Chasing down cyl. 2 misfire (P0302)

[2drXmobb]

Did you clean the egr? Is the cats plugged up?

 

[alvaroemg]

Hmmm. Looking at the display, it shows 2590 misfires for #2 cylinder, but -0- for the #4 cylinder?
But back in reply #17, the #2 plug looked OK, but the #4 has the signs of oiling on it?

I would be interested to see the difference in 3 spark plugs at this time:

* #2
* #4
* known good control spark plug (ie: cylinder that never misfires)

Here are the photos. cyl 2 looks great, as well as cyl 3. Cyl 4 was a brand new plug(previous fouled plug was installed in cyl 6)

2, 3, 4

 

[alvaroemg]

Stuck valves? Dirty injectors? Have you cleaned your maf sensor ?

Valves were installed with new seals by the shop that got me the new heads. They have under 1000 miles or close to it.

Injectors are brand new, fj504 standard, as of 2 weeks ago.

Maf sensor is clean. My old started giving me low input code, purchased one on amazon and it died after 4 months. Got my money back, found one at the treasure yard in good looking condition, brought it home and cleaned it with maf sensor cleaner.

Did you clean the egr? Is the cats plugged up?

Egr, i don’t believe so, no. That wouldn’t cause misfire on a single cyl…? Would it?

Cats are not clogged, i did purchase a bottle of dpf cleaner. Guy at autozone said i can spray the cats with it and let it soak for a bit, that would clean em up but I still haven’t used it.

 

[alvaroemg]

One other point I haven't seen mentioned, check the porcelain on the plugs for cracks. I'm not saying I've done it, or haven't done it, but cracked porcelain can induce a misfire as well.

Porcelain is good on said SPs. Just checked.

 

[alvaroemg]

Did you clean the egr? Is the cats plugged up?

Cleaning egr atm, upon taking it out, i remembered i did clean it when I did the heads

 

[Road Trip]

The porcelains on the first and second photos are *exactly* what we want to see in
all 8 cylinders. If you have that look on all 8 plugs, you aren't using any oil, and you
have the compression test results you documented, then that engine should run solid.

Since you are are NOT using a noticeable amount of oil, then we have to prove/disprove that
you don't have infant mortality with the injector feeding the #4 cylinder. Normally a plug that's
carboned up like that is usually caused by excess oil getting into the cylinder?

But we have to prove/disprove a failure with the #4 fuel injector. IF the injector is being driven
for the right number of milliseconds, but for whatever reason it can't shut itself off completely
(drooling/dribbly) then this might explain the poor look of that plug.

And the only other thing I can think of would be one of more broken piston rings. But when I
state that, at the same time I can't explain the fact that you are NOT using oil to any significant
degree.

If anyone reading this has firsthand experience with a stuck fuel injector on a new FI assembly
this would be a great time to share how you proved it to yourself.

****

Cleaning your EGR valve is always a good thing, but as you mentioned the problem statement
that I need to answer is why:

* The scan tool identifies a bad #2 cylinder, but the number #4 spark plug is the ugly one?
* Why do we have a single fouling cylinder, while the other 7 are looking pretty decent?

I hope that the NEW parts haven't muddied the troubleshooting waters via infant mortality?

 

[alvaroemg]

Egr cleaned.

 

[alvaroemg]

Whats the process of testing the injector?

Prior to intake installation, i tested for leaks with injector spider installed and I didn’t see any fuel leaking outside of its housing.

 

[alvaroemg]

i checked the gap on the double platinum plug previously installed on cyl 4 and it was at 56. I gapped it to 60 and threw it back in cyl 4. Runs smoother, no cel yet, drove around the block and did some hard accelerations and no cel. Just seconds prior to pulling into drive way cyl 2 starts misfiring.

Ive been sitting in my truck and no cel yet, and misfirings have stopped reporting in dash command. Im still at 596 for cyl 2 and its been about 5 minutes.

 

[alvaroemg]

UPDATE

On a previous post a page back or 2 or maybe even 3, i had mentioned that I had driven to work with the 2 new spark plugs gapped at .045 and that the truck was misfiring, so before heading home i gapped both to .060 and the truck rode better.

Just for the heck of it, i checked another double platinum spark plug and it was gapped at .055.
I gapped it to .060 and installed in cyl 2. Started truck, revved it, went for a drive, floored it, no CEL. I checked my misses in dash command, and nothing.

Cyl 1 missed a little bit, maybe 130 misses and cyl 3 maybe 300

I’m beginning to think this truck don’t like that .045 gap on SOME cylinders which is odd and weird at the same time.

As of now, cyl 1-4 have a gap of .060 on the playinum sps. If im not mistaken, it missed more on the .045 gap, will have to double check my previous photos.

I made it to the freeway(55mph+) and cyl 2 starts missing.

Total misfires p/cyl on this drive(10min)
Cyl 1 - 113
Cyl 2 - 777
Cyl 3 - 115
Cyl 4-8 - under 5


Can sligh overtighten rocker arms cause misses?