Cummins ISB6.7 CM2350 (2013-17) Fault Code: 1656 PID: SPN: 1325 FMI: 31 Engine Misfire Cylinder 3- Condition Exists
Cummins ISB6.7 CM2350 (2013-17) Fault Code: 1656 PID: SPN: 1325 FMI: 31 Engine Misfire Cylinder 3- Condition Exists
Circuit Description
An algorithm in the ECM calibration monitors engine speed as each injector fires. If a cylinder(s) has high or low contribution to engine speed, the fault will become active. The intention of the fault is to assist in troubleshooting performance complaints such as engine misfire and low power.
Component Location
The ECM mounting location varies, depending on the engine model, and may be mounted either on or off the engine.
Conditions for Running the Diagnostics
This diagnostic runs continuously when the engine coolant temperature is greater than 71?C [160?F].
This diagnostic runs continuously when the engine is running.
Conditions for Setting the Fault Codes
1)The Engine Control Module (ECM) detected a cylinder 3 misfire.
Action Taken When the Fault Code is Active
2)The ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.
Exhaust Gas Recirculation (EGR) valve operation will be disabled.
Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.
Conditions for Clearing the Fault Code
1)To validate the repair, start the engine and let it idle for up to 5 minutes.
2)The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3)The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4)For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
5)The Reset All Faults command in INSITE? electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.
Shop Talk
If Fault Code 1656 is inactive in the ECM memory and there is no complaint such as ?low power? or ?engine misfire?, it is possible that an intermittent event, such as air entering the fuel system following a filter change caused the fault. Inactive counts of Fault Code 1656 should be disregarded unless other performance symptoms are present. The coolant temperature must be greater than 71?C [160?F] before this diagnostic will run.
Interview the customer and/or review the service history to determine if any recent repairs or maintenance events may have caused the fault.
Possible Causes:
1) Valve lash out of specification (compare actual valve lash to reset limits)
2) Cylinder malfunction (check for high blowby when the engine is loaded)
3) Valve train malfunction or valve held open (listen for intake valve ?chirping? noise in the intake)
4) Internal actuator harness pass-through connector damaged, corroded, or has a bad connection to injector or engine harness.
5) Extra, missing, or damaged sealing washer under an injector
6) Injector malfunctions (?swap? injectors to see if the problem ?follows? the indicated injector).
