Misfire on #4 cylinder

[QuadFor4]

I have an 05 quadcab with 63000 miles which has a random misfire on the #4 cylinder. It happens at random speeds and RPMs. The CEL keeps coming on, otherwise I would not know its happening. The truck seems to run flawlessly... No backfires, burps, hiccups or what ever else you may use to discribe a misfire.
I have put a new plug wire to that cylinder, switched plugs and fuel injectors between cylinders, ran seafoam threw the top end, fuel injector cleaner threw a tank of gas. Now here is another curve ball...if the truck sits for several hours or over night, it will not throw the trouble code until after I drive somewhere and shut it off. When I start it back up and start to drive after a few minutes to a couple hours later it will then throw the code.
The truck has venom coils and JTS wires (40,000 on them), champion plugs have 12,000 on them, tuned by Justin, headers and back are BB exhaust, JTS throttle body.
Any help or ideas will be appreciated.

 

[Stanimal]

Sounds like a possible bad coil. I think of that because after driving and shutting it off the coil will get heat soaked.

 

[QuadFor4]

Thought about the coil but quess who is not looking forward to pulling the intake again. I still have the OE coil so that is on the trouble shooting list.

 

[BAD SNAKE]

I would check the wiring harness for that injector. while its running bend the wiring to see if it misfires.

 

[ZCx]

just went through the exact same thing.

was throwin mis fire codes for #4 & #9 cyl. after she came up to temp.

them fancy Pulstar plugs were toast after bout 25K miles.

replaced all plugs & #4 still came back.

did the same checks as you. no joy.

for got the KISS rule. pulled #4 plug wire & no spark & no change in engine sound

pulled #6 wire & it looked like one of them plasma balls & engine ran real rough.

fresh set of coil packs & she be 100% again

 

[QuadFor4]

Thanks BadSnake. I had not tried that yet. Could not get it to misfire or throw a code by bending, moving, wiggling, or pulling either either end of those wires.

 

[QuadFor4]

2 votes for the coil pack. Keep the suggestions coming. I want to try all of the "easier" things before I spend an afternoon putting the factory coil back on.

 

[SANCHOBA]

worth a try....remove the neg. battery cable for a few minutes and reset ECM?

 

[ZCx]

glad its number 4 though.

was able to swap plug wires & check the plug for the coil pack

 

[QuadFor4]

I use my SCT to remove the code. It keeps coming back. That's how I have been trouble shooting. Change something, drive, reset, repeat.

I was pretty happy it was #4 as well. Check the simple stuff with the intake in place.

 

[QuadFor4]

Any other ideas?

 

[ZCx]

Any other ideas?

did ya try pullin the wire off of #4 to check for spark???

 

[VENOMOUS1 RACING]

Possible valve spring. They will trigger a misfire code. I know you said it runs no different, but its another possibility. Do as me the guys mentioned and you should be able to pinpoint the issue

 

[QuadFor4]

Yep, the misfire is very random and I think it's rare when it does happen. I have driven for 5 minutes before the CEL comes on and I have driven for nearly an hour before it comes on.
I do not notice the misfire. I can't hear or feel anything. Like I said, if the CEL didn't come on, I wouldn't know it was happening. I have owned this truck for 6 years and know exactly how it sounds and feels.

 

[QuadFor4]

Short of pulling the valve cover, is there any way to know if it's a spring?

 

[VENOMOUS1 RACING]

Short of pulling the valve cover, is there any way to know if it's a spring?

No sir and pulling cover is simple really. Doing a leak down test would show valve or spring issue as well. Valve cover is easy though

 

[ZCx]

Short of pulling the valve cover, is there any way to know if it's a spring?

bout it.

a compression/leak down test might be misleadin

 

[Yellow venom]

I had the same problem with those same plug wires! Haven't had a problem since I pulled them off and put a nice trouble free set of Adams wires on, your case sounds more like coils how your describing it.

 

[redice2]

had same issue at about 30k miles on my 05 qc when we pulled the coil pack the pin for number 4 was melted below it so i upgraded stinkers coil packs and his wires and havent had an issue since.

 

[BlackMamba50]

If you end up needing coil packs let me know, I have a spare set with low miles laying around.