I dont think its an issue with the knock sensors tho since they seem to be working fine and detecting actual knock.

Are the coils hardwared into the engine harness or is there another plug that they join into ?

 

Theres a bulk connector on the coil bracket that plugs into the harbess on either side about center of the valve cover, if it werent dark id go take pic of it for ya... Are you getting spark on the right/passenger side???

 

I know where that connector is. I've taken the entire coil brackets off twice now and even swapped it with the driver's side.

I am getting spark, yet the misfire indications remain ONLY on the 2-4-6-8 head, the driver's side head has no misfire detections.

The entire coil bracket that is on the passenger side head, started the day off on the driver's side.. There has been no change in the problem even with this change.

 

Do you have a vacuum guage?? Or a fuel pressure guage???

 

You still haven't reported back on the Fuel pressure. Did you ever verify it, especially under load???

 

With him having misses all on one side, im beginning to think maybe restricted fuel rail or something with the injectors on that bank, possibly even a vacuum leak specific to that side...

 

It's 1 of the first things I asked for about 1 month ago...

I had a vehicle sit for 1 year with out being started. The fuel separated and left deposits on the injectors. It caused a misfire at idle on 1 side of the fuel rail on 2 of the injectors. I took them out and cleaned the injectors and the Issue cleared up.

Just be cause the pump was replaced doesn't mean its outputting the correct pressure at Idle or under load. You need to verify both, especially with an aftermarket replacement.

I have seen these engine run with as little as 35 PSI at idle but they sputter like hell under load and you can see the PSI drop.

 

Yeah, on 9-26 I posted that it was holding steady from idle through WOT. No change.. I do have a FP gauge, its a mechanical style that screws into the fuel rail, this is what I used when I was testing. Pretty certain the fuel pump is working fine.

Yes, I do own a vacuum gauge, but I haven't connected it to the truck.

I understand what you're saying about the truck sitting and the fuel related issues, but please understand the truck was driven quite regularly BEFORE this issue cropped up. I was driving it for weeks and months prior to the incident that triggered me to park it. Once I parked it, it sat for about a year, when I had time to deal with it, I put a new battery in it, and it fired up like I drove it the day before. The problem was/is identical to the day I parked the truck.

If it was fueling related, I believe I'd see misires all around not just on one cylinder head.

 

Ok do you have a way to enable individual injectors right?? If so, Hook up your fuel pressure guage, get pressure up, open each individual injector, make sure the pressure drop from each injector is the same....youre gonnq have to bring pressure back up after each injector is fired. As for the vacuum guage, hook it up and see how much vacuum you have and see what the needle is doing, amazing what your vacuum guage will tell you about your engine.. Did you drop the whole y pipe of just the right side??

 

Sorry I missed that you said it had 65 PSI steady at idle and under WOT.

On a return Style, the spec is lower.

It Should be between 48-52 PSI at Idle and Jump up about 8-10 PSI under load to around 60PSI

If your at 65 at idle its already over fueling in the lower range and it can not compensate when you go WOT. The injector values and related fueling tables are specked at the lower PSI.

When you go WOT. You might be maintain PSI but the Volume decrease's with the higher demand. Most Likely leaning it out in your case.

I wouldn't be surprised if this is your issue.

Check the Fuel Pressure Regulator as it may have blown through the diaphragm and be leaking as well.

Pull the vacuum hose of while its running and see if its wet or leaking.