why is my GMC Sierra T1XX (2019-Present) shaking when idling?

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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface, and the engine is off.
• Disconnect the battery to prevent electrical shorts.

2. Check Engine Mounts

• Tools Required: Socket set, pry bar
• Remove the bolts securing the engine mount to the engine.
• Use a pry bar to carefully lift the engine to inspect the mount.
• Replace any damaged or worn engine mounts with new units.
• Reinstall bolts to the manufacturer's torque specifications (typically specified in the vehicle's service manual).

3. Inspect Spark Plugs and Ignition System

• Tools Required: Spark plug socket, torque wrench
• Remove the spark plugs using the spark plug socket.
• Inspect spark plugs for wear or fouling; replace if necessary.
• Check ignition coils for proper function; replace any faulty coils.
• Reinstall spark plugs and torque to the manufacturer's specifications.

4. Examine Fuel System

• Tools Required: Fuel pressure gauge
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position without starting the engine to check fuel pressure.
• Compare the reading to the manufacturer's specifications; replace the fuel filter if pressure is low.
• Inspect fuel injectors for clogs or leaks and clean or replace as needed.

5. Address Vacuum Leaks

• Tools Required: Smoke machine or carburetor cleaner
• Use a smoke machine to identify vacuum leaks; if unavailable, spray carburetor cleaner around intake connections while the engine is running to listen for RPM changes.
• Repair or replace any damaged hoses or gaskets found during inspection.