N14 cummins miss at idle - Diesel Truck Forum - TheDieselGarage.com
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post #1 of 2 (permalink) Old 02-21-2020, 08:26 PM Thread Starter
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N14 cummins miss at idle

I am chasing a miss at idle again with my cummins n14. It is in a 98 fld120 425hp It will miss and sound like the motor is kind of loping after it warms up for a few minutes. It is pulling real good but sounds bad at idle. I have replaced the ecm, injector harness, and 5 injectors in the last 3 months. The 6th injector is 1 year old. When I unplug each injector, they all seem to make a difference in idle but I know that this is not the correct method since the Insite program isolates the amount of fuel going to each injector when doing the cutout test. I think that maybe I have an injector that is over fueling possible and causing the ecm to compensate fuel supply to other injectors but I dont know how to isolate this . If I set the idle up to 1000rpm it will run a little rough for about 3-4 seconds and then clear up and run smooth. I have been reading this forum for years and finding solutions from everyone's input but this is my first thread because I cant find where someone else has had this particular issue. Thanks in advance for any help
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post #2 of 2 (permalink) Old 03-15-2020, 10:56 AM
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Have you made basic fuel checks like air in fuel, fuel restriction and rail pressure? Were the injectors you put in new or recon? Recon's don't exactly have a stellar reputation. Maybe try checking exhaust temps to isolate a cylinder. You're not wrong in suspecting one injector could be over fueling at idle. You didn't say if you've tried a cylinder balance test with insite. This can be a difficult problem to find.
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