what causes rough idle on my Acura MDX YF3 (2022-Present) when cold

Symptoms

• Rough Idle: The engine may shake or vibrate noticeably when idling.
• Check Engine Light: The dashboard may illuminate with a check engine warning.
• Poor Fuel Economy: Increased fuel consumption may occur.
• Stalling: The engine may stall shortly after starting, particularly when cold.
• Unstable RPM: The tachometer may fluctuate erratically during idle.

Diagnostic Steps

1. Scan for Error Codes:

   • Use an OBD-II scanner to check for any diagnostic trouble codes (DTCs) that may point to specific issues.

2. Inspect Fluid Levels:

   • Check engine oil, coolant, and fuel levels. Ensure they are within specifications.

3. Inspect Air Filter:

   • Check the air filter for blockages or dirt that could restrict airflow.

4. Check for Vacuum Leaks:

   • Inspect vacuum hoses for cracks or disconnections that could lead to an improper air-fuel mixture.

5. Test Fuel Pressure:

   • Use a fuel pressure gauge to measure fuel pressure at the fuel rail to ensure proper delivery.

6. Inspect Spark Plugs:

   • Remove and inspect spark plugs for wear or carbon buildup. This may indicate issues with combustion.

7. Monitor Engine Sensors:

   • Use a multimeter to test the Mass Air Flow (MAF) sensor and Throttle Position Sensor (TPS) for proper operation.

8. Check Idle Air Control Valve (IACV):

   • Inspect the IACV for proper operation, as it regulates the engine's idle speed.

Repair Instructions

1. Address any Error Codes:

   • Follow the specific diagnostic procedures for any identified trouble codes.

2. Replace Air Filter (if necessary):

   • Disconnect the air intake duct and remove the old air filter. Install a new filter and reassemble.

3. Fix Vacuum Leaks:

   • Replace any damaged vacuum hoses or fittings.

4. Repair or Replace Fuel Pump (if fuel pressure is low):

   • Relieve fuel system pressure.
   • Disconnect the battery.
   • Remove the fuel pump access cover (if applicable) or drop the fuel tank.
   • Replace the fuel pump and reassemble.

5. Replace Spark Plugs (if worn):

   • Remove the ignition coils (if applicable).
   • Use a spark plug socket to remove old plugs, and install new plugs with the proper torque specifications.

6. Clean or Replace IACV (if malfunctioning):

   • Remove the IACV from the throttle body.
   • Clean it with throttle body cleaner or replace it if it’s not functioning properly.

Estimated Time for Repair

• Depending on the issue, repairs may take anywhere from 1 to 3 hours, including diagnostics and parts replacement.

Safety Warnings

• Ensure the vehicle is parked on a level surface and the engine is off before performing any inspections.
• Always wear safety glasses and gloves when handling fuel or working on the engine.
• Be cautious of hot components and fluids, especially after the engine has been running.