# Random misfire



## Chris2298 (Aug 1, 2012)

Hello all. I was driving last week i my '12 Eco MT with 151K miles . It was pouring down rain and I had been driving about 20 mutes on the highway the car was at temperature. I started to go up a hill and the car stated bucking. On the next hill it started gain and the traction control light came on and the CEL flashed but didn't stay on. After the 2nd hill, anytime I would put the engine under load it would hesitate and almost stall out. I stopped the car when I got where I as going and stayed for about 2 hours. When I left it didn't start up again until he car got up to temp. This time the light came on and stayed on. I drove it the next day and had 0 issues. After a few cycles the CEL went out. Occasionally now it will miss when accelerating, but no CEL. I used Orielly's scanner and it said random misfire and #3 misfire. I am thinking it's time for a coil? Any other ideas? I am all stock except the airbox mod...and that shifter handle that adds 200h.p.... Plugs are at .028, about 15K on them.


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## ChevyGuy (Dec 13, 2014)

What plugs are you using? I think some comments have indicated that some plugs have a pretty short life. Since the problem is under load, I'm thinking spark blowout.


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## Chris2298 (Aug 1, 2012)

I believe they're NGKs.


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## cdb09007 (Aug 7, 2013)

Coppers last MUCH less than iridiums or platinums. Could also be a tear in the boots. Check the plugs, boots, and coilpack for anywhere the seal could be broken.

If you do need a new pack, they're 80 bucks on amazon, and plug and play. Don't let the dealer do it for $300.


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## obermd (Mar 3, 2012)

The CEL indicates more than just the plugs. I also wonder if you had a coil pack rubber boot failure.


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## Robby (Mar 1, 2013)

I'm with OB on this one......plug wells filling with water.

Rob


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## ChevyGuy (Dec 13, 2014)

Robby said:


> I'm with OB on this one......plug wells filling with water.


How does the water get there?


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## RIXSTER (Apr 13, 2015)

I would lean towards coil pack myself, just went through this myself.


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## Robby (Mar 1, 2013)

ChevyGuy said:


> How does the water get there?


OP indicates he was at speed during a severe rainstorm......I'm speculating water getting blown about the engine compartment may have gotten under the cover and down a plug well.

Rob


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## obermd (Mar 3, 2012)

Robby said:


> OP indicates he was at speed during a severe rainstorm......I'm speculating water getting blown about the engine compartment may have gotten under the cover and down a plug well.
> 
> Rob


So the solution for this one may be to take the ignition coil off and use a blow dryer on the coil and a rag (carefully) down to the spark plugs to soak up excess water and then blow dry them.


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## Robby (Mar 1, 2013)

obermd said:


> So the solution for this one may be to take the ignition coil off and use a blow dryer on the coil and a rag (carefully) down to the spark plugs to soak up excess water and then blow dry them.


Yes, and reassemble with silicone grease to bring the rubber seals back to life.

Rob


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## Chris2298 (Aug 1, 2012)

This issue has disappeared, so I am assuming that Rob was correct (as usual) and the problem corrected itself once the water evaporated completely.


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