Help! Unballance Ltft

[glenn-ho]

Well started with a P0305 that I found to be a bent valve #5 cyl exhaust. Before finding #5cyl down to 145lbs compression I replace the spark plugs (Delco), wires (Bosch), cap (Accel), and rotor (Accel). Pulled both heads and sent out to repair. Replaced the valve springs and seals along with 3 exhaust valves. Started truck up and then had a P0300 random misfire. Found the spider bad and replaced with a delphi updated injector set up. Fired right up and runs perfect cold but after warm up at idle in gear it stumbles and appears to have a misfire. Does not throw any codes. Replaced the MAP but no help. Replaced the cam sensor no help. Did a crankshaft relearn no help.

 

While I was waiting for the heads to come back I cleaned the upper and lower intake, IAC, and the EGR.

 

The O2 sensors where replaced with A/C delco about 30,000 miles ago and the cat was replaced with a complete magnaflow with y pipe at the same time.

 

 

At idle in neutral the B1 LTFT is 5.4 and the B2 LTFT is 7.0?

 

I have a hypertech tune installed would this stop the readiness with the updated injectors?

 

Spark advance 19.2

Idle 650

Map 9.7

maf .777

 

 

1998 Chevrolet K1500 4.3l

[glenn-ho]

Well found the problem. Truck would run fine at idle in neutral. Would run fine at idle in gear cold. At idle at normal operating temp it would miss and not set a CEL. Not all the time but pretty constant when truck was up to operating temp in gear at idle. Give is gas and it would run perfect all the time no matter what. Got my thermal temp gun out and read temp at each cylinders exhaust manifold port and #3 cylinder was colder by a 100 degree. This brought my attention to that cylinder and when it missed you could hear a faint snap. Had my wife sit in the truck and apply the brake while I listened to it at idle in gear. Sprayed water which would make it worse but could not see any arcing. Pulled the wire off and read it with an ohm meter and it read fine. Figured it was a plug and replaced it with a new plug. Same thing miss at idle in gear. Replaced the wire and now it runs prefect. Checked wire again with an ohm meter while I wiggled the wire and made no difference read fine. I started bending the wire looking for a bad spot and then I looked at the spark plug boot and found a very small cut no bigger than a 1/8 of an inch right at the connector for the plug. That explains why I could not see the arcing since it was next to the heat shield inside where you cannot see. What the F>>>>>!!!