my Ford Mustang S650 (2024-Present) has a rough idle when starting cold

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Spark Plugs

• Sub-steps:
  1. Remove the engine cover if applicable (use a socket set).
  2. Disconnect the ignition coil connectors.
  3. Remove the ignition coils using a socket wrench.
  4. Unscrew and remove the old spark plugs.
  5. Inspect the spark plug gaps and replace them with new plugs as needed (torque to manufacturer specification).

3. Clean or Replace Idle Air Control Valve

• Sub-steps:
  1. Locate the IAC valve (typically near the throttle body).
  2. Disconnect the electrical connector and remove the mounting screws.
  3. Clean the valve with throttle body cleaner or replace it if heavily carbonized.
  4. Reinstall the cleaned or new IAC valve and reconnect the electrical connector.

4. Inspect and Clean Air Intake System

• Sub-steps:
  1. Remove the air intake duct to access the throttle body.
  2. Inspect the duct for cracks or leaks and replace if necessary.
  3. Clean the throttle body interior using throttle body cleaner and a soft cloth.
  4. Reassemble the air intake system ensuring all clamps are secure.

5. Check and Replace Fuel Filter

• Sub-steps:
  1. Locate the fuel filter (usually along the fuel line).
  2. Relieve fuel system pressure by removing the fuel pump relay.
  3. Disconnect fuel lines carefully, using safety glasses to prevent fuel spray.
  4. Remove the old fuel filter and replace it with a new one, ensuring proper orientation.
  5. Reconnect fuel lines and reinsert the fuel pump relay.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Throttle body cleaner
• Screwdrivers
• Safety glasses

Parts Required:

• Spark plugs
• Idle air control valve (if necessary)
• Fuel filter

Estimated Repair Time: 3-5 hours

Safety Warnings:

• Disconnect the battery before working on electrical systems.
• Allow the engine to cool before opening any components.
• Handle fuel with care to avoid spills and fire hazards.