2010 Cadillac CTS Sedan AWD V6-3.6L Page 1297
1. Engine idling at the normal operating temperature.
瀚慖f there is an abnormal engine noise, refer to Symptoms - Engine Mechanical (See: Engine, Cooling and Exhaust/Engine/Testing and
Inspection/Symptom Related Diagnostic Procedures/Symptoms - Engine Mechanical).
2. Verify that no other DTCs are set.
瀚慖f a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code Descriptions/Diagnostic Trouble
Code (DTC) List - Vehicle).
3. Observe the scan tool Misfire Current Cyl. 1-6 parameters. The Misfire Current Counters should not be incrementing.
4. Engine idling, perform the cylinder power balance test with a scan tool to isolate the misfiring cylinder. The engine speed should change
when each injector is disabled.
5. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the
conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Verify that the following conditions do not exist:
* Vacuum hose splits, kinks, and incorrect connections
* Engine vacuum leaks
* Crankcase ventilation system for vacuum leaks
* Fuel pressure that is too low or too high-Refer to Fuel System Diagnosis (See: Powertrain Management/Computers and Control
Systems/Testing and Inspection/Component Tests and General Diagnostics/Fuel System Diagnosis).
* Contaminated Fuel-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) (See: Powertrain Management/Computers and
Control Systems/Testing and Inspection/Component Tests and General Diagnostics/Alcohol/Contaminants-in-Fuel Diagnosis (with
Special Tool))Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) (See: Powertrain Management/Computers and Control
Systems/Testing and Inspection/Component Tests and General Diagnostics/Alcohol/Contaminants-in-Fuel Diagnosis (without Special
Tool)).
* Exhaust system restrictions
瀚慖f you find any of the above conditions, repair as necessary.
2. Ignition OFF, remove the T8 ignition coil of the misfiring cylinder, but leave the electrical connector connected.
3. Inspect the ignition coil boot for the following conditions:
* Holes
* Tears
* Carbon tracking
* Oil contamination
* water intrusion
瀚慖f you find any of the above conditions, repair as necessary.
4. Install the J 26792 - Spark Tester to the boot of the appropriate T8 ignition coil and ground.
Note: An erratic or weak spark is considered a no spark condition.
5. Attempt to start the engine and observe the J 26792 - Spark Tester. The spark tester should spark.
瀚慖f there is no spark, refer to Electronic Ignition System Diagnosis (See: Powertrain Management/Computers and Control
Systems/Testing and Inspection/Component Tests and General Diagnostics/Electronic Ignition System Diagnosis) for diagnosis of the
ignition coil.
6. Ignition OFF, remove the spark plug from the misfiring cylinder. Verify that the spark plug does not exhibit the following conditions:
* Gas, coolant, or oil fouled-Refer to Spark Plug Inspection (See: Engine, Cooling and Exhaust/Engine/Tune-up and Engine Performance
Checks/Spark Plug/Testing and Inspection).
* Cracked, worn, incorrectly gapped-Refer to Ignition System Specifications (See: Powertrain Management/Ignition
System/Specifications).
瀚慖f there is a condition with the spark plug, replace the spark plug.
7. Exchange the suspected spark plug with another cylinder that is operating correctly.
8. Engine idling, observe the scan tool Misfire Current Counter parameters. The misfire should not follow the spark plug exchange.
瀚慖f the misfire follows the spark plug, replace the spark plug.
