Misfires

[NewToRamSteve]

Twice now after my truck has sat for a week while I was out of town, when I crank it, it runs rough, engine light comes on and code reads misfire. The second time it did it was on another cylinder and engine light started blinking and would not go over 35. I had it towed to dealer and they see the code and don’t think it is lifter or injector since on different cylinders, suspect fuel, they are going to keep it a week and try to duplicate it. 2019 1500 5.7 e torque longhorn limited. 42,000 miles,thanks in advance for ideas and sorry if this has already been posted, I couldn’t find it.


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[23RAM]

Twice now after my truck has sat for a week while I was out of town, when I crank it, it runs rough, engine light comes on and code reads misfire. The second time it did it was on another cylinder and engine light started blinking and would not go over 35. I had it towed to dealer and they see the code and don’t think it is lifter or injector since on different cylinders, suspect fuel, they are going to keep it a week and try to duplicate it.

I'm experiencing something similar - multiple cylinder misfires reported intermittently and it runs rough, CEL comes on (not flashing), but it will run up to at least 55 mph to get to the dealer 15 mins away. The dealer is trying to figure it out and thinks it might be a bad PCM. Once they read the codes and clear CEL, it'll start and run fine for a few days, then run rough, then next start it runs fine, then a couple starts later it runs rough again. They replaced cyl 5 coil pack when it was just on number 5, but now it happens on various cylinders. It's definitely not fuel for me, ran fine for half a tank then suddenly started to run rough while driving down the highway. I've since gone through another full tank from another station and same issue.

 

[NewToRamSteve]

Thank you, I will provide an update in a week when they crank it and see what they experience. Mine misfired on two completely different tanks of fuel also. I just hate it, really wanted this truck to be tough, but after a wiring harness getting water in it (covered under warranty-a known problem) and both exhaust manifolds cracking around 25k, I’m just bummed. Hopefully get this issue behind me and that’s it.


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[23RAM]

Thank you, I will provide an update in a week when they crank it and see what they experience. Mine misfired on two completely different tanks of fuel also. I just hate it, really wanted this truck to be tough, but after a wiring harness getting water in it (covered under warranty-a known problem) and both exhaust manifolds cracking around 25k, I’m just bummed. Hopefully get this issue behind me and that’s it.

I've barely hit 6k...hoping this gets resolved quickly as right now it's unreliable and I won't drive it out of town.

 

[theblet]

Has anyone checked fuel pressure?

 

[23RAM]

Has anyone checked fuel pressure?

I doubt it's fuel related as it's intermittent for me. I'd think if the fuel pump was weak, it would run rough all the time. It might be a cause for OP though.

 

[HSKR R/T]

Twice now after my truck has sat for a week while I was out of town, when I crank it, it runs rough, engine light comes on and code reads misfire. The second time it did it was on another cylinder and engine light started blinking and would not go over 35. I had it towed to dealer and they see the code and don’t think it is lifter or injector since on different cylinders, suspect fuel, they are going to keep it a week and try to duplicate it. 2019 1500 5.7 e torque longhorn limited. 42,000 miles,thanks in advance for ideas and sorry if this has already been posted, I couldn’t find it.


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I'd start by checking battery voltage, prior to cranking, after sitting.

And as mentioned, not so much s fuel pressure issue, but instead of hopping in and cranking it right away, after sitting, hit the start button, without foot on brake, and let it cycle through aux/run/off, then try starting it in second try. This will allow the fuel pump to prime the fuel rails twice. This will let you know if fuel is draining out of fuel rails while sitting.