped but compare and check them again. Swap the coils too while you’re at it.

My spark issues was it would idle fine and drive normally fine. But once over 2k rpm with a bit more throttle it would throw a misfire and check engine light.
The Bmw stamped logo spark plug even had the zr5tpp33 etch on the side of the plugs which i think is weird that it didn’t work.

[dlucas589]

I'm tempted to try the ngk 91874 since its iridium and supposed to be better than bosch.

Will try swapping tomorrow and report back.

The truck has begun to misfire not only at low and high RPM but now at idle. Feels like the engine is getting punched every couple seconds.

Any chance a bad injector on the 1-4 bank is causing cyl 6 misfire?
Those are the only injectors I have not seen yet and am tempted to tear into those as well

[Sophisticated Redneck]

Ista has extensive testing capabilities that can test each injector as well has misfire testing (has to be run when engine is cold). The tests are not easy to find as ista is not intuitive but if you dig you will find them. If your Injectors are not index 12, I would replace them all even if they test good. Anything below 12 are absolute junk. Also check the make sure all of the bolts on the wiring harness for the injectors/coils are secure to the valve cover, this is a grounding point for the injectors and coils. If everything checks out and want to test the drivers, grab a portable oscilloscope and compare the waveforms, link below.

https://www.amazon.com/YEAPOOK-Handh.../dp/B07XBL4BTL

[dlucas589]

Sophisticated Redneck
Thanks for mentioning Ista. I spent several sessions running diagnostics and misfiring testing. Cyl 6 was the only cylinder that was outside of their normal range I believe range was -150 to 150 and cyl 6 was an anomoly at 700ish. The rest were good. All injectors are index 12. Sprayed some electronic contact cleaner in the coil plug of cyl 6 earlier today, maybe that will do something...Going to check harness for tightness tomorrow but should be good since I was just in there replacing the injector.

Can you provide more info on how to do the testing with the oscilloscope? thnx!

[Sophisticated Redneck]

Originally Posted by dlucas589

Sophisticated Redneck
Thanks for mentioning Ista. I spent several sessions running diagnostics and misfiring testing. Cyl 6 was the only cylinder that was outside of their normal range I believe range was -150 to 150 and cyl 6 was an anomoly at 700ish. The rest were good. All injectors are index 12. Sprayed some electronic contact cleaner in the coil plug of cyl 6 earlier today, maybe that will do something...Going to check harness for tightness tomorrow but should be good since I was just in there replacing the injector.

Can you provide more info on how to do the testing with the oscilloscope? thnx!

Here is a good primer:

and there are many more on youtube, but basically the easiest way to test would be to setup the scope to record a good cylinders waveform vs Cylinder 6. There are also videos up on using that scope that will be better to watch then anything I could type here. Its a decent little scope, nowhere near 100mhz like advertised (more like 50) but you don't need that type of bandwidth for injector testing.

Also double check the leakdown on that cylinder again just to make sure its not something like a bad valve or ring.