Shame you didn’t just replace the wires first. The plugs could have been crappy looking simply from the missfire’s.

Those missfires will over time wreck a catalytic converter…….then the dredded P0420 code haunts…..


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Didn't know that. The NGKs are single prong.


Neither the plugs or the wires should've needed changing based upon mileage. I'm just glad it was not a more expensive issue.

The 96 I had had iridium plugs when I bought it and it ran fine.

Shame you won’t know if it was the wires or the plugs that fixed it. I’ve had wires and coils go bad and had your symptoms.


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I believe the factory recommended service interval for spark plugs is 30k miles because it is a waste spark ignition system (meaning each cylinder sparks twice as often). Dual electrode is recommended because it's a waste spark system as well.

Yes, the dual electrode plugs last so much longer. I run iridium tipped single electrode plugs and they only last around 25K miles before they are tossed in the garbage. The waste spark system just destroys them so fast that the gaps open up and start to misfire. I have forced induction at a high boost so it's an unfortunate must for me, but for anyone else there's no reason to run a single electrode plug. I know that parts stores sell them as an 'upgrade' but in this case it is a downgrade. The DENSO or NGK stock dual electrode copper plugs can get well over 100K miles.

The *correct* NGK plugs are dual electrode. From the factory, one bank got Denso plugs and one bank got NGK plugs. The correct model from either manufacturer will work well. Sounds like it was just bad (wrong) plugs.

-Charlie

Quick update, hopefully the final one regarding this issue.

I barely drive my truck, since like over a year ago, before gas prices even rose. It's been roughly 2,900 miles added since I changed the spark plugs.

Well, today I experienced some light stuttering / studdering while making a quick run, while slowing down coming to a stop and idling at a light. Barely noticeable after acceleration, but noticeable.

I'm going to change the plugs again, to install dual electrode plugs.

For reference, the correct part numbers for the dual electrode spark plugs are

Denso K16TR11
-Or-
NGK BKR5EKB-11 (3967)

I'm using NGK, if I don't post again in this thread then all is well.

If anyone watches TheCarCareNut on YouTube, he is local to me. I'm going to have him inspect the truck as soon as he is able, expected sometime in June. I'm not confident in my engine anymore. Maybe I messed it up by running single electrodes for 40k miles.

Unlikely that you messed anything up permanently, I've been running single electrode spark plugs in my engine for 8 years. They only last about 25K miles though as it's only got one ground instead of 2 and the waste spark system fires them twice in every combustion cycle.

Well if they work fine then that doesn't really reassure me because doesn't that mean there's another problem other than the spark plugs that would be causing my issues?

I installed the dual electrode NGK's today. The plugs I removed looked pretty bad, but don't really have the experience to say for sure how 2,900 mile plugs are supposed to look. I'm wondering if my engine is burning oil badly.

Truck is scheduled to be inspected by TheCarCareNut this week.

If you can post a photo of the old plugs, specifically a close up of the electrodes (can be all in one photo) the spark plug palm readers on here can tell you your engine's future.

This is what mine looks like at (I think) 60k miles on the plugs and 270k on the engine:



Worn (expected) electrodes, minor tan build-up, minimal oil staining on the threads, normal coronal discharge staining on upper ceramic.

-Charlie