why does my Honda Accord have a rough idle when warm

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical hazards.

2. Clean or Replace the IAC

• Sub-steps:
  1. Locate the idle air control valve (IAC) on the throttle body.
  2. Remove the electrical connector and the mounting screws.
  3. If cleaning, use throttle body cleaner to remove carbon deposits; if replacing, install the new IAC.
  4. Reinstall the IAC and reconnect the electrical connector.

3. Inspect and Replace Vacuum Hoses

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks or disconnections.
  2. Replace any damaged hoses with new vacuum hoses of the same diameter.
  3. Ensure all connections are secure.

4. Test and Adjust TPS

• Sub-steps:
  1. Locate the throttle position sensor (TPS) on the throttle body.
  2. Use a multimeter to check the voltage output at the TPS while moving the throttle plate.
  3. If the voltage is out of specification, adjust or replace the TPS as needed.

5. Check Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Start the engine and observe the fuel pressure; it should meet manufacturer specifications.
  3. If the pressure is low, check the fuel pump and filter for issues.

6. Inspect and Replace Spark Plugs

• Sub-steps:
  1. Remove the ignition coil or spark plug wires to access the spark plugs.
  2. Inspect the spark plugs for wear, fouling, or incorrect gap.
  3. Replace with new spark plugs that match manufacturer specifications.