Air into the fuel system? I'm confused: fuel pressure is greater than ambiant air pressure.

 

Hi all,

Thanks for the suggestions.

Learned a lot looking at the truck and this engine... it has the most bizarre coil design I've ever seen where coil #1 fires cyl 1 and 2, coil #2 fires cyl 3 and 4 etc...

So here's what I discovered... on Cyl #3 and 5 you could see spark between the coil and head before it hit the plug so it was an obvious misfire... took the coils off and there had been an obvious recent tune-up with new plugs (ngk copper yuck) but new wires running to the passenger side (that was helpful) so I put some dielectric grease on all coils and wires and reassembled and it fixed cyl # 3 but #5 still showed spark. Moved it over to cyl #1 and sure enough the misfire moved to cyl #1. Replaced the coil and all CEL's cleared and didn't come back.

Cliff Notes: Tune up without di-electric grease and a bad coil. Assume all "other" codes were symptoms of multi-cylinder misfire.

 

Good job!

Re: NGK copper, the consensus here seems to be that these engines run best with copper plugs.

 

I run one of 2 brands in everything NGK or Autolite and never have a problem

 

The "coil design" is actually not coil design. You are referring to "waste spark"...which has been around for 25 years. Before I started using a stand alone ECU in the race car, I had waste spark with the factory ECU...since 1991. I made a tad over 500whp on waste spark...and several guys over 800whp still run waste spark. In fact, a guy down the street just made 735whp on his street car...with the factory ecu and waste spark...with only 2.3L of displacement, E85, boost, no bottle.