Chasing down cyl. 2 misfire (P0302)

[2drXmobb]

Are you pinging bad?

 

[2drXmobb]

Here

 

[alvaroemg]

2 spark plugs arrived today instead of 8. Order said all 8 have been delivered. I called Amazon and after 20 minutes of them investigating, 6 more are on their way to be here Thursday.

I gapped the 2 sp to .045 and installed in cyl 2 and 4. Started my truck and no CEL. I rode around the block and still no CEL. I did a few hard pulls and no CEL.

I felt the engine running a tiny bit rough on idle.

For the wires, I'll be ordering the NGK 51070 or the Delcos 9718Q.

I'll be leaving for a 10 day work run any day now so I'm hoping to have the new plugs and wires installed by then. Cap and rotor should be here by the time I get back, UMP DCR820X.

++ Once I have swapped all the SPs out, I'll upload a picture of what the old SPs look like in order.
++ Neighbor stated he "lost" his $800 scanner. ..

What options are there for scanners? What's everyone using? I've found this LAUNCH CRP123X ELITE on Amazon for $178. Seems pretty good and has good reviews

 

[alvaroemg]

Today I pulled the cap and rotor and this is what they look like(photos attached). I cleaned the contacts lightly with 1000 grit sand paper and throttle body cleaner.

UMP Cap and rotor, spark plugs, ngk wires will be here on Thursday.

 

[Road Trip]

Today I pulled the cap and rotor and this is what they look like(photos attached). I cleaned the contacts lightly with 1000 grit sand paper and throttle body cleaner.

UMP Cap and rotor, spark plugs, ngk wires will be here on Thursday.

I took a careful look at your sharp photos, and nothing jumped out at me. On the other
hand, when dealing with this high KV bottled lightning, the proof is in the pudding. Speaking of
which, good to hear that the 2 plugs you received have got you running without misfire or
SES/CEL light. Here's hoping that with fresh set of wires + 6 more plugs that the idle smooths
out even further.

Don't know if you already saw the construction details of the NGK magnetic core wires, but
thought I'd include the following so that you can see that these wires aren't marketing snake oil.
If you get the same kind of service that I do out of these wires then you will appreciate them for
many miles and many moons.

IMO, a big improvement over the cost-constrained high resistance only stuff that our GMT400s were originally built with.
If you are planning on keeping your truck, then you get to invest once instead of buying thrice:

You must be registered for see images attach

FWIW I ran the NGK part number you posted earlier against their web site, and it looks
like a match. (See attached.)

As for the scan tool, I just purchased one, but currently I'm ~330 miles away from the truck,
and don't want to mislead anyone until *after* I personally prove to myself that it will do what
I need it to. Hopefully the folks with true expertise in this area will jump in with their recommendations.

That's all I got for now. Looking forward to your next status report and what you uncover.

Cheers --

 

[Road Trip]

Today I pulled the cap and rotor and this is what they look like(photos attached). I cleaned the contacts lightly with 1000 grit sand paper and throttle body cleaner.

I just took another close look at your photos, and something caught my eye that
is either a cosmetic manufacturing flaw, or it's the start of the way these crab caps
blow through from the center terminal to the #3 cylinder spark path that runs
adjacent to it.

To get a better idea of what to look for when these caps burn all the way through,
check out this photo that @L31MaxExpress shared over HERE.

After viewing that photo and appreciating the crab cap failure mode, please take a
gander at the marked up versions of your photos that I attached. If the cap is
burning through, it's juuuust starting.

UMP Cap and rotor, spark plugs, ngk wires will be here on Thursday.

The UMP Cap & rotor is good news, looks like it will arrive none too soon.

And finally I was thinking about the 'many miles & many moons' comment
I made earlier. One of the things that shortens the life of a lot of spark
plug wires is all the tugging/twisting/yanking when the spark plug wire boots
weld themselves to the spark plug porcelain, especially after all that radiant
heat from the exhaust manifolds is layered on.

Once I finally started using dielectric grease without fail with every plug change,
I stopped suffering the frustration from all the above. Now the spark plug wires
always came off like factory fresh, and this was in addition to keeping misfire-
inducing moisture out of the boots.

If you follow the tips in the 3rd attachment, this will put the finishing touches on
your mid-life refresh of the ignition system. Wish the Vortec setup wasn't quite
so fussy/demanding, but in the interest of meeting the needs of added power +
tightening emissions starting in '96, the design engineers really pushed the ignition
system for max performance.

And now that we the consumers provide the final QA function for so many companies,
it's really become a chess game to keep these dizzy systems working in a brave new
world where normally every cylinder gets it's own dedicated stationary coil feeding it.

Hope this helps. Best of luck --

 

[alvaroemg]

This morning started truck to come to work and CEL came on right away. P0300, multiple cylinder misfires and truck was really bogged down, maybe running in 6 cylinders. Pulled both new sps and this is what they look like, #4 looks like detonation or burning at the core. #2 seems fine

 

[Road Trip]

Don't see any pics in your last?

EDIT: Fixed -- got it!

 

[Orpedcrow]

Here

I believe that “detonation” description should read “damaged porcelain from detonation”

@Road Trip beat me to it. I was also going to suggest a further, closer look at the intersection in the cap. Seems to be a failure mode.

You must be registered for see images attach

 

[Schurkey]

I believe that “detonation” description should read “damaged porcelain from detonation”

Detonation? I'd have said "oil fouling".