GEN 1 Misfire - 4 cylinders

[randyb]

2012 6.2l supercharged. 91,000 miles.

Looking for any assistance. I have updated tunes with a reputable tuner but we were having problems getting it to run correctly. It was suggested that I check the plugs only to find that most of them had been fouled on the top 8 and the bottom 8 were all wet. Therefore, plugs were R2. It is also important to note that the previous owner had a shop tune the truck after changing the plugs, however upon inspection of those plugs they were gapped at .044 instead of .027-.030 as it is supercharged. Unfortunately, this was not known while my tuner and I were tuning the truck. Before changing the plugs the truck ran well but very rich and always had that unburnt fuel smell which my wife continued to remind me about.

I know its a long story but up-to-date I have changed all 16 plugs, coil wires and pellets. My findings today were that cylinders 1, 2, 3 and 4 are all having misfires but 5 - 8 are having no issues. In my last data log this afternoon after swapping coils between Cylinder 1 and 2 and switching coils between C3 and 4, I had the following misfires reported per cylinder and the truck only ran for about a minute.

Cylinder 1 = 7 misfires
Cylinder 2 = 380 misfires
Cylinder 3 = 37 misfires
Cylinder 4 = 362 misifres

Any thoughts? Is is possible to have 4 bad coils all on the same side? Truck ran extremely well except for the stinch of the exhaust until we started messing with tuning. Oh and its good to mention that I have changed back to the factory tune that the truck came with and still having the issues above.

HELP

 

[randyb]

 

[MTF]

Have you unpluged the three PCM connections to look at all the little pins for corrosion?
You may need to open up the plugs so you can look at the back side inside the plugs.

 

[randyb]

Have you unpluged the three PCM connections to look at all the little pins for corrosion?
You may need to open up the plugs so you can look at the back side inside the plugs.

Alright everyone. Still troubleshooting but as of this morning have done the following:
Compression check and 1 - 4 cylinders are all in the 185 - 200lb range so those should be good and takes out mechanical issues. I am starting to look at all connectors and wiring this afternoon. I have unplugged the three PCM connectors and all looks well there so it maybe a chaffed / rubbed wire between ECM and coil.

I will entertain all thoughts though.

 

[1BAD454SSv2]

Check oxygen sensor wiring , and any wiring laying on exhaust . How old are the sensors? You could try swapping bank 1 with bank 2 and see if problem moves. Don't bother with the ones behind the cats

 

[CoronaRaptor]

The wiring for the ignition coils are known to be fragile, especially on s/c trucks, look for rubbing on the wiring or stretch marks. Just curious why the coils were never changed, just as a maintenance item anyway? I mean obviously the previous owner didn't know how to tune one properly. Who installed the s/c?? Might of been running crappy since it was installed, who knows?

 

[MRV99]

I read in another thread that this was due to a plugged cat.

 

[CoronaRaptor]

I read in another thread that this was due to a plugged cat.

wouldn't all 4 be the same misfires then? IDK?

 

[MRV99]

wouldn't all 4 be the same misfires then? IDK?

Not necessarily. What ever it is, it is only effecting one side.

 

[CoronaRaptor]

Not necessarily. What ever it is, it is only effecting one side.

Very true!