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-   -   Cylinder 5 misfire. Tried everything I can think of! (https://www.performancetrucks.net/forums/tuning-diagnostics-electronics-wiring-161/cylinder-5-misfire-tried-everything-i-can-think-550502/)

Jake75 10-04-2017 08:17 PM

Cylinder 5 misfire. Tried everything I can think of!
 
took the truck to the dyno tuner noticed a cylinder 5 misfire. I swapped coil and injector on the dyno. Still had cylinder 5 misfire. Changed plug wire and plug. Still cylinder 5 misfire. Came home traced all the injector and coils back to the pcm everything was good. Did a compression test all the cylinders matched up. Today I pulled the head valves and lifters were fine. Cylinder walls look good. The way I have been testing it was on the hptuner scanner I turn off an individual injector and you can hear the engine make a noticeable change and runs rough. When I turn off cylinder 5 there's no change at all. I pulled the rail off the intake and verified the injector is firing...it is. Now idk what else to check.

trxmxzx 10-04-2017 08:19 PM

Plug carbon tracking? Cracked?

Jake75 10-04-2017 08:50 PM


Originally Posted by trxmxzx (Post 5420782)
Plug carbon tracking? Cracked?

Plug is clean. You can see on the strap that it has spark to the strap

trxmxzx 10-04-2017 09:00 PM


Originally Posted by Jake75 (Post 5420789)
Plug is clean. You can see on the strap that it has spark to the strap

https://cimg9.ibsrv.net/gimg/www.per...bd8d733802.png

Jake75 10-04-2017 09:25 PM

I also replaced the plug and plug wire

Jake75 10-05-2017 08:40 PM

Took the head to the shop today. They said it seemed like the exhaust valve wasn't sealing so I had them cut and clean all the valve seats

ZO6Ted 10-06-2017 01:13 PM

Im assuming you used known good parts from other cylinders when you switched and then switched back assuring they werent damaged in the process with no change. I've gotten bad new parts before. Go through it again to verify one more time...sucks.

Jake75 10-06-2017 05:47 PM


Originally Posted by ZO6Ted (Post 5420993)
Im assuming you used known good parts from other cylinders when you switched and then switched back assuring they werent damaged in the process with no change. I've gotten bad new parts before. Go through it again to verify one more time...sucks.

Yup I took the known good coil and injector from 3 took the suspect injector and coil from 5 and put them on 3. With the known good injector and coil on 5 cylinder 5 still misfired. Cylinder 3 ran fine with the suspect parts from cylinder 5.

madmann26 10-08-2017 12:29 PM

Have you tried SeaFoam'ing it yet?

I'd get some DeepCreep and spray directly into the cylinder, let it sit, fire it up, rev it a few times (it's going to smoke like hell) and then SeaFoam the regular way.


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