Hello again everyone!
Was driving the other day and started getting general misfire codes. Got it home.

decided maybe it was time for new plugs and wires. Replaced with new STI cables and champion 7070s.

cleared codes. started back up.

started getting misfire codes again P1300, P0306, P0308) and strong rotten egg / sulfer smell.

I have never had the head gaskets done. Was hoping I didn’t have to start taking everything apart. Before I do all that and potentially waste time and money, wanted to check in here - any thoughts?

 

Are you sure you got the wires in the right order? If so, try swapping the new parts on 6 and 8 with the parts from other non-misfiring cylinders. If the coils are still in the stock position start with the spark plugs, then do the wires, then swap the coils left to right, then the injectors until the misfire moves (one at a time of course, test in between). Those two cylinders are on different coils but different towers on each coils so they could both be bad and if you swap left to right the fault will move. Good luck.

 

Can you tell us exactly what cylinders? Knowing that can help us isolate if its a fuel, spark, or compression issue.

 

The original codes were for general misfire and the the 6th.

After I did the wires I noticed same codes again, and then the 8th on and off. But full disclosure, I had some trouble getting the 8th new wire back on the coil. I did get it to "click" but could not tell if something got messed up so I am not ruling out that the p0308 is on me... but the p0306 and random misfire (p1300) have been consistent. The coils were replaced a few years ago with new genuine bosch.

 

Good (and easy) to do compression test before dismantling heads, but diagnose by swapping components (per Extinct) first.

 

Also getting p0300 on and off. Haven’t had a chance to swap components yet. I’m pretty sure I have the plugs in the right place but will be able to check this weekend. I also read about checking injectors and crank shaft sensor. Thoughts? I don’t think I’ve ever looked at the injectors in this truck before. Any tips?

 

Extremely low probability it is injectors, more likely it is low compression than injectors and I would put that at a one in 25 chance (my personal experience). Def not Cnkpos sensor, that is an on or off situation.