| Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. |
| 08-03-2025, (Subject: Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. ) Post: #1 | |||
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 Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. Greetings, I was working on a 2014 Cummins M2 that needed injectors (too much return) . I swapped out the injectors and the truck ran fine until I put the injector codes into the ECM. When I did that it started running rough and misfiring. Now the engine surges up and down and won't rev up. The fuel rail pressure and commanded pressure are about 11000 psi. The press relief valve is ok, the injector return is within limits. I did notice the fuel rail pressure drops pretty fast upon engine shut down, and the only active code is turbo speed sensor. I had another HP pump head and installed it but no change. I will look at fuel aeration tomorrow since it acts like there is air in the system. This problem is keeping me up at night. Can anyone shed some lite on this issue. Thanks | |||
| 08-04-2025, (Subject: Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. ) Post: #2 | |||
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RE: Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. (08-03-2025 )wrench buster Wrote: Greetings, I was working on a 2014 Cummins M2 that needed injectors (too much return) . I swapped out the injectors and the truck ran fine until I put the injector codes into the ECM. When I did that it started running rough and misfiring. Now the engine surges up and down and won't rev up. The fuel rail pressure and commanded pressure are about 11000 psi. The press relief valve is ok, the injector return is within limits. I did notice the fuel rail pressure drops pretty fast upon engine shut down, and the only active code is turbo speed sensor. I had another HP pump head and installed it but no change. I will look at fuel aeration tomorrow since it acts like there is air in the system. This problem is keeping me up at night. Can anyone shed some lite on this issue. will it pass a fuel rail leak test just like this video shows??. ref: https://rawze.com/forums/showthread.php?...3#pid75483 if not, then that is the place to start. User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!. | |||
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| 08-07-2025, (Subject: Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. ) Post: #3 | |||
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| RE: Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. Hello, I ran a system pressure test today and it didn't hold within specs. I found inj # 1 was leaking bad when I turned the engine off. I thought alright I found the problem, however that would have been too easy. I replaced # 1 with a Cummins re-man and the rail pressure held within specs. I ran a injector return test under hi pressure and it was within specs. (80 ML) in 1 minute. I am really stumped on this one because it still idles rough and misfires upon acceleration. The HP pump produces 29,000 psi so I don't believe that's the problem. I am leaning towards defective injectors or an ECM issue. If someone can help me narrow this down I would very much appreciate your help. I have no codes, if it was an electrical issue I believe it would throw a code.It feels liike ALL cylinders are misfiring upon acceleration not just 1. When I do the cylinder cut out it seems like very little RPM loss on ea. cyl. Regards Wrench Buster | |||
| 08-07-2025, (Subject: Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. ) Post: #4 | |||
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| RE: Engine miss Hey there, The pressure is holding fine after replacing a leaky # 1 Cyl. inj. Also the HP pump builds and hold 29, 000 psi no problem and holds. I believe you mentioned a ECM issue may be the problem, can you elaborate on that? Thanks | |||
| 08-07-2025, (Subject: Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. ) Post: #5 | |||
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| RE: Engine miss Has there been something done to the ecm programming wise? Something mandate'd or more power added? | |||
| 08-07-2025, (Subject: Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. ) Post: #6 | |||
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| RE: Engine miss | |||
| 08-08-2025, (Subject: Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. ) Post: #7 | |||
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RE: Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. (08-07-2025 )wrench buster Wrote: Hello, I ran a system pressure test today and it didn't hold within specs. I found inj # 1 was leaking bad when I turned the engine off. I thought alright I found the problem, however that would have been too easy. I replaced # 1 with a Cummins re-man and the rail pressure held within specs. I ran a injector return test under hi pressure and it was within specs. (80 ML) in 1 minute. I am really stumped on this one because it still idles rough and misfires upon acceleration. The HP pump produces 29,000 psi so I don't believe that's the problem. I am leaning towards defective injectors or an ECM issue. If someone can help me narrow this down I would very much appreciate your help. I have no codes, if it was an electrical issue I believe it would throw a code.It feels liike ALL cylinders are misfiring upon acceleration not just 1. When I do the cylinder cut out it seems like very little RPM loss on ea. cyl. Is this engine de-mandated (deleted)?.. If so then the program needs to be copied out and sent to me for a review of what someone did in there. - For all anyone knows, it could be throwing 50 faults and some idiot suppressed them all, making it not show anything wrong. Also.. you might want to do this .. to ensure its not something external causing it to run like crap... ref: https://rawze.com/forums/showthread.php?...6#pid80656 ... it will also run like crap if the crank or cam position sensors are not reading correctly.. and/or if the overhead cam has slipped,.. or if the tone ring on the crankshaft is loose. User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!. | |||
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| 08-08-2025, (Subject: Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. ) Post: #8 | |||
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| RE: Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. So it went to hell after you put in the injector codes? The Internationals I normally work with don't use injector codes, so I know little about this. BUT if it won't run on the correct codes, maybe somebody HAS messed with the programming. Any chance of putting the origional codes back in and seeing what happens? Whose injectors? Quality is all over the board on injectors in general. I wouldn't trust anything except Cummins or maybe Bosch. | |||
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| 08-09-2025, (Subject: Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. ) Post: #9 | |||
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| RE: Freightliner M2 with Cummins ISC 8.3 uneven idle, won't rev. The injectors were from a diesel injection shop locally. I will try your suggestion of installing the original injector codes back in today and see what happens. Thanks for your suggestion | |||
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