how to resolve P0304 misfire code on Porsche Cayenne E3 (2018-Present)

Learn how to diagnose and fix P0304 cylinder 4 misfire in Porsche Cayenne E3. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative terminal of the battery to prevent electrical shorts.
• Ensure the vehicle is parked on a level surface and secure it with wheel chocks.

2. Inspect and Replace Ignition Components

• Inspect Spark Plug:

  • Remove the spark plug from cylinder 4 using a spark plug socket.
  • Check for signs of wear, fouling, or damage.
  • Replace with OEM spark plug if necessary (Torque to 30 Nm).

• Inspect Ignition Coil:

  • Disconnect the electrical connector from the ignition coil.
  • Remove the ignition coil using a socket set.
  • Inspect for cracks or carbon tracking and replace if necessary.

3. Check and Replace Fuel Injector

• Remove Fuel Injector:

  • Relieve fuel system pressure by removing the fuel pump relay and starting the engine until it stalls.
  • Disconnect the fuel injector connector and remove the injector retaining clips.
  • Carefully pull out the fuel injector from the intake manifold.

• Install New Injector:

  • Lubricate the O-rings of the new fuel injector with clean engine oil.
  • Insert the new injector into the manifold, ensuring it's seated correctly.
  • Reinstall the retaining clips and reconnect the electrical connector.

4. Perform a Compression Test

• Compression Testing:

  • Remove the spark plug from cylinder 4.
  • Install the compression gauge and crank the engine for several seconds.
  • Compare the reading with manufacturer specifications (should be approximately 12-16 bar).

• Address Any Compression Issues:

  • If compression is low, further investigation into valve seating or head gasket integrity may be necessary.

5. Reassemble and Reconnect

• Reinstall any components that were removed during the inspection and repair process.
• Reconnect the negative terminal of the battery.