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Discussion Starter #1
my truck is missing but only if you stop at a stop light u can barley feel it every one says its the pump but it has a brand new one straight from cummins post ideas:splat
 

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sounds like the pump to me too. On my truck that was happening from time to time and when I put the FASS on it all went away. Fresh filter might be a good idea, I don't know when you put your last one in but they can get clogged quickly. maybe blocks or air getting in some how. Are you showing any trouble codes?
Sean
 
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Are you sure it is a miss and not a lopey idle? How old and how many miles is brande new? Is your lift pump working? I agree on the fuel filter, never hurts to change it, even if you just did. Check for codes and see if you have any. The pump is ually one of the few things it can be after fuel filter and lift pump.
 

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My truck also does this. I heard that it was the iat sensor that was bad. Its a 20 dollar sensor at a dealership. I havent tried it but i heard that it fixes it also.
 
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The IAT sensor should do nothing more than tell the ECM when to turn the grids on and off. Maybe it does, but I can not see where it would have any effect on the idle of the truck.
 

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I - Intake
A - Air
T - Temp.

No effect on the idle, just tells the ECM what the intake air temp is.

DB
 
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Ok after reading a little about the sensor it appears to have more functions than just telling the ECM temperatures for the grids. On the 24v motors it also provides temperatures in the from of Ohms to help the ECM adjust timing and fueling. Even if bad, it should not make a stumble in your idle. I would think it is more so one one cylinder on the motor or one plunger/barrell in the VP44. It should be more consistent and be rough idle all the time if all or multiple cylinders were mis-firing.

Also if you have any type of timing box such as an Edge EZ on the truck, then the timing is going to be bumped and override what the IAT sensor is telling the ECM anyways.

Anyone else have any ideas?
 

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Discussion Starter #9
the pump proly has about 1,000 miles on it maybe / runs good driving but just at idle
 

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well cummins folks are human too, if indeed its not the pump it could be an injector plugged or one that has a bad spray pattern giving you a slight shake (not that the 24 valve dont shake enough). thats all i can think of off hand.
 
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