Symptom Chart

Symptom	Possible Causes	Action
Engine cranks, but does not fire	Engine breather system disconnected/restricted Ignition system Fuel system Electronic engine control	Ensure the engine breather system is free from restriction and is correctly installed. Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Engine cranks and fires, but will not start	Evaporative emissions purge valve Fuel pump Spark plugs HT short to ground (tracking) check rubber boots for cracks/damage Ignition system	Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Difficult cold start	Engine coolant level/anti-freeze content Battery Electronic engine controls Exhaust Gas Recirculation (EGR) valve stuck open Fuel pump Purge valve	Refer to the relevant section of the workshop manual and test the engine coolant level and condition Refer to the relevant section of the workshop manual and test the battery Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Difficult hot start	Injector leak Electronic engine control Purge valve Fuel pump Ignition system EGR valve stuck open	Check for injector leak, install new injector as required Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Difficult to start after hot soak (vehicle standing, engine off, after engine has reached operating temperature)	Injector leak Electronic engine control Purge valve Fuel pump Ignition system EGR valve stuck open	Check for injector leak, install new injector as required Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Engine stalls soon after start	Breather system disconnected/restricted ECM relay Electronic engine control Ignition system Air intake system restricted Air leakage Fuel lines	Ensure the engine breather system is free from restriction and is correctly installed Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index Check for blockage in air filter and air intake system Check for air leakage in air intake system
Engine hesitates/poor acceleration	Fuel pressure, fuel pump, fuel lines Injector leak Air leakage Electronic engine control Throttle motor Restricted accelerator pedal travel (carpet, etc) Ignition system Exhaust Gas Recirculation (EGR) valve stuck open Transmission malfunction	Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index Check for injector leak, install new injector as necessary Check for air leakage in air intake system Ensure accelerator pedal is free from restriction Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) and Transmission Control Module (TCM) for related DTCs and refer to the relevant DTC index
Engine backfires	Fuel pump/lines Air leakage Electronic engine controls Ignition system Sticking variable camshaft timing (VCT) hub	Check for fuel system failures Check for air leakage in intake air system Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Engine surges	Fuel pump/lines Electronic engine controls Throttle motor Ignition system	Check for fuel system failures. Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Engine detonates/knocks	Fuel pump/lines Air leakage Electronic engine controls Sticking VCT hub	Check for fuel system failures Check for air leakage in intake air system Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
No throttle response	Electronic engine controls Throttle motor	Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM) for related DTCs and refer to the relevant DTC index
Poor throttle response	Breather system disconnected/restricted Electronic engine control Transmission malfunction Traction control event Air leakage	Ensure the engine breather system is free from restriction and is correctly installed Using the manufacturer approved diagnostic system, check the Engine Control Module (ECM), Transmission Control Module (TCM), and Anti-lock Brake System control module (ABS) for related DTCs and refer to the relevant DTC index Check for air leakage in intake air system