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03 Cummins rough idle (HELP)

Discussion in 'Ram Trucks' started by diezelfreak, Jan 6, 2015.

  1. diezelfreak

    diezelfreak Member
    Messages: 36

    My truck started to run like cap the other day at a idle. Then I let it idle and let it come up on high idle (1000rpm) it smooths right out dumped a thing of power service in drove it to town got a fuel filter drove home and still missing at a low idle. I changed the fuel filter left the filter lid loose turned the key on to make sure the lift pump was pushing fuel and it is. Fired it up and it is still missing... And there is no check engine light and no pending codes... Had the ECM rebuilt about 20k miles ago. Truck currently has 248k miles. Any help would be greatly appreciated. Thank you in advance. I have a video just gotta figure out how to get it on you tube to put here.
  2. Randall Ave

    Randall Ave PlowSite Veteran
    Messages: 3,587

    You have to connect to a scanner that can run tests, then run injector cut outs. this should isolate the missing cylinder. Not everything will cause a check engine light.
  3. edgeair

    edgeair Senior Member
    Messages: 597

    My 04 did that at and it was a bad injector.
  4. diezelfreak

    diezelfreak Member
    Messages: 36

    Started getting excessive blow by. So I tore the motor down (luckily with the 3rd Gens you pull the oil pan without pulling the motor) found #6 piston had both compression rings broke and a good size piece of the piston broke between the 2nd compression and oiler ring....the good news it's didn't leave a single mark on the cylinder wall. The factory cross hatching is still very visible in all of cylinders!