P0308 Misfire Code while road tripping

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Burby

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2016 with 40K miles. Was trailering around 4000# on a 1000 mi trip and the check engine light came on. A quick stop at Autozone to check the code and it showed a misfire on cylinder 8. I jiggled the plug wire a bit and after a new tank of gas the light went off. It came on again on the return trip without the trailer and was flashing this time (that is bad). The flashing stopped after 5 minutes. The light did not come on again for the remainder of the trip.

I can't say for sure this is trailer related because most driving is short trips and this was the first extended drive in months.

Gas mileage did not drop. Was not sluggish or showing any other symptoms. It is an intermittent check engine light and the only constant is that it is on Cylinder 8.

First step I will try is replacing the plug wire. I am dreading this because Cylinder 8 is the hardest to reach and work on. Anyone else hear of a similar issue? Seems like this should not happen at such low mileage.
 
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OR VietVet

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What should not happen and then what does happen may not make sense at times. You can do the wire but I would also do the spark plug, whether it is hard to get to or not. Before you do this you could swap a plug wire off another cylinder and see if the misfire code follows the wire or stays at #8 cylinder.
 

Fless

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What should not happen and then what does happen may not make sense at times. You can do the wire but I would also do the spark plug, whether it is hard to get to or not. Before you do this you could swap a plug wire off another cylinder and see if the misfire code follows the wire or stays at #8 cylinder.

Then if the miss stays on #8, swap the #8 coil with another cylinder's to see if it follows that.
 

Doubeleive

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#8 is easy, just a use a short extension, short ratchet and then a breaker bar, all you have to do it get it loose and then you can take it out by hand, everybody wants to over complicate #8
 

Rocket Man

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It’s either the plug, wire, coil or injector so follow along with the above advice and swap components one by one to another cylinder to see if the issue follows one of them. Injector would be the last item I would swap. The injector harness is also a possibility however unlikely.
 

wjburken

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#8 is easy, just a use a short extension, short ratchet and then a breaker bar, all you have to do it get it loose and then you can take it out by hand, everybody wants to over complicate #8
I’ve had good luck with a deep well socket with a 3/8 drive, 3/8M to 1/4F adapter, 1/4M to 3/8F adapter and a 3/8 ratchet. Gets you out past exhaust manifold and not into all the A/C stuff.
 

Doubeleive

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I’ve had good luck with a deep well socket with a 3/8 drive, 3/8M to 1/4F adapter, 1/4M to 3/8F adapter and a 3/8 ratchet. Gets you out past exhaust manifold and not into all the A/C stuff.
as long as you can clear the exhaust manifold then just slide a breaker bar over a 1/4" ratchet and crack it loose, I use a piece of 1" galvanized pipe
 

Rocket Man

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as long as you can clear the exhaust manifold then just slide a breaker bar over a 1/4" ratchet and crack it loose, I use a piece of 1" galvanized pipe
Or a regular depth socket ( forget the size) that fits over a 5/8” plug socket ( plug sockets will accept a regular socket on their top instead of inserting an extension) and then a 3/8” drive ratchet. Perfect length.
 
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Burby

Burby

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I'm actually more worried about pulling the cylindrical heat shield, boot and wire. And doing so without messing it up.
 
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