Iveco 278 – Engine ECU / EDC (Electronic Diesel Control): Poor combustion of fuel-air mixture in cylinder 4

The engine control system has detected a cylinder contribution or balance issue specifically isolated to the 4th cylinder, meaning it is not generating the expected power during its power stroke.

• Iveco Stralis
• Iveco EuroCargo
• Iveco Trakker
• Iveco Daily

1. 1

   Run a cylinder balance/contribution test using an Iveco EASY diagnostic tool (or equivalent) to confirm cylinder 4 is underperforming

2. 2

   Inspect the wiring harness and connector leading to the cylinder 4 fuel injector for chafing, corrosion, or poor pin fitment

3. 3

   Remove the valve cover and check the valve clearances (lash) for cylinder 4, ensuring there is no mechanical failure such as a bent pushrod, damaged rocker arm, or broken valve spring

4. 4

   Perform a relative or manual compression test on cylinder 4 to rule out internal engine wear (e.g., worn piston rings or burnt valves)

5. 5

   Check the fuel rail pressure and ensure fuel quality is good

1. 1

   Disconnect the vehicle's batteries.

2. 2

   Remove the valve cover to access the fuel injectors.

3. 3

   Disconnect the electrical connector from the cylinder 4 fuel injector.

4. 4

   Remove the high-pressure fuel line connected to the cylinder 4 injector.

   Cap the rail and line to prevent contamination.

5. 5

   Remove the injector hold-down clamp and carefully extract the fuel injector from the cylinder head.

6. 6

   Clean the injector bore thoroughly, ensuring the old copper sealing washer is removed and no debris falls into the cylinder.

7. 7

   Install the new fuel injector with a new copper sealing washer and new O-rings.

8. 8

   Reinstall the injector hold-down clamp and torque to OEM specifications.

9. 9

   Reconnect the high-pressure fuel line and electrical connector.

10. 10

    Reinstall the valve cover with a new gasket.

11. 11

    Reconnect the batteries.

12. 12

    Use your diagnostic scan tool to program the new injector's IMA (Injector Quantity Compensation) code into the EDC.

    Crucial Step

13. 13

    Clear the 0278 fault code and test drive the vehicle to verify the repair.