Symptoms Testing

Test for the following conditions:
- The fuel system for the following:
  - Correct fuel pressure-Refer to FUEL SYSTEM DIAGNOSIS .
  - Fuel injectors that are leaking or improper operation-Refer to FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL or FUEL INJECTOR BALANCE TEST WITH TECH 2 .
  - Contaminated or a poor fuel quality condition-Refer to ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS (W/O SPECIAL TOOL) or ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS (W/ SPECIAL TOOL) .
- The ignition system for the following:
  - Spark plugs for incorrect heat range or an abnormal condition-Refer to SPARK PLUG INSPECTION .
  - For diagnosis of coolant or oil fouled spark plugs-Refer to LOSS OF COOLANT or OIL CONSUMPTION DIAGNOSIS .
  - 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 .
- The operation of the transmission torque converter clutch (TCC)-The scan tool should indicate an engine speed drop when the TCC is commanded ON.
- The operation of the A/C compressor
- Items that can cause an engine to run lean or rich-Refer to DTC P2178, P2180, P2188, OR P2190 .
- The crankshaft position (CKP) sensor for the correct resistance-The CKP sensor resistance may be out of range after a hot soak. The resistance should be between 700-1200 ohms.
- The engine for the following mechanical failures-Refer to SYMPTOMS - ENGINE MECHANICAL .
  - Excessive oil in the combustion chamber or leaking valve seals
  - Incorrect cylinder compression
  - Sticking or leaking valves
  - Worn camshaft lobes
  - Incorrect valve timing
  - 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.
- Knock sensor (KS) system for excessive spark retard activity-Refer to KNOCK SENSOR (KS) SYSTEM DESCRIPTION and DTC P0326, P0327, P0328, P0331, P0332, OR P0333 .
- 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 .
- 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 .
  - Proper engine coolant level-Refer to COOLING SYSTEM DRAINING AND FILLING (LY7 GE 47716 FILL) or COOLING SYSTEM DRAINING AND FILLING (LY7 STATIC FILL) .
If the above conditions do not address the symptom, refer to the ADDITIONAL SYMPTOMS TESTS .