why does my Ford Mustang S550 (2015-2023) engine misfire when idling

Solution

1. Preparation

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

2. Inspect and Replace Spark Plugs

• Remove the engine cover if equipped.
• Use a spark plug socket to remove each spark plug.
• Inspect plugs for carbon build-up or wear; replace any faulty plugs with OEM specifications.
• Torque new spark plugs to the manufacturer’s specifications (typically around 12-15 lb-ft).

3. Check and Replace Ignition Coils

• Remove the ignition coil connectors by pressing the release tab.
• Unbolt and remove the ignition coils using a socket wrench.
• Inspect coils for cracks or corrosion; replace any faulty coils with OEM parts.
• Reinstall the coils and reconnect the wiring harness.

4. Clean or Replace Fuel Injectors

• If injectors are clogged, use a fuel injector cleaner or replace them.
• Remove the fuel rail (ensure fuel pressure has been relieved).
• Disconnect the fuel lines and electrical connectors from the injectors.
• Replace with new injectors if cleaning does not resolve the issue.

5. Inspect Vacuum Lines and Intake Manifold

• Visually inspect all vacuum hoses for cracks or disconnections.
• Replace any damaged hoses.
• Check the intake manifold gasket for signs of leaks and replace if necessary.

6. Test Fuel Pressure

• Connect a fuel pressure gauge to the fuel rail.
• Turn the ignition on (do not start) and check the pressure reading against manufacturer specifications.
• If pressure is low, investigate the fuel pump and filter.