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Discussion Starter #1
After replacing the plugs and wires on the car it started to misfire badly. After running my scan tool it's showing a P0300 error code, random or multiple cylinder misfire. So I switch the plugs and wires around and nothing seems to fix it.

Today as I'm trying to figure out what happened since there was nothing wrong before the new plugs and wires, I come upon an electrical connector just swinging in the breeze on the rear driver's side of the engine. I can't seem to find where this connector plugs in to is the problem. I'd appreciate your help.

https://imgur.com/sVVCusE
 

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Discussion Starter #3
I think that is the dod connector.

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I have a GXP, so no DOD but looking at other threads it does appear to be the DOD connector. I guess they just put it on all G8s.

I really wish it wasn't that. Now I've got to figure out what the hell is causing these misfires. Before I switched the plugs and wires there was a very slight stumble at idle and when at WOT, very slight. So I figured swap out the plugs and wires and that should fix it. Pull it in to the garage, no misfires, change the plugs and wires and now it misfires. I've already swapped in multiple sets of plugs and wires and the misfire is still there. The exhaust smells like sulfur at times too, I'm thinking a bad O2 sensor or a bad cat. I do have to check fuel pressure though too to rule out any fueling issues like the pump or pressure regulator.
 

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Yeah they put the same harness on the GXP so it has that did connector.

Check the grounds under hood (pass side front of motor to frame rail by abs, and drivers side rear block by firewall actually next to the dod connector). Also check the coil clips, sometimes the blue safety clips come out and the pins don't make good contact.
Also on my GXP I found some wire chaffing on the coil wire harness as they were rubbing something (need to look can't remember exactly). So bare wire was exposed, but never had codes guess I caught it in time... Had to wrap with electrical tape then tesa tape and move the coil wires a bit.
One of the plugs may have cracked during install. Sometimes it is hard to see.
Some plugs have screw on tips that the coil wires clip to and are a pain if not tightened beforehand. They can back off during install(Unscrew) of the plug wires, or while manipulating the wires...

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P0300 pretty much says that you have multiple cylinder firing failures. Maybe the entire side of odds or even cylinders have quit on you. Drivers side uses fuse F35-20A to power up the coils an injectors. Passenger side uses fuse F29-20A to do the same thing. They are located in the underhood fuse panel. If both OK, maybe either side master disconnect connector to the coil wire loom (located over the valve cover in the middle of the coil pack assembly is not seated/locked in position. If OK, maybe master ground wire for either side coil pack is broken or not hooked up, Drivers side at rear of cylinder head. Passenger side at front of cylinder head. Easy things to do to start your T/S
 

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Discussion Starter #6
So I fixed the misfire by going back to the stock plugs. For some reason the car did not like either set of new plugs I tried on it.

The slight stumble I was trying to fix is gone too, that seemed to be because of a couple of wires that had broken connectors in them, new wires fixed that.
 

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A few new spark plug wires and the old spark plugs remedied the issue which is great. Curious, what brand of spark plugs and plug wires did you purchase?
 

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Discussion Starter #8
A few new spark plug wires and the old spark plugs remedied the issue which is great. Curious, what brand of spark plugs and plug wires did you purchase?
Both sets of plugs were from NGK, one their new and expensive ruthenium plugs and the other their cheapest plain old copper V-Power plugs. The wires that I swapped in for the stock ones are NGK too.

Its weird too because it seems quite a few Camaro owners run the ruthenium plugs with no problem and loads use the V-Powers with no issues.
 

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Not familiar with those plugs but could the gap be off?
 

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Discussion Starter #10
Not familiar with those plugs but could the gap be off?
No, I double checked them and even had my brother confirm they were gapped right.
 
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