Case IH 3846 – ENGINE ECU: Injector - Zero Fuel Calibration by Lambda (ZFL): DFC reporting error state on comparing energizing time to Max value injector 3

The engine control system is performing a Zero Fuel Calibration by Lambda (ZFL) and has detected that the energizing time required for Injector 3 has exceeded the maximum allowable limit, indicating a mechanical response fault within the injector, excessive wear, or a localized fuel delivery/leakage issue affecting cylinder 3.

• Farmall
• Maxxum
• Puma
• Steiger
• Patriot
• SR200
• SR220
• SR250
• SV250
• SV300
• TR270
• TR320
• TV380
• 521E/F
• 621E/F
• 721E/F
• 821F

1. 1

   Check for air ingress by installing a clear test line between the low-pressure fuel supply and the high-pressure pump to observe for air bubbles entering the system

2. 2

   Verify the fuel delivery performance of the gear supply (lift) pump and ensure the fuel supply pressure to the high-pressure pump meets specifications (minimum 5 bar / 72 psi between filter and high-pressure pump on some models)

3. 3

   Inspect the fuel inlet and return lines for restrictions, and check the primary and secondary fuel filters

4. 4

   Measure the fuel leakage (return) rate from the electronically controlled injectors to isolate if Injector 3 is leaking excessively

5. 5

   Inspect the wiring harness and connectors to Injector 3 for open circuits, short circuits, or poor pin tension, which can cause mechanical response faults

1. 1

   Relieve Pressure

   Ensure the engine is off and the high-pressure fuel system is depressurized before opening any lines.

2. 2

   Remove Components

   Disconnect the electrical connector and the high-pressure fuel line to Injector 3. Cap all open fuel ports immediately to prevent contamination.

3. 3

   Extract Injector

   Remove the hold-down clamp and carefully extract Injector 3 from the cylinder head.

4. 4

   Install New Injector

   Install the replacement injector with a new sealing washer/O-ring. Torque the hold-down clamp and high-pressure fuel lines to the exact OEM specifications for your specific engine model.

5. 5

   Program the ECM

   Use the electronic service tool to write the new injector's specific calibration code (IQA code) into the Engine Control Module.

6. 6

   Recalibrate and Clear

   Follow the appropriate service tool procedure to restore self-learning parameters, bleed the fuel system, and clear the 3846 fault code.