P0301
P0301-CYLINDER 1 MISFIRE
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The misfire detection monitor software strategy in the Powertrain Control Module (PCM) is designed to detect an engine misfire. The PCM uses the Crankshaft (CKP) and Camshaft (CMP) sensors to determine when an engine misfire event is occurring and determine individual misfire events by monitoring the crankshaft rotational speed. A misfire is nothing more than a lack of combustion, which can be caused by poor fuel quality or metering, low compression, lack of spark or unmetered air entering the engine. On engines equipped with Exhaust Gas Recirculation (EGR), another possible cause is unwanted EGR flow. In the case of multiple cylinders misfiring or the PCM not determining the specific cylinder misfiring, P0300 Multiple Cylinder Misfire will set.
- When Monitored:
Any time the engine is running, and the adaptive numerator has been successfully updated.
- Set Condition:
The threshold to set the fault is application specific; it is tied to the level of misfire that will cause emissions to increase to 1.5 times the standard or in some cases 1%. It is always a two trip fault above the calibrated RPM. It takes one fail to set a Pending Fault and two trips to set the MIL. Three good trips to turn off the MIL.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
Diagnostic Test
1. CHECK FOR AN ACTIVE DTC
1. Diagnose and repair any other active component or circuit DTCs before continuing with this procedure.
2. Turn the ignition on, engine not running.
3. With the scan tool, select View DTCs. Copy DTC and Freeze Frame information.
NOTE: Attempt to operate the vehicle under conditions similar to which the DTC was set.
NOTE: It may be necessary to test drive the vehicle within the DTC monitoring conditions in order for this DTC to set.
4. With a scan tool, select View DTCs.
Is the status Active for this DTC?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure Intermittent Condition Test.
2. DIAGNOSTIC INSPECTION
NOTE: Anything that affects the speed of the crankshaft can cause this DTC to set.
NOTE: When a misfire is detected, the PCM will shut down the injector control circuit for the misfiring cylinder.
NOTE: Misfire may occur and may not be caused by component failure. Any of the following conditions can cause a misfire:
- Worn serpentine belt.
- Misalignment or binding generator or A/C compressor pulleys.
- Improper CKP, CMP, MAP, or TP Sensor mounting.
- Poor connector/terminal to component connection for CKP sensor, CMP sensor, MAP sensor, TP sensor, fuel injector, ignition coil, etc.
- Corroded PCM power or ground circuits.
- Intake manifold vacuum leaks.
- Restriction in the air induction or exhaust system.
- Internal engine component malfunction.
- Moisture on ignition system components.
- Insufficient fuel.
- Low quality fuel.
- Overfilled engine oil or transmission.
- Extremely out of balance tires or warped brake rotors.
- Manual transmission bog.
- Towing overload.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test.
No
- Go To 3
3. CHECKING THE FUEL DELIVERY SYSTEM
1. Perform the diagnostic procedures for CHECKING THE FUEL DELIVERY SYSTEM, FUEL PRESSURE LEAK DOWN and FUEL DELIVERY SYSTEM OUTPUT - FLOW TEST Testing and Inspection.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test.
No
- Go To 4
4. CHECKING THE IGNITION COIL OPERATION
1. Perform the diagnostic procedure for CHECKING THE IGNITION COIL OPERATION Testing and Inspection.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test.
No
- Go To 5
5. CHECKING THE ENGINE COOLANT TEMPERATURE SENSOR OPERATION
1. Perform the diagnostic procedure for CHECKING THE ENGINE COOLANT TEMPERATURE SENSOR OPERATION Checking The Engine Coolant Temperature Sensor Operation.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test.
No
- Go To 6
6. CHECKING THE MAP SENSOR OPERATION
1. Perform the diagnostic procedure for CHECKING THE MAP SENSOR OPERATION Checking The MAP Sensor Operation.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test.
No
- Go To 7
7. CHECKING THE OXYGEN SENSOR OPERATION
1. Perform the diagnostic procedure for CHECKING THE OXYGEN SENSOR OPERATION .
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test.
No
- Go To 8
8. CHECKING THE ENGINE MECHANICAL SYSTEM
1. Perform the diagnostic procedure for CHECKING THE ENGINE MECHANICAL SYSTEM Checking The Engine Mechanical System.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test.
No
- Go To 9
9. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors relative to the components tested in this procedure.
- Look for any chafed, pierced, pinched, or partially broken wires.
- Look for broken, bent, pushed out or corroded terminals.
- Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
- Look for the data to change or for the DTC to reset during the wiggle test.
- Perform any technical service bulletins that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Replace and program the Powertrain Control Module (PCM) .
- Perform the POWERTRAIN VERIFICATION TEST Powertrain Verification Test.