New plugs, inj, pr coils and still getting mis-fires!

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InnovativeAuto

Specialist
Mar 14, 2018
63
Need some help figuring out my mis-firing problem. I am trying to get my car tuned after installing a set of Pure stg2 but getting mis-fires in cyl 5/6.

I have tried new plugs, pr coils, walnut blast, and new injectors. I am still getting a check engine light and mis-fire codes when I hit around redline. The only thing I can think of is my dual-mass causing false mis-fires? I had thought this happened at high power though. I’m only running around 16-17 psi. Any help or recommendations would be appreciated!


 
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MattGu40

Private
Jan 29, 2018
28
i found the first and even the second version of PR sparkplug wire very hard to put in location have them clicking, What sparkplugs and what gap.

.022 is recommended Dielectric grease on sparkplugs insulator and plug boot should help
 

InnovativeAuto

Specialist
Mar 14, 2018
63
Ngk 95770 gapped at .022, also tried .018 with no change. Used plenty of dieelectric when installing. Mis fires also happened with new Eldors. Swapped around coils and still get same results. With the PR kit on, it does not go into limp mode.
 

gmagnus7

Specialist
Dec 3, 2018
84
Hmmm. If your dual mass has more wear that usual (or defective) it could have more internal play, causing the misfires earlier than expected. The fact that it only occurs at redline, and the back two cylinders close to the flywheel makes it sound like it could be a possability. Not sure though and would be an expensive thing to try and replace without knowing 100%.

There can be so many little things with these cars. When I bought mine, the guy had replaced two injectors but didn't install the decouplers. That caused them to misfire on those cylinders sometimes and once I installed the decouplers the misfires went away completely.
 

The Convert

Captain
Jun 4, 2017
1,117
When I bought mine, the guy had replaced two injectors but didn't install the decouplers. That caused them to misfire on those cylinders sometimes and once I installed the decouplers the misfires went away completely.
Good way to destroy a cylinder head too!
 
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works

Private
Mar 1, 2018
34
Hmmm. If your dual mass has more wear that usual (or defective) it could have more internal play, causing the misfires earlier than expected. The fact that it only occurs at redline, and the back two cylinders close to the flywheel makes it sound like it could be a possability.
I'm having this exact issue as well, stage1 turbos with Motiv flexfuel and I'm getting misfires on 5-6 cyl. The current diagnosis is definitely the 12y old DMFW, I'm thinking of going m-factory single mass, most likely with the 550i clutch still.
 

InnovativeAuto

Specialist
Mar 14, 2018
63
Yea I just replaced my clutch a few months ago with a 550i. Kicking myself for not doing a single mass! X-clutch twin disc will be going in soon!

Looking at this old post I am pretty sure it’s the dmfw causing the misfires. It was even happening to guys with stock turbos (read last page).

Not sure if it’s ok to post links to other forums but here’s a good read. Looks like good ol Shiv found the problem:

 
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InnovativeAuto

Specialist
Mar 14, 2018
63
Have not checked the valve cover, is there any write ups how to check it for internal cracks?

I have an upgraded PCV valve but my head ports are not blocked. Maybe a good time to go external and plug ports.
 

JimboFresh206

Sergeant
Jan 29, 2018
264
pull the oil cap, and smoke the intake manifold?

Curious about this, because suspect the same on my VC.

not sure if this is the way, but seems KISS and logical.

Timing flat lining on cylinder 5 right here.

I would pull the VC regardless, as its easier than the trans, inspect Replace/Reinstall. But.... I think the DMFW is also somewhat suspect here.
 

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Rob09msport

Major
Oct 28, 2017
1,708
Monroe CT
I noticed slight laziness on hitting 234 lambda on bank 2 I believe was. I to changed perfectly good injectors thinking one was lazy so I went to index 12 even though mine only had 20k on them. I also noticed high rpm deviation on stft like I saw on your log. Everyone said know but logically oil vapor entering head ports under vac would cause afr to read off little. As far as log I isolated the condition by staying under vac for few min and my readings on everything were perfect then if I stayed on boost for little then pay close attention to log right when transitions back to vac got deviation. This will show any variable which in attributed to valve cover allowing crank case gas into the head ports . If you get an external crack it will be much more noticeable. Also the fact you note cyl 5 and 6 if you are getting oil vapor that can lower octane drastically.
 

turbohugh

New Member
Nov 13, 2018
6
IF you haven't done so you may want to go to an external PCV and dual oil catch cans. This includes plugging the holes in the head. Getting into higher horsepower levels and having our oil contaminated intake charge could get funky. I wouldn't be running upgraded turbos without dealing with our poor PCV system, especially if you're not going PI .
 

fmorelli

Colonel
Staff member
Aug 11, 2017
2,458
Virginia
Mis fires also happened with new Eldors. Swapped around coils and still get same results. With the PR kit on, it does not go into limp mode.
I'd be surprised that he'd have two discrete electrical issues at 5 and 6 with stock coils.

Filippo
 
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