2005 Suburban 5.3 T missing P0300 after changing plugs and wires

[project_x]

I have an '05 Suburban with 5.3 T engine.
It has 165k miles. In working to a baseline of maintenance, I put in new plugs (ngk platinum...same as were in it) and acdelco wires.
Since making that change, I'm getting P0300... With misses in 2 and 7....the ration is about 1:10 on 2 vs 7...

Where should I start to troubleshoot this?

 

[S33k3r]

If you are seeing issues on 2 and 7, swap wires from a working cylinder to 2 OR 7, and see if the code moves. If the code doesn't move, swap plugs, to the same cylinder you are testing. If the problem doesn't move, you know it isn't plugs or wires. Do the same thing to the cylinder you haven't checked. That is, check ONE cylinder at a time like this. Odds are you either have a wire problem, and/or a spark plug problem.

 

[project_x]

If you are seeing issues on 2 and 7, swap wires from a working cylinder to 2 OR 7, and see if the code moves. If the code doesn't move, swap plugs, to the same cylinder you are testing. If the problem doesn't move, you know it isn't plugs or wires. Do the same thing to the cylinder you haven't checked. That is, check ONE cylinder at a time like this. Odds are you either have a wire problem, and/or a spark plug problem.

That was exactly the approach I was going to start with.

Thanks

 

[project_x]

I let it cool down.
Switched the wire from 5 to 7 and vice versa ..
Started it up an monitored the misfires....they were gone.... On 7 and 2 ( which I didn't touch)....
So I'm wondering if the wire on 7 wasn't seated .. and the miss on 7 was somehow creating a miss on 2...which is next in firing order...

 

[S33k3r]

I'm just glad it's gone. I have a similar issue to trouble shoot, but I'm hoping to complete my diesel swap before having to do so.

 

[SilverSport]

I had a similar issue on another brands vehicle and after removing and reseating a spark plug wire the code went away never to return...mine was installer error...me...good luck with yours

Bill

 

[S33k3r]

I had a similar issue on another brands vehicle and after removing and reseating a spark plug wire the code went away never to return...mine was installer error...me...good luck with yours

Bill

I've had mine off and on -- mostly on -- since I bought it...