P0301 Cylinder 1 Misfire

When monitored DTC P0301 Cylinder 1 Misfire, with the engine running, the adaptive numerator has been succesfully updated. Set conditions, the variation in crankshaft speed between each cylinder exceeds a calibrated value, based on engine rpm load.Default Actions, the MIL light illuminate.

Possible Causes:

• ASD relay output.
• Injector control circuit.
• Coil control circuit.
• Ignition wire.
• Spark plug.
• Ignition coil.
• Fuel delivery system issue.
• Fuel injector.
• Engine mechanical.
• Powertrain Control Module (PCM).

Diagnose code P0301 Cylinder 1 Misfire

Step 1. Check for an active DTC

Diagnose and repair any other active component or circuit DTC before continuing with this procedure. Turn the ignition on, with the scan tool, read DTC. Operate the vehicle under conditions similiar to which the DTC was set. With the scan tool, view the misfire monitor to see which cylinders are effected. It may be necessary to test drive the vehicle within the DTC monitoring conditions in order for this DTC to set or to show misfires on a particular cylinder.

Are there excessive misfires shown or is the DTC pending at this time?

Yes, go to step 2.

No, perform the the PCM intermittent condition.

Step 2. Visual Inspection

Anything that effects the speed of the crankshaft can cause a misfire DTC. When a misfire is detected for a particular cylinder, the PCM will shut down the injector control circuit for that cylinder. Misfires detected during a decleration are indicators of mechanical concers.

Visually inspect the engine for any of the following conditions:

• Worn sepertine belt.
• Binding engine-driven accessories:A/C compressor, P/S pump, water pump.
• Misalignment of the water pump, P/S pump and A/C compressor pulleys.
• Corroded PCM power and ground.
• Improper CKP, CMP, MAP, and TP sensor mounting.
• Poor connector/terminal to component connection for CKP sensor, CMP sensor, MAP sensor, TP sensor, fuel injector, ignition coil, etc.
• Vacuum leaks.
• Restricted exhaust system.
• Restricted air induction system.
• Internal engine component failures.
• Overfilled engine oil or transmission.
• Extremely out of balance tires or warped brake rotors.

Were any of the above conditions present?

Yes, repair as necessary.

No, go to step 3.

(Sorry!!! Step 3-5, refer to code P0302)

Step 3. Ignition system operation

Step 4. Spark plug
Step 5. Fuel pressure check

(Sorry!!! Step 6-8, refer to code P0303)

Step 6. Fuel pressure leak down

Step 7. Fuel injector operation

Step 8. Engine mechanical

(Sorry!!! Step 9-11, refer to code P0304)

Step 9. Fuel injector control

Step 10. Injector control circuit

Step 11. Fuel supply line restricted

(Sorry!!! Step 12-14, refer to code P0305)

Step 12. Fuel pump inlet strainer

Step 13. ASD relay output circuit

Step 14. Ignition coil

(Sorry!!! Step 15-17, refer to code P0306)

Step 15. Coil control 1 circuit shorted to ground

Step 16. Coil control 1 circuit open

Step 17. Powertrain Control Module (PCM)

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