Cummins running ruff

[ashdan2010]

2009 prostar cummins 871 680,000 miles. 2 questions. When I first crank the truck up engine fan cycles on and off is this normal or do I have a problem.
Second thing is when engine is cold it has a hesitation or miss. Rpm doesn't fluctuate, but you can definitely feel it and when she warms up it goes away. Any idea of what can be causing these problems. Thanks in advance for the help.

[gearhead]

Watch insite monitor the fan and see if ecm is doing it. This will narrow it down some. Do a cutout test while engine is cold this my find injector going bad

[Coco620]

Wow I did that to mine last night & #5 was louder than the rest...#5 going bad?

[Cuya]

(02-21-2016 )Coco620 Wrote:  Wow I did that to mine last night & #5 was louder than the rest...#5 going bad?

did you do an injector leak test first?

[Coco620]

(02-22-2016 )Cuya Wrote:  

(02-21-2016 )Coco620 Wrote:  Wow I did that to mine last night & #5 was louder than the rest...#5 going bad?

did you do an injector leak test first?

I didn't do that but just watched the video
Thanks again Rawze

[Fordmandan87]

The crankshaft dampener hardens around 500k and you start feeling more engine vibration as a result. Not saying that's the cause but it could be making it more noticeable.

[Isx Lover]

(02-24-2016 )Fordmandan87 Wrote:  The crankshaft dampener hardens around 500k and you start feeling more engine vibration as a result. Not saying that's the cause but it could be making it more noticeable.

Here is a picture of my damper with 1020000 miles on it. I don't know what they are supposed to look like but here's mine. The black stuff has consistency of tar.

[RTRUCKING48]

(02-21-2016 )ashdan2010 Wrote:  2009 prostar cummins 871 680,000 miles. 2 questions. When I first crank the truck up engine fan cycles on and off is this normal or do I have a problem.
Second thing is when engine is cold it has a hesitation or miss. Rpm doesn't fluctuate, but you can definitely feel it and when she warms up it goes away. Any idea of what can be causing these problems. Thanks in advance for the help.

I also have a 09 prostar with the 871cummins with 677,000 miles and its doing the same thing on the miss and on the fan I notice that when the air pressure is below 90psi fan comes on once it builds more than 90psi cuts off the fan

[the missing link]

2 things with the fan
1 the fan clutch is engaged with no air presser , until you hit 90 psi it will not put air to the fan to shut it off. When air is sent to the fan it kicks out the clutch
2 your a/c will turn your fan on / off ,when you start you truck or stop. If you shut off your heater controls this should tell if it is you a/c . Your heater will also use your a/ c to take humidly out of the air
At least on my trucks this is how it works

Hope this helps.