rough idle

01stroked · Nov 17, 2011

My friend just bought a 95 powerstroke and it runs great but has a rough ide or miss. When in the throtle it runs fine.. after you run it for a hour or so the rough idlegets worse.. ne ideas?

Tom S · Nov 17, 2011

Is is possibly only running on 7 cylinders?

01stroked · Nov 18, 2011

Well he got his hands on a scan tool and it showed all injectors are workin properly so I would think it would be running on al cylinders but I forgot to tell him to check icp couold that be somthing

94.5stroker · Nov 18, 2011

is it a Zf5?

01stroked · Nov 18, 2011

Yes its the 5 spd

Patrick Feeley · Nov 18, 2011

Have him check for a dual mass flywheel (DMFW). If it still has it, remove the inspection cover and check to see that the flywheel still has all the damepening springs and retainers intact (DMFW's have the springs in the flywheel rather than the clutch disk hub like normal one-piece flywheels). Check the rotational play between the two masses (try to rotate them against each other). Measure the play at the rim and it should not be more than 5/8". Bad DMFW's can mimic a miss and cause a rough idle. Cheers!

01stroked · Nov 19, 2011

alrght thankyou i will tell him

94.5stroker · Nov 21, 2011

Patrick Feeley said:
Have him check for a dual mass flywheel (DMFW). If it still has it, remove the inspection cover and check to see that the flywheel still has all the damepening springs and retainers intact (DMFW's have the springs in the flywheel rather than the clutch disk hub like normal one-piece flywheels). Check the rotational play between the two masses (try to rotate them against each other). Measure the play at the rim and it should not be more than 5/8". Bad DMFW's can mimic a miss and cause a rough idle. Cheers!

Yeah I was thinkin that...... another thing is, it could be something in the fuel....... I am having the same problem and every time I clean the fpr screen in the fuel bowl, there is some nasty black stuff....... I'm thinkin mine is algae but I'm not sure. Seems to clean up the idle pretty much when I clean the screen, then it eventually goes back to the slight rise and fall. I put some FuelSaver antimicrobial fuel additive from John Deere in it(cause my dad works there and he grabbed it for me to try) but after a couple tanks from putting it in it's still doin it so idk. I would check the fuel bowl/the screen in the fpr and see if you have crap in your fuel in addition to checking the flywheel.