how to fix a misfire in GMC Sierra T1XX (2019-Present) related to P0301?

Learn how to diagnose and fix P0301 cylinder 1 misfire in GMC Sierra T1XX. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool before starting any work.

2. Replace Spark Plug

• Tools Required: Socket set, torque wrench, ratchet, spark plug socket.
• Remove the ignition coil from cylinder 1 by unscrewing the mounting bolts and disconnecting the electrical connector.
• Use the spark plug socket to remove the old spark plug from cylinder 1.
• Inspect the spark plug gap and replace it with a new spark plug, ensuring it is gapped to the manufacturer’s specifications (typically around 0.040 in or 1.0 mm).
• Torque the new spark plug to the manufacturer's specifications (usually around 11-15 lb-ft or 15-20 Nm).

3. Check/Replace Ignition Coil

• If the spark plug replacement does not resolve the issue, test the ignition coil for cylinder 1.
• If faulty, remove the coil by unscrewing the bolts and disconnecting the electrical connector.
• Install the new ignition coil and reconnect the electrical connector securely.

4. Inspect Fuel Injector

• Remove the fuel rail if necessary to access the fuel injector for cylinder 1.
• Check for proper operation by testing the injector resistance with a multimeter (should be within manufacturer’s specifications).
• Replace the injector if it is clogged or malfunctioning.

5. Perform Compression Test

• If issues persist, perform a compression test on cylinder 1 using a compression gauge.
• If compression is low, further investigation is needed for potential internal issues (e.g., valve problems, piston rings).