Well i have been having a serious problem with misfires on my 2002 ram 1500 5.9 4x4. It started as a #1 and #8. I changed the spark plugs. #8 spark plug tip was broken and covered in oil. Used a magnet to retrieve piece. Afterwards though #1 went away, but #8 stayed there. Changed the wires on all, still stayed there. So i swapped the #4 and #8 fuel injectors #8 still misfired. I pulled #8 plug back out and it was covered in oil again. So i sprayed carb cleaner in cylinder and blew it out with air hose, then replaced plug. Still nothing changed. I tried checking the intake gasket with carb cleaner, and i found nothing. Really need help any suggestions????

 

Now #1 is misfiring again even after changing plugs again... really frustrated and dont know what to do

 

For future reference:
https://dodgeforum.com/forum/dodge-r...s-section.html

I will move this to the 2nd Gen Ram section (1994-2001), because even though you have a 3rd Gen Ram body, you have the drivetrain of a 2nd Gen.

 

Sounds like a blown plenum and maybe some combustion chamber failure on no. 8.

 

+1 to the blown plenum gasket. Probably have a fouled 02 sensor and plugged catatlytic converter as a result, as well.

 

Check plenum (read sticky here) and do a compression and leakdown test.

 

Same issue I had. If you didnt fix the plenum, fix it. If your plemum has been bad for awhile might as well get a new converter or gut it out while your at it, and change the O2 sensor while your at it or the misfire will come back.

 

Sorry, no internet for a while... well did compression test. Cylinder 8wouldn't build any kind of compression. So i did what anyone would do. I tore the motor apart. Turns out the piston was broken all the way down on one side. So i changed the piston while the heads were in the machine shop. Then got a call that both heads were slightly cracked, so f*** it put new heads too.. basically every gasket on the motor, including the plenum. Just finished today, no misfire or any other problems so far. Thanks for all the help. BTW pulling the oil pan in an 02 1500 5.9 4x4 is a huge pain in the ***.

 

good result, (other than your wallet). the motor will outlast the rest of the truck...

i knew the 02 2500 was still a 5.9 but i didn't know the 1500 still had a 5.9, i thought they all went to the 4.7