N14 celect plus loping at idle, and won’t accelerate

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by JRehms, Aug 8, 2022.

  1. JRehms

    JRehms Bobtail Member

    4
    1
    Aug 8, 2022
    0
    I have a 2000 Peterbilt 379 with n14 celect plus. When u crank it , it barely idles (around 400 rpm) and is loping pretty bad, and it won’t accelerate unless u spray with ether and get rpm’s up then it runs fairly decent but won’t rev past 1700 rpm’s . Soon as rpm’s get below 1000 it starts loping again and won’t accelerate. It throws a 343 engine code at random times and goes back out. I’ve replaced timing sensor, fuel solenoid, engine wiring harness,and Ecm. I’ve removed belts on alternator and checked all grounds and hots. I have 12.2 volts at fuel solenoid, I’ve got a lot of time and money in this fix and haven’t figured it out and need a little help. Any help would be appreciated .
     
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. Judge

    Judge Road Train Member

    7,483
    45,153
    Mar 19, 2014
    Newport, Ar
    0
    I know some are gonna say, “Judge, You CraZy.”

    I’d check electrical connections.
    replace all battery jumper cables. replace both hot & ground main cables. corrosion gets under the coating where you cannot see it.

    code shows…
    Defective alternator occasionally cause Fault Code 343 . Run the engine with the alternator belt off; if the fault code becomes inactive, replace the alternator . Intermittent battery shorts to ground can cause the fault.

    I know you said you checked some of this along with new ECM and harness, but here it goes,

    Loose engine or chassis ground connections can cause Fault Code 343 to be logged, as well as complaints of an intermittent stumble. Pay special attention to the negative starter post connection.
    * Moisture in the ECM connectors can also cause the ECM to log Fault Code 343. Refer to Service Parts Topic 95T19-12A for details on water intrusion.
    * A damaged EPS can cause the ECM to log Fault Code 343 and possibly Fault Code 121 and Fault Code 115.
    * Defective alternators occasionally cause FC 343. Run the engine with the alternator belt off; if the fault code becomes inactive, replace the alternator.
    * Intermittent battery shorts to ground may cause the fault.
    * Intermittent shorts to ground in these circuits: injector solenoids, injector harnesses, fan clutch solenoids, fan clutch wiring, engine brake solenoids, engine brake wiring, OEM installed engine speed sensors, flywheel housing and associated wiring, datalink wiring, and fuel shutoff solenoid or wiring may cause intermittent Fault Code 343.
    * To determine if conducted electrical noise through the grounds is causing the Fault Code 343, unbolt the ECM, and move it away from the engine block so that it is isolated from the engine block ground. If the fault is not duplicated, troubleshoot for the source of the electrical noise.

    The * From Cummins site.
     
  4. JRehms

    JRehms Bobtail Member

    4
    1
    Aug 8, 2022
    0
    I haven’t replaced the wires at batteries but I have tested them but it is worth a shot
     
  5. JRehms

    JRehms Bobtail Member

    4
    1
    Aug 8, 2022
    0
    All connections are good and wires are good , jumpers are good ,batteries are good and all fuses are good
     
  6. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

    1,697
    1,620
    Jun 14, 2009
    romulus,mi
    0
    Injector drivers in ECM bad. Reminds me of the good ole days.....
     
    pup, Heavyd and spsauerland Thank this.
  7. JRehms

    JRehms Bobtail Member

    4
    1
    Aug 8, 2022
    0
    Can the cam be walking away from timing sensor and not reading correctly? If so how can I check it?
     
    baha Thanks this.
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  • Draft saved Draft deleted