Major misfire problems.

[crzy8mnky]

I ended up recalibrating the MAF to the 98 one and that problems seems to have gone away. I'm still getting the p0200 and p0300 codes though, with both 6 and 8 misfiring quite a bit. 5 and 7 are misfiring a little bit, but I'm not sure that it is enough to trip the code. I'm going to pull out the plugs and clean them up, and then make a test harness for the injectors so that I can connect both 6 an 8 to the computer without going through the original harness. Perhaps I damaged the harness when I was rewiring things. I pull a 5.3 harness out of the junkyard today, so if it turns out the stock wiring is damaged, I will replace it with the 5.3 harness.

[crzy8mnky]

I took off the intake manifold and there was oil on the inside of the o ring on both cylinders 6 and 8. Bad PCV valve?

[George C]

As long as you use stock pcv system you'll have oil

I still say fuel supply is your issue

[Chevydillan]

Where is the harness from or did you modify it?

[crzy8mnky]

Fuel pressure at the rail is in the right range and the injectors were just cleaned and flowed fine. However the 6 and 8 plugs were carbon fouled when pulled out. I don't know what else to test for in the fuel system. The harness is the modified 5.7 harness. Noid lights showed all 8 injectors were being pulsed and I have 12 volts on the pink wires to the injectors, along with .3 to .5 ohms on the ground wires to the computer. I even swapped in a wire directly to the computer to control the injectors with no change. The coil wiring was pulled from the harness that came with the engine. I hooked it up like lextech described in the wiring file.

One thing to note, when I turned off cylinders 4 or 7 with efi live, the truck seemed to smooth out. When I turned off any other cylinder, the truck got worse.

[Chevydillan]

Need to verify the wire locations on the computer to the injectors and coils for those cylinders. Could you post up where you have them pinned in please.

[crzy8mnky]

From lextech's file:
a Purple wire to------C2-26 for Coil #1 Control
a Red wire to---------C2-27 for coil #4 Control
a Lt.Blu/Wht wire to--C2-28 for coil #6 Control
a Dk.Grn/Wht wire to--C2-29 for coil #7 Control
a Purple/Wht wire to--C2-66 for coil #8 control
a Red/Wht wire to-----C2-67 for coil #3 control
a Dk.Grn wire to------C2-68 for coil #5 control
a Lt.Blu wire to------C2-69 for coil #2 control
a Brown wire to C2-60 for Bank #1 Coils-Low Reference
a Brn/Wht wire to C2-61 for Bank #2 Coils-Low Reference

And for the injectors, I just swapped 2/3 and 4/7. There were no problems when I had done the 0411 swap.

I've verified these multiple times. I've also pulled the plug and held it against the block and there was spark. I don't know how to tell if it's hot enough though.

[Chevydillan]

In that file 4 & 7 are backwards I believe. I checked it against 2 other files and they are switched. Try that

[crzy8mnky]

One other thing I want to throw out there. When I pulled the vacuum line off the brake booster to the intake, there was a pressure difference, and it does seem like my brakes are harder than they use to be.

[crzy8mnky]

Right now I have C1-43 for injector 7 and C1-44 for injector 4.

Edit: I think you mean for the coils, since the solid colors control the odd banks and the stripes control the even banks. The labels are wrong, but the colors match the diagrams that I have.