2002 chevy Silverado misfiring

Hey car talk community! I have a 2002 Chevy Silverado 2500 HD and over the past year I’ve had misfires only after its rained very hard or its humid out. the spark plugs and wires have all been changed and it has seemed to help with the rain but in the humidity its still running bad. does anyone have any suggestions?

Try replacing the ignition coil.


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Believe a 2002 Silverado will have 2 banks of coil packs. I’m not sure what to add, but I don’t think there’s a way to just change the coil. I do see the logic, on an older rig, though.

If this is the 6.0 liter V8, it has 8 coils

You can change coils individually


I think you’re correct. I just changed the valve covers on my 4.8 recently and removed 4 coils as a unit. But I believe each coil can be replaced individually. I admit I jumped the gun there, sorry Tester.

OP are any codes given? Could help determine which coil, if any, has an issue.

Correct, truck has 4 individual coil packs. When I go to start truck after a rain when it’s humid, my whole drives side bank looses spark. Gives a p0300 code. After a rain is the only time it runs like poop

Yes it is the 6.0 with 8 individual coil packs

RockAuto has the ignition coils for as low as $14.00 each



If the whole bank loses spark, you might take a look at the electrical connections. There’s one connection for all 4 coils (you can unplug one connector and remove the entire set of 4 coils as a unit on the bracket they sit on) - so that might be something to look at.

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Ask your shop to check on the visual spark quality on the misfiring cylinders when it is having this problem. If the spark is ok, consider the possibility that there’s a problem with the electrical harness to the injectors on that side. If the spark proved ok, a noid-light test might be and easy way to do a diagnostic.

I grabbed a spark tester from the local parts store already but haven’t had it on me during a misfire. I have reason to believe the injectors test good during that time due to how much extra unburnt gas I have coming out the tail pipe