Man this is nuts! I have been so frustrated tonight. Spent a few more hours trying to diagnose, discovered the injectors that a friend let me borrow are too short on this intake, so can't entirely rule out the injectors. There is an odd noise from the passenger side though, comes in around maybe 2500-3000 rpms under load. I tried the napkin/dollar bill trick with the exhaust to check for a burns valve, and didn't show come out with any results.

Julien, any other symptoms with that misfire?

 

If I stay on it long enough the truck goes into REP mode and I have to shut the truck off to reset it and then it clears everything and runs fine afterwards. That is how I ran it at the throwdown and just haven't been home to pull plugs, valve covers, scan it, etc and see what it could be.
My first guess is the ignition wires but I'm not 100% sure yet. I will be home within the week and hopefully will get around to it soon. Just thought it was weird that there are alot of people having misfiring problems of late.

 

Hmm...mine hasn't gone into REP mode. But I haven't beat on it much since it left the dyno. Does it misfire just prior to REP mode? Only thing I haven't replaced yet is the plug wires. I ohmed a few of them out, came back with like 780ohms which google says is normal.

I was thinking the same thing, lots of people with misfire issues. Before this it was transmissions. I swear if my truck had any disease it would be full blown AIDS. lol

 

So I decided to pull a few plugs to see how they look after a few days in the engine. They might have 40 miles on them. Only pulled bank 1 because the turbo and log manifold makes the other side a pain to get to. Might pull them later when I've got more time.



#7 rich...safe to assume the broken valve spring is causing that.


Old plugs:





Same pattern, rich #7. #2 also looks a little darker than the rest.

 

Nah, I think that it's pretty much just me that hates on the Patriot stuff

To smokeshow, if you're not going to just be replacing the one spring (or getting one FOC from TSP), I'd recommend the Manley Nextek duals and ti retainers (they're listed w/o dampener). I have a thread in the Internal Engine Mod section that covers my reasoning behind this: https://www.performancetrucks.net/fo...ed-lol-481604/

As for your misfire, I'd start with the basics and do a compression and cylinder leak down test if you haven't already. Maybe try swapping some parts side by side to see if the misfire moves from #7 to #5 (I'd swap coils or wires first since they're the easiest, then maybe injectors. An injector could be stuck open or have a bad spray pattern and cause the spark plug to carbon up like yours is)

 

Guys, all spring have breaks. It doesn't matter if it's a stock GM spring, PRC, Patriot, Manley, PAC, PSI, Lunati, etc....they've all broken!

 

Soon as it cools down outside I'm going to do the compression test. Is it absolutely necessary to preheat the engine before the test? I'd rather not run it if I don't have to. I've already swapped injectors around, so its not that. Ohmed out the plug wires and they checked good, but I have yet to try a different coilpack on the driver side. Thanks for the advice

Can't ask for anything to be bulletproof once you start deviating from stock stuff, and even factory parts have their issues.

 

what do you mean by "Ohmed out the plug wires"?

EDIT: i Should say, how do you do this and what is the procedure? i know that you are testing resistance.

 

Just a basic resistance test. Looking for a wire that may have got pinched or something and now has more resistance. Just hook a multimeter up to the ends of the plug wire. Mine were all 800ohms +-50.

It was a quick test, and I didn't expect to find anything wrong. Whatever happened happened on the dyno, since thats where this mess first popped up.

 

It always misfires before REP mode and it always goes into REP mode if I stay in it when it starts to mis-fire and pop. If/when I to hear the truck popping I roll off the throttle and the mis-fires stop but if I stay in it and keep accelerating than the engine goes straight into REP mode. I gotten very familiar with the procedure!!