my GMC Sierra T1XX (2019-Present) has poor acceleration, could it be a misfire?

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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, fuel pressure gauge, multimeter, vacuum gauge.
• Disconnect the negative battery terminal to prevent electrical shock.
• Allow the engine to cool down if recently operated.

2. Replace Spark Plugs

1. Remove the engine cover if applicable.
2. Disconnect ignition coil connectors.
3. Remove ignition coils using the socket set.
4. Unscrew and extract spark plugs using the socket.
5. Inspect the old spark plugs for wear; clean or replace as necessary.
6. Install new spark plugs, ensuring proper torque (typically 13 lb-ft).
7. Reinstall ignition coils and connect the electrical connectors.

3. Test and Replace Ignition Coils (if necessary)

1. Use a multimeter to test each ignition coil's primary and secondary resistance.
2. If any coils are out of specification, remove and replace them.
3. Reconnect all components and ensure secure connections.

4. Inspect and Clean Fuel Injectors

1. Use a fuel pressure gauge to check fuel pressure at the rail; compare with manufacturer specifications.
2. If pressure is low, inspect and replace the fuel filter if clogged.
3. Use an injector cleaner or remove injectors to clean them manually if necessary.
4. Reinstall injectors and ensure all connections are secure.

5. Check for Vacuum Leaks

1. Inspect vacuum lines visually for cracks or disconnections.
2. Use a vacuum gauge to check for low readings, which can indicate a leak.
3. Repair or replace any faulty vacuum lines or components as needed.