Peterbilt 379 Missing and shaky idle

Discussion in 'Peterbilt Forum' started by Easton379, Mar 22, 2024.

  1. Easton379

    Easton379 Bobtail Member

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    Mar 22, 2024
    Colorado Springs Colorado
    0
    Hello. I am new to this forum and I apologize if I posted in the wrong section. I usually read a lot on here but I can’t seem to find anyone who has the same problem. I have a 2007 Peterbilt 379 with a c15 Acert nxs and I have a shake at idle and a miss at around 1300+ rpm. The miss sounds like a fuel knock and it’s really loud and bad when I’m loaded but softer and quieter when I’m empty. Fuel pressure is good, it doesn’t smoke, no code, and passes a cut out test. Has minimal blow by and uses about a gallon of oil between 10k oil changes and doesn’t use any coolant. Does anyone have any ideas? I’m at a loss and new in the business so funds are low to send it in and have it really torn into
     
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  3. Diesel Dave

    Diesel Dave Last Few of the OUTLAWS

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    Did you do and individual injector cut out test ?
     
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  4. Easton379

    Easton379 Bobtail Member

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    Mar 22, 2024
    Colorado Springs Colorado
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    Yes we did and no real change between cylinders
     
  5. Diesel Dave

    Diesel Dave Last Few of the OUTLAWS

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    I asked cuz when I had my 5Ek series, I had a bad injector that didn’t show in the Cat ET. The solenoid was fine I guess but the mechanicals of the injector was bad. It missed when I did the individual cut out test. That’s why I asked.
     
  6. Easton379

    Easton379 Bobtail Member

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    Mar 22, 2024
    Colorado Springs Colorado
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    My mechanic wants to pull all of the injectors and check the O-rings use a camera to check the cylinders and do a compression test. Have you used aftermarket injectors before? I was thinking about buying a set of six and having him put them in because cat wants 860 each
     
  7. Diesel Dave

    Diesel Dave Last Few of the OUTLAWS

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    I only replaced one injector the time I had my 379. Bought it at peterbilt. Cat was more expensive. Any work that I had done to my Cat was all Genuine Cat parts. Others in this forum can elaborate on aftermarket parts.
     
  8. Easton379

    Easton379 Bobtail Member

    7
    3
    Mar 22, 2024
    Colorado Springs Colorado
    0
    Ok thank you. I’m going to try new injectors hopefully that fixes it
     
  9. Last Call

    Last Call Road Train Member

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    Mar 15, 2021
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    Listen to what @Diesel Dave says … Do NOT buy reman injectors find your bad one and go through your Peterbilt dealer and buy a Cat injector you will be money ahead
     
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  10. Troy_

    Troy_ Road Train Member

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    Dec 13, 2017
    Roma, Alberta.
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    Engine all original? I had a bad reman head from a platinum in frame, injector seats in the head weren't properly machined and had the same symptoms. Didn't start doing it until a couple years after the rebuild. Cat stood behind it and warrantied everything.
     
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  11. Easton379

    Easton379 Bobtail Member

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    Mar 22, 2024
    Colorado Springs Colorado
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    I bought the truck 8 months ago with 400k on an inframe. How did you figure out that was your problem?
     
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