how to fix GMC Sierra T1XX (2019-Present) engine misfire

Learn how to diagnose and fix engine misfire issues in GMC Sierra T1XX (2019-Present). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

2. Replace Spark Plugs

• Remove the ignition coil(s) by unbolting them and disconnecting the electrical connector.
• Use a spark plug socket to carefully remove the old spark plugs.
• Inspect the old plugs for signs of excessive wear, fouling, or damage.
• Install new spark plugs, ensuring they are gapped to manufacturer specifications.
• Torque the plugs to the specified value (usually around 13-15 lb-ft).

3. Replace Ignition Coils (if needed)

• If any ignition coils are found to be faulty during inspection, replace them.
• Disconnect the electrical connector and remove the bolts securing the coil.
• Install the new ignition coil and reconnect the electrical connector.

4. Address Fuel System Issues

• If fuel pressure is low, replace the fuel filter or check the fuel pump for proper operation.
• If necessary, clean the fuel injectors using a fuel injector cleaning solution.

5. Check for Vacuum Leaks

• Inspect all hoses connected to the intake manifold for cracks or disconnections. Replace any damaged hoses.
• Use a smoke test to identify hidden vacuum leaks if necessary.

6. Reconnect Battery and Clear Codes

• Reconnect the battery and use the OBD-II scanner to clear any stored error codes.
• Start the engine and check for any reoccurring codes or issues.