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*ENGINE SPEED SURGES LOW OR HIGH IDLE Possible Causes POSSIBLE CAUSES Diagnostic Test 1. POSSIBLE CAUSES This is a list of possible causes: Check for any TSBs for ECM calibration updates that my apply. Fuel level low. Fuel filter plugged. Poor quality or improper grade of fuel. Fuel tank venting. Low fuel pressure. Air in fuel system Fuel Lift Pump malfunctioning. Fuel Inlet restriction. Fuel line kinked or restricted. Fuel return passage or fuel return line kinked or restricted. Injectors are incorrect. Injector shim thickness is incorrect. Injector malfunction. Fuel connector leaking fuel. High pressure Fuel pump. Accelerator pedal is restricted or out of calibration. Vibration damper is damaged. Crankshaft position sensor (CKP) or Camshaft position sensor (CMP) and/or circuit malfunction. Vehicle Speed sensor (VSS) and/or circuit malfunction. Incorrect Transmission Clutch operation. Check vehicle brakes for dragging, transmission malfunction, cooling fan operation cycle time and engine driven Check for proper turbocharger, turbo charger wheel clearance is out of specifications, waste gate for correct oper- Bus communication problems. Moisture in harness connectors or corroded terminals. Internal engine damage. Electronic noise. Idling with excessive load. Clutch is malfunctioning or incorrect. Speed indicator ring Injector circuit View repair. Repair Repair as necessary. Refer to Service Information for the related symptom(s). Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC- 9 - 1474 ENGINE - ELECTRICAL DIAGNOSTICS - DIESEL DR/DH |