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. Other possible causes such as uncommanded Exhaust Gas Recirculating (EGR) flow can also cause a misfire. 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:
If the Powertrain Control Module (PCM) detects that the variation in crankshaft speed between each cylinder exceeds a calibrated value, based on engine rpm and load, a fault is set.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
1. DTC IS ACTIVE
1. Diagnose and repair any other active component or circuit DTCs before continuing with this procedure.
2. Turn the ignition on.
3. With the scan tool, select View DTCs. Copy DTC and Freeze Frame information.
4. Start the engine and allow it to reach operating temperature.
WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in possible serious or fatal injury.
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.
5. 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. When a misfire is detected, the PCM will shut down the injector control circuit for the misfiring cylinder. Misfire may occur and may not be caused by component failure. Any of the following conditions can cause a misfire.
Inspect the engine for any of the following conditions:
- Worn serpentine belt
- Misalignment or binding water pump, P/S pump or A/C compressor pulleys
- Improper CKP, CMP, or MAP Sensor mounting.
- Poor connector/terminal to component connection for CKP sensor, CMP sensor, MAP sensor, throttle body, fuel injector, ignition coil, etc.
- Corroded PCM power or ground circuits.
- Vacuum leaks.
- Restriction in the air induction or exhaust system.
- Internal engine component malfunction.
- Moisture on ignition system components
- Insufficient fuel
- Low quality fuel
- 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 FUEL PRESSURE LEAK DOWN and FUEL DELIVERY SYSTEM OUTPUT - FLOW TEST. Fuel Pressure Leak Down Fuel Delivery System Output - Flow Test
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. Checking The Ignition Coil Operation
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. 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.
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Monitor the scan tool data relative to the components tested in this procedure and wiggle test the wiring and connectors.
5. Look for the data to change or for a DTC to set during the wiggle test.
6. 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). Powertrain Control Module - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.