Case IH 3851 – Engine Control Unit (ECU) / EDC (Electronic Diesel Control): Zero Fuel Calibration by Lambda (ZFL): DFC reporting error state on comparing energizing time to Min value injector 4

This fault indicates an anomaly during the engine's self-calibration process. The engine controller has detected that the energizing time required for cylinder 4 has dropped below the minimum acceptable threshold, which typically means Injector 4 is mechanically worn, leaking, or has an electrical resistance issue causing it to flow too much fuel at minimum pulse widths.

• Farmall
• Farmall 75A
• Farmall 75C
• Farmall 115U Pro EP
• Magnum
• Maxxum
• SR175
• SR200
• SR220
• SR250
• SV250
• SV300
• TR270
• TR320
• TV380

1. 1

   Check fuel supply and pressure to ensure there is no air in the system and low-pressure delivery is above 4.0 psi. Inspect fuel pre-filters and main filters for restrictions.

2. 2

   Inspect the wiring harness and connector for Injector 4 for chafing, shorts to ground, or loose pins that could alter electrical resistance.

3. 3

   Perform an injector leak-off (return flow) test to physically verify if Injector 4 is bypassing too much fuel.

4. 4

   If the EDC was recently replaced or flashed, use the Electronic Service Tool (EST) to restore the self-learning parameters for the Zero Fuel Calibration.

1. 1

   Preparation

   Disconnect the negative battery cable. Clean the area around the fuel rail and injectors thoroughly to prevent debris from entering the fuel system.

2. 2

   Disconnect Lines

   Disconnect the electrical connector from Injector 4. Remove the high-pressure fuel line connecting the fuel rail to the injector. Disconnect the fuel leak-off (return) line.

3. 3

   Remove the Injector

   Unscrew the injector support fastening screws/studs. Disassemble the injector hold-down brackets/supports and carefully pull the injector out of the cylinder head.

4. 4

   Install New Injector

   Install new copper sealing washers/O-rings on the new injector. Insert the injector into the bore, ensuring that the fuel return holes all face the correct, uniform direction.

5. 5

   Reassembly

   Reinstall the injector hold-down bracket and torque the fastening screws to the OEM specification. Reconnect the high-pressure fuel line, the leak-off line, and the electrical connector.

6. 6

   Bleed and Calibrate

   Bleed the fuel system of air. Connect the Case IH Electronic Service Tool (EST) and enter the new injector's IMA (calibration) code into the EDC so the module knows the flow characteristics of the new injector. Clear the 3851 fault code and test run the machine.