how to fix my Jaguar XF X260 (2015-2024) if it stalls at traffic lights

Symptoms

• Engine stalling when stopped at traffic lights
• Rough idle when the vehicle is at a standstill
• Check engine light illuminated
• Increased emissions during operation
• Poor acceleration upon resuming driving

Diagnostic Steps

1. Scan the vehicle using an OBD-II scanner to check for any stored trouble codes.
2. Inspect the throttle body for carbon buildup or obstructions.
3. Check the idle air control (IAC) valve functionality and cleanliness.
4. Test fuel pressure using a fuel pressure gauge to ensure proper fuel delivery.
5. Examine spark plugs for wear or fouling.
6. Inspect air filter for clogs or restrictions to airflow.

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to ensure safety while working on electrical components.

2. Clean Throttle Body

• Tools Required: Throttle body cleaner, soft brush, rags
• Sub-steps:
  1. Remove the air intake duct connected to the throttle body.
  2. Spray throttle body cleaner onto a clean rag or directly onto the throttle body.
  3. Use a soft brush to gently scrub any carbon buildup inside the throttle body.
  4. Wipe clean with a dry rag and reassemble the air intake duct.

3. Service the Idle Air Control Valve (IAC)

• Tools Required: Torx or socket set, electrical cleaner
• Sub-steps:
  1. Locate the IAC valve, typically mounted on the throttle body or intake manifold.
  2. Disconnect the electrical connector and remove the mounting screws.
  3. Clean the IAC valve with electrical cleaner and a rag.
  4. Reinstall the IAC valve and reconnect the electrical connector.

4. Test Fuel Pressure

• Tools Required: Fuel pressure gauge
• Sub-steps:
  1. Locate the fuel rail and find the Schrader valve.
  2. Connect the fuel pressure gauge to the Schrader valve.
  3. Turn the ignition key to the "ON" position (without starting the engine) and check the fuel pressure reading.
  4. Compare the reading to the manufacturer’s specifications (typically around 40-60 PSI for most vehicles).
  5. If the pressure is low, inspect the fuel pump and fuel filter for issues.

5. Inspect and Replace Spark Plugs

• Tools Required: Socket set, torque wrench
• Sub-steps:
  1. Remove the ignition coil cover to access the spark plugs.
  2. Disconnect the ignition coils and remove them from the spark plugs.
  3. Use a spark plug socket to remove the spark plugs.
  4. Inspect the spark plugs for wear or fouling; replace if necessary.
  5. Install new spark plugs to the manufacturer’s torque specifications and reattach the ignition coils.