Misfiring, fixed, came back a month later. changed spark plugs, coils, and injector

[Gotulukn]

I have a f83 M4 thats on a stage 2 tune on 100% e85. My NGK 97506 had about 20k miles on 93 pump gas and 10k miles on full e85. from what I've searched on these forums, its time to change them out, but it drove fine completely fine, wish I didn't change them out.

A bmw mechanic did a valve cover gasket replacement and installed "BMW High Power Spark Plug" NGK SILZKBR8F8S (from FCP euro) since the forum say its better for flex fuel s55's, gapped at 0.020. When I got the car back (93 octane tune) the car drove fine normally around, but would misfire heavy under hard throttle, at 4-5k RPMS, with check engine light.

Codes 140001, 140010, 140601, 150610, multiple misfires, fuel injection is switched off, combustion misfire cylinder 6 etc. I would have to erase DME codes, and car will drive fine again unless I went hard on the throttle.

Mechanic figured it was a stuck/failed injector or bad coils. I bought new coil packs since I have 82k miles. 6x Dinan coil packs and a new injector in cylinder 6, the old coil pack on cylinder 6 look pretty rusty. and the car is STILL misfiring, but now cylinder 5.

We figured lets just put in new spark plugs, installed the tried and true 97506 (SILZKBR8D8S) gapped at 0.022. MISFIRES are gone! The car is driving great and strong, after a 93 pump tank, I flashed back to my full e85 tune from RK-tunes, 3 fun tanks of e85 later, it's now misfiring again, but with no misfire DME codes. I even intentionally floored my car and let it misfire but no misfire codes are showing up on my MHD. I'm only getting 118002, 118102, mixture control: Fuel-air mixture too rich, (which I always get on full e85).

My spark plugs went bad already? Bad e85? Anyone got suggestions, or I have to buy a 3rd set of spark plugs...I have the 6x flex fuel plugs I can send back to FCP, for new ones, but they caused my car to misfire initially, unless the new ones I received were actually faulty..

[E30_Bastard]

Which spark plugs and at which gap are you installing them? This system has high tolerance.

[Gotulukn]

Originally Posted by E30_Bastard

Which spark plugs and at which gap are you installing them? This system has high tolerance.

Currently the 97506 gapped at 0.022, with 1k miles on them. It drove strong for couple tanks of 93, and few tanks of e85, now misfiring under full throttle at ~4K rpms, but it doesnt throw any codes


Just before this I had the mechanic install OEM bmw high power spark part#12120042724, people say its better for ethanol, but works fine with gasoline as well, gapped at 0.020, it caused misfire at 4-5k RPM full throttle with misfire codes, brand new out of the box from FCP euro, I'm not even sure if I want to use their free warranty replacement, as this plug didnt work at all for my m4..

[Junnn]

I've seen someone got the same issue because of E85 fuel. Maybe you will want to double check the injectors?

[Gotulukn]

UPDATE: I changed the spark plugs myself, so I can check the plugs. Few things I found out. I asked for 97506 plugs with 0.022 gap, but they were gapped cyl1 0.025, cyl2 0.24, cyl3 0.26 and the rest were 0.025. The last plug in cyl 6 had this weird string thing when I pulled it out, it was touching the electrode, but it was flimsy and I was able to blow it off. The plugs overall looked ok for 1000 miles of use..



I installed brand new "BMW OEM NGK SILZKBR8F8S" plugs gapped at 0.022. The car started up great, good idle, I didn't hear the heartbeat misfiring sound. Drove it around until reaching operating temperature, before I went on it.
93 octane gas, stage 2 catless by the way,
With the gas pedal to the floor, it misfires and won't rev past 4-5k RPMS STILL!!!!! If I give it 60% throttle and drive spiritedly it can go to 7k rpms no issues..

Worst of all is that now no check engine light ever comes on. So if they were bad injectors 4k rpm is the key area where it misfires? I also read somewhere that someone said his flywheel was the cause of his misfire? Anyone have any tips before I just throw more money at this

[Joy15779]

gap 0,20

[M Vier]

I hear you. I have the same issue. I hope someone can find a solution to this.

[TR930]

Are you on stock fuel system?

[hellokitty]

Might be a leaky or clogged injector at this point. Try replacing injector 5.

[Gotulukn]

Hey guys I figured out my misfiring problem while under full throttle + mid to high Rpms with no check engine light.

It was the Dinan coil packs. Didnt want to think that would be the culprit, bought Delphi coil packs and my car is great again. Please dont buy into the 10% more output for the Dinan's.

side note sorta:
There was some loud whistling sound coming from under the hood a couple of weeks ago, mechanic showed me something very interesting, when he unscrewed the oil cap, it gave a hissss sound (releasing the pressure) and the whistling stopped! Didn't know that was a symptom of a A CRACKED valve cover! after replacing that, I crossed my fingers it would fix the misfire due to some vacuum seal issue or something, but it didn't. So i just went ahead and bought new delphi coil packs. I've read that another guy had an issue where a bad coil pack didnt send a CEL! NGK F8S plugs at 0.022 gap, running 100% e85 no issues!

[Track/S]

Originally Posted by Gotulukn

Hey guys I figured out my misfiring problem while under full throttle + mid to high Rpms with no check engine light.

It was the Dinan coil packs. Didnt want to think that would be the culprit, bought Delphi coil packs and my car is great again. Please dont buy into the 10% more output for the Dinan's.

side note sorta:
There was some loud whistling sound coming from under the hood a couple of weeks ago, mechanic showed me something very interesting, when he unscrewed the oil cap, it gave a hissss sound (releasing the pressure) and the whistling stopped! Didn't know that was a symptom of a A CRACKED valve cover! after replacing that, I crossed my fingers it would fix the misfire due to some vacuum seal issue or something, but it didn't. So i just went ahead and bought new delphi coil packs. I've read that another guy had an issue where a bad coil pack didnt send a CEL! NGK F8S plugs at 0.022 gap, running 100% e85 no issues!

This happens when you buying Chinese parts painted red, on s55 only OEM or Eldor (B58) coils.