Backfire, Cuts Out/Misses, Detonation/Spark Knock, Dieseling/Run-On, Hard Start, Hesitation/Sag/Stumble, Lack of Power/Sluggishness/Sponginess, Poor Fuel Economy, Rough, Unstable, or Incorrect Idle and Stalling, or Surges/Chuggles
- Test for the following conditions: The fuel system for the following: Correct fuel pressure-Refer to «Fuel System Diagnosis»(ref-318492-S08583324382009061700000) . Fuel injectors that are leaking or improper operation-Refer to «Fuel Injector Balance Test with Special Tool»(ref-318492-S20577957742009061700000) . Contaminated or a poor fuel quality condition The ignition system for the following: Spark plugs for incorrect heat range or an abnormal condition-Refer to «Spark Plug Replacement»(ref-318492-S19036855402009061700000) . For diagnosis of coolant or oil fouled spark plugs, refer to «Symptoms - Engine Mechanical»(ref-318523-S28437086382009061700000) . Wet down the secondary ignition system with water from a spray bottle-Wetting down the secondary ignition system may help locate damaged or deteriorated components. Look/listen for arcing or misfiring as the water is applied. Weak spark using the J 26792 Spark Tester-Refer to «Electronic Ignition (EI) System Diagnosis»(ref-318492-S07997576662009061700000) . The operation of the transmission torque converter clutch (TCC)-The scan tool should indicate an engine speed drop when the TCC is commanded ON. Refer to «Diagnostic System Check - Automatic Transmission»(ref-318524-S03748968092009061700000) . The operation of the A/C compressor Items that can cause an engine to run lean or rich-Refer to «DTC P0171 or P0172»(ref-318492-S30199540292009061700000) . The engine for the following mechanical failures-Refer to «Symptoms - Engine Mechanical»(ref-318523-S28437086382009061700000) : Excessive oil in the combustion chamber or leaking valve seals Incorrect cylinder compression Sticking or leaking valves Worn camshaft lobes Incorrect valve timing Worn rocker arms Broken valve springs Excessive carbon buildup in the combustion chambers-Clean the chambers with top engine cleaner. Follow the instructions on the can. Incorrect engine parts Vacuum hoses for splits or kinks-Verify that the routing and connections are as shown on the Vehicle Emission Control Information label. Refer to «Evaporative Emissions Hose Routing Diagram»(ref-318492-S26141482592009061700000) . Knock sensor (KS) system for excessive spark retard activity-Refer to «Knock Sensor Replacement»(ref-318492-S30959775782009061700000) and «DTC P0324, P0326, or P06B6»(ref-318492-S38052415272009061700000) . The exhaust system components for the following: Physical damage or possible internal failure The three-way catalytic converters for a restriction For more information, refer to «Symptoms - Engine Exhaust»(ref-318510-S27737454532009061700000) . Electromagnetic interference (EMI) on the reference circuit can cause a misfire condition. You can usually detect EMI with a scan tool by monitoring the engine speed parameter. A sudden increase in the engine speed parameter with little change in actual engine speed indicates that EMI is present. Inspect the high voltage components near the ignition control circuit if a condition exists. Inspect the positive crankcase ventilation (PCV) system and all connections for leaks or restrictions. Evaporative emission (EVAP) canister purge solenoid that is stuck open The engine cooling system for the following conditions: The thermostat is the correct heat range-Refer to «Thermostat Diagnosis»(ref-318497-S19692405822009061700000) . Proper engine coolant level-Refer to «Cooling System Draining and Filling»(ref-318497-S24200150142009061700000) .
- If the above conditions do not address the symptom, refer to the additional symptoms tests below.