Symptom Chart

Symptom	Possible Cause	Action
Engine cranks, but does not fire	Engine breather system disconnected/restricted Engine ignition system Fuel system Electronic engine controls	Ensure the engine breather system is free from restriction and is correctly installed Read DTCs and refer to DTC Index for engine ignition system tests For fuel system tests. Refer to Fuel Tank and Lines article. Read DTCs and refer to DTC Index for electronic engine controls. Refer to Electronic Engine Controls article.
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 coil failure(s)	For purge valve tests. Refer to Evaporative Emissions article. For fuel system tests. Refer to Fuel Tank and Lines article. For spark plug tests, Refer to Pinpoint Test A . For engine ignition coil circuit tests, check for DTCs and refer to 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	Check the engine coolant level and anti-freeze content. Refer to Specifications article. Ensure the battery is in a fully charged and serviceable condition Read DTCs and refer to DTC Index for electronic engine controls. Refer to Electronic Engine Controls article. For EGR system tests. Refer to Engine Emission Control article. For fuel system tests. Refer to Fuel Tank and Lines article. For purge valve tests. Refer to Evaporative Emissions article.
Difficult hot start	Injector leak Electronic engine controls Purge valve Fuel pump Engine ignition system EGR valve stuck open	Check for leaking injectors Read DTCs and refer to DTC Index for electronic engine controls. Refer to Electronic Engine Controls article. For purge valve tests. Refer to Evaporative Emissions article. For fuel system tests. Refer to Fuel Tank and Lines article. Read DTCs and refer to DTC Index for engine ignition system tests For EGR valve tests. Refer to Engine Emission Control article.
Difficult to start after hot soak (vehicle standing, engine off, after engine has reached operating temperature)	Injector leak Electronic engine controls Purge valve Fuel pump Engine ignition system EGR valve stuck open	Check for leaking injectors Read DTCs and refer to DTC Index for electronic engine control tests. Refer to Electronic Engine Controls article. For purge valve tests. Refer to Evaporative Emissions article. For fuel system tests. Refer to Evaporative Emissions article. Read DTCs and refer to DTC Index for engine ignition system tests For EGR valve tests. Refer to Engine Emission Control article.
Engine stalls soon after start	Breather system disconnected/restricted Electronic engine control Engine ignition system Air intake system restricted Air leakage Fuel lines	Ensure the engine breather system is free from restriction and is correctly installed Read DTCs and refer to DTC Index for electronic engine control. Refer to Electronic Engine Controls article. Read DTCs and refer to DTC Index for engine ignition system tests Check for blockage in air filter element and air intake system For fuel system tests. Refer to Fuel Tank and Lines article.
Engine hesitates/poor acceleration	Fuel pressure, pump and lines Injector leak Air leakage Electronic engine controls Engine ignition system EGR valve stuck open Transmission malfunction Restricted pedal travel (carpet, etc)	For fuel system tests. Refer to Fuel Tank and Lines article. Check for injector leak Check for leakage from air intake system Read DTCs and refer to DTC Index for electronic engine control tests. Refer to Electronic Engine Controls article. Read DTCs and refer to DTC Index for engine ignition system tests For EGR system tests. Refer to Engine Emission Control article. For transmission tests. Refer to Diagnostic Strategy article. Ensure accelerator pedal is free from restriction
Engine backfires	Fuel pump and lines Air leakage Electronic engine controls Engine ignition system Sticking Variable Camshaft Timing (VCT) hub	For fuel system tests. Refer to Fuel Tank and Lines article. Check for leakage in air intake system Read DTCs and refer to DTC Index for electronic engine controls. Refer to Electronic Engine Controls article. Read DTCs and refer to DTC Index for engine ignition system tests Read DTCs and refer to DTC Index for VCT tests. Refer to Electronic Engine Controls article.
Engine surges	Fuel pump and lines Electronic engine controls Engine ignition system	For fuel system tests. Refer to Fuel Tank and Lines article. Read DTCs and refer to DTC Index for electronic engine controls. Refer to Electronic Engine Controls article. Read DTCs and refer to DTC Index for engine ignition system tests
Engine detonates/knocks	Electronic engine controls Fuel pump and lines Air leakage Sticking VCT hub	Read DTCs and refer to DTC Index for electronic engine controls For fuel system tests. Refer to Fuel Tank and Lines article. Check for leakage from air intake system Read DTCs and refer to DTC Index for VCT tests. Refer to Electronic Engine Controls article.
No throttle response	Electronic engine controls	Read DTCs and refer to DTC Index for electronic engine control tests
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 Read DTCs and refer to DTC Index for electronic engine control tests. Refer to Electronic Engine Controls article. For transmission tests. Refer to Diagnostic Strategy article. Check for leakage from air intake system