how to fix P0304 cylinder 4 misfire in my Ram 1500 DT (2019-Present)?

Learn how to diagnose and fix P0304 cylinder 4 misfire in Ram 1500 DT. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts needed.
• Disconnect the negative battery terminal to prevent electrical shorts.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Compression gauge
• Multimeter
• Spark plug socket
• Inspection mirror (optional)
• Clean rags

2. Replace Spark Plug

1. Remove the engine cover (if applicable) using the socket set.
2. Locate cylinder 4's spark plug and remove the ignition coil by unbolting and disconnecting the electrical connector.
3. Use the spark plug socket to remove the old spark plug.
4. Inspect the new spark plug for the correct gap and install it, ensuring it is torqued to the manufacturer's specifications (usually around 13-15 lb-ft).
5. Reinstall the ignition coil and reconnect the electrical connector.

3. Inspect and Replace Ignition Coil (if necessary)

1. If the misfire persists after replacing the spark plug, remove the ignition coil from cylinder 4.
2. Swap the ignition coil with another cylinder and observe if the misfire code follows the coil.
3. If it does, replace the ignition coil for cylinder 4 with a new one, ensuring proper installation and torque of mounting bolts.

4. Check Fuel Injector (if necessary)

1. If the issue continues, verify the fuel injector's operation by disconnecting the electrical connector and using a multimeter to check for voltage.
2. If no voltage is present, trace the wiring back to the engine control module (ECM).
3. If voltage is present but the injector is non-functional, remove and replace the fuel injector for cylinder 4.

5. Compression Test (if necessary)

1. If all components seem functional, perform a compression test on cylinder 4.
2. If compression is low, further investigation may be needed for internal engine issues such as a blown head gasket or valve problems.