Test Description

The numbers below refer to the step numbers on the diagnostic table.

2: This step determines if there is a current misfire condition. The scan tool will display increasing counts in the Total Misfire Current Counter parameter if a misfire is occurring.

3: If the Total Misfire Current Counter parameter is incrementing, but the engine is NOT misfiring, this could be caused by an excessive vibration from other sources than the engine.

4: If the actual CKP variation values are not within the learned values, the Total Misfire Current Counter parameter may increment.

Step	Action	Values	Yes	No
1	Did you perform the Diagnostic System Check - Engine Controls?	-	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	IMPORTANT: A misfire may only occur when the engine is under a load. An engine load may be necessary to verify the condition. Turn ON the ignition, with the engine OFF. Clear the DTCs with a scan tool. Start the engine. Monitor the Misfire Current Cylinder parameters with a scan tool. Are any of the Misfire Current Cylinder counters incrementing?	-	Go to Step 4	Go to Step 3
3	Observe the Freeze Frame/Failure Records for this DTC. Turn the ignition OFF for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	-	Go to Step 4	Go to Diagnostic Aids
4	Is the engine misfiring?	-	Go to Step 5	Go to Crankshaft Position System Variation Learn
5	Are DTCs P0201, P0202, P0203, P0204, P0317, P0336, P0337, P0341, P0342, P0351, or P0352 set?	-	Go to Diagnostic Trouble Code (DTC) List	Go to Step 6
6	Is there an abnormal engine noise?	-	Go to Symptoms - Engine Mechanical in Engine Mechanical - 1.8L (L79)	Go to Step 7
7	Is there more than one cylinder specific misfire DTC set?	-	Go to Step 8	Go to DTC P0301-P0304
8	Are there any heated oxygen sensor (HO2S) DTCs Set?	-	Go to Diagnostic Trouble Code (DTC) List	Go to Step 9
9	Inspect the following components: The vacuum hoses and seals for splits, restrictions, and improper connections. The intake manifold for vacuum leaks The crankcase ventilation system for vacuum leaks-Refer to Crankcase Ventilation System Inspection/Diagnosis . Test for the correct fuel pressure. Refer to Fuel System Diagnosis . Test the fuel for contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (w/o Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (w/ Special Tool) . Inspect for fouled or damaged spark plugs. Determine what caused the spark plugs to foul. Refer to Spark Plug Inspection . Inspect engine control module (ECM) grounds for corrosion and loose connections-Refer to Power Distribution Schematics in Wiring Systems. The exhaust system for restrictions-Refer to Restricted Exhaust in Engine Exhaust. Did you find and correct the condition?	-	Go to Step 10	Go to Symptoms - Engine Mechanical in Engine Mechanical - 1.8L (L79)
10	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	-	Go to Step 2	Go to Step 11
11	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List	System OK