why does my Ford Mustang S550 (2015-2023) engine misfire at idle

Solution

1. Preparation

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

2. Inspect and Replace Spark Plugs

• Remove the engine cover if applicable.
• Use a socket wrench to remove the spark plug wires or ignition coil harness.
• Carefully unscrew the spark plugs using a spark plug socket.
• Inspect the condition of the spark plugs; replace if fouled or worn beyond specifications.
• Install new spark plugs, ensuring they are gapped correctly according to manufacturer specifications (typically 0.030-0.035 inches).
• Reattach the ignition coils or spark plug wires securely.

3. Test and Replace Ignition Coils

• If the spark plugs are in good condition, test each ignition coil using a multimeter. Resistance should be within specified ranges (consult service manual for values).
• If any coils are faulty, replace them with OEM parts.
• Reconnect the ignition coil connectors.

4. Check and Replace Fuel Injectors

• Remove the fuel rail by unscrewing the retaining bolts and disconnecting the fuel lines (follow safety procedures to relieve fuel pressure).
• Inspect fuel injectors for clogs; clean or replace them as necessary.
• Reinstall the fuel rail and ensure all connections are secure.

5. Conduct a Vacuum Leak Test

• Check all vacuum hoses for cracks or disconnections. Replace any damaged hoses.
• Use a smoke tester if available to find leaks in the intake manifold.