I would take it for a spin and intentionally make it skip for an extended period of time. Then check the header tubes with a non contact thermometer. Did you do anything to the truck before you parked it for the winter? Just to make sure, has this problem only happened this year?

 

Did you ever figure the problem out?

 

Soo... Did you ever pull the heads to check the lifters?? I am really curious as to what could be causing this issue your having. It sounds like something really simple.

 

UPDATE

Put it all back together with the fresh injectors, new 2bar map sensor, and fuel filter, ANOTHER new set of plugs and guess what? Same damn thing!


I also moved the wideband bung from bank 2 (passenger side) over to bank 1 (drivers side) but have not gotten a chance to test drive it yet.

One weird thing, i drove about 30mins to a shop to have the bung welded in and the truck drove fine, did not mis, hesitate or anything unless I tried to lean into the throttle. Then it would misfire and back fire like usual. This is different than recent drives because at one point it was running so poorly it was barely drivable. This time you couldn't even tell anything was wrong until you gave it at least 50% TPS and put a load on it.

Sorry Dewey, i just have not had time to put the misfire tunes in yet because i have to setup my scanner to log misfires, current, and history, and i just have not had time to mess with it at all. If its not raining, my goal for doing that is this coming friday, i'm leaving work early.


Summary:

Truck misses under almost all circumstances....very small hint of a misfire during idle after truck is up to temp.

Misses under light load after up to temp
Misses under moderate load (60% tps) at all temps

HpTuners log shows 0 KR, no misfires, no codes, no CEL

No check engine light (and it does work)

changed plug wires twice
changed plugs 3 times
changed coil packs
injectors
O2's
checked for broken valve springs
leak down test
compression test
fuel pressure is perfect
changed MAP sensor
changed fuel filter


Someone please just steal this ******* thing

 

Where are your coils mounted? I see you have a rail mounted pressure regulator. Did you move the #5 cylinder coil? The wire can hit on the regulator, and wear through. Just a thought maybe it is giving you a weak spark.

 

This started after you broke it out from it's winter hibernation? And before that it was good? So it's gotta be something that effected by just sitting and not being used? This kinda blows...

 

Sounds like a bad MP122. Send it to me for testing.

I also have a 122/112 exchange program.....

 

Well, see the thing is, it always had a ever so SLIGHT top end mis, like at the top of 1st and 2nd gear right before the shift, although, it was very, very subtle and most riding in the truck could not even feel it or notice it.

THIS problem described in this post, yes it did just start after winter hibernation.

 

I guess thats possible. When i had the coil packs all disassembled recently to paint them i did not notice any messed up wiring and i was looking over the wiring pretty closely. i check again right near the fpr though. thx!

 

When's the last time you checked your oil? It'd be a PITA but if you could get a look at your intake runners...