how to fix Cadillac Escalade T1XX (2021-Present) rough idle at stoplights

Symptoms

• Rough idle while at a complete stop
• Engine vibrations noticeable from inside the cabin
• Potentially illuminated check engine light
• Decreased fuel efficiency
• Possible engine stalling when coming to a stop
• Increased emissions

Diagnostic Steps

1. Scan for error codes using an OBD-II scanner to identify any stored trouble codes.
2. Inspect and clean the throttle body for carbon buildup.
3. Check the condition of the spark plugs and ignition coils.
4. Measure fuel pressure using a fuel pressure gauge to ensure it's within manufacturer's specifications.
5. Inspect vacuum lines for any leaks or disconnections.
6. Test the Mass Air Flow (MAF) sensor for proper operation using a multimeter.

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.

Tools Required:

• OBD-II scanner
• Throttle body cleaner
• Socket set
• Fuel pressure gauge
• Multimeter
• Torque wrench

2. Clean Throttle Body

• Step 1: Remove the air intake duct connected to the throttle body using a socket set.
• Step 2: Spray throttle body cleaner into the throttle body while manually opening the throttle plate.
• Step 3: Wipe the interior with a clean lint-free cloth until it’s free of carbon deposits.
• Step 4: Reinstall the air intake duct and securely fasten all clamps.

3. Inspect and Replace Spark Plugs

• Step 1: Remove the engine cover if applicable.
• Step 2: Disconnect the ignition coils and remove them using a socket set.
• Step 3: Unscrew the spark plugs with a spark plug socket; inspect for wear.
• Step 4: Replace with new spark plugs, ensuring proper gap specifications are met.
• Step 5: Reinstall ignition coils and engine cover.

4. Check Fuel Pressure

• Step 1: Locate the fuel pressure test port on the fuel rail.
• Step 2: Attach the fuel pressure gauge and turn the ignition to the "ON" position without starting the engine.
• Step 3: Check the reading against manufacturer specifications; it should typically range between 55-62 psi.
• Step 4: If pressure is low, inspect the fuel pump and filter for issues.

5. Inspect and Repair Vacuum Leaks

• Step 1: Visually inspect all vacuum hoses for cracks or disconnections.
• Step 2: Use a smoke machine or carb cleaner spray around hose connections while the engine is idling to detect leaks.
• Step 3: Replace any faulty hoses or connections as needed.

6. Test Mass Air Flow Sensor

• Step 1: Disconnect the MAF sensor connector.
• Step 2: Use a multimeter to check the voltage output while the ignition is on (but engine off).
• Step 3: Compare readings with manufacturer specifications; replace if readings are out of range.