10-22-2025, 06:27 PM
Ford LRG-425 EFI Engine Overview
The Ford LRG-425 is a 2.5-liter inline-four industrial engine widely used in aerial lifts, generators, and construction equipment. Originally carbureted, later versions adopted electronic fuel injection (EFI) systems to meet emissions standards and improve cold-start performance. In JLG boom lifts like the 450AJ, the LRG-425 was paired with an E-controls engine management system (EPM), Bosch throttle body, oxygen sensor, and a suite of modern sensors including MAP, crank, cam, and coolant temperature.
Ford Motor Company, founded in 1903, has long supplied industrial engines for OEMs like JLG, Genie, and Terex. The LRG-425 remains in service across North America, though many units have undergone EFI retrofits or ECM upgrades, complicating diagnostics.
Common Symptoms and Initial Observations
A recurring issue with retrofitted LRG-425 engines is erratic throttle behavior and shutdown after startup. When the key is turned to “Run,” the throttle body may cycle open and shut rapidly. Once started, the engine idles high, runs rough, and shuts off within 20 seconds. Disconnecting the throttle body and plugging in a spare unit often allows the engine to idle normally, suggesting a fault in the throttle control loop or EPM logic.
Sensor Integrity and Wiring Checks
Before condemning the EPM, technicians should verify:
Diagnostic Tools and Software Interface
To access fault codes and live data, technicians use the FPP Display software via a CAN interface. The ECOM CANCapture device is a proven solution, supporting both CAN and RS232 protocols. Once connected, the software scans available ports and displays diagnostic trouble codes (DTCs).
In one case, active DTCs included:
Terminology Notes
In North Carolina, a technician struggled with a similar system that flooded on startup. The engine only ran when started on propane and tricked into switching to gasoline. ERD Ltd., a repair shop specializing in E-controls modules, confirmed the ECM and throttle body were functional but warned that connector pins often fail due to vibration and corrosion. After inspecting the ECM connectors and confirming pin tension, the technician restored reliable gasoline starts.
Recommendations for Technicians and Owners
Diagnosing EFI faults on the Ford LRG-425 engine requires a blend of mechanical insight and electronic fluency. With proper tools, software, and attention to connector integrity, technicians can resolve even complex issues. As these engines age and retrofits become more common, understanding the E-controls system and its quirks is essential for keeping boom lifts and industrial platforms running reliably.
The Ford LRG-425 is a 2.5-liter inline-four industrial engine widely used in aerial lifts, generators, and construction equipment. Originally carbureted, later versions adopted electronic fuel injection (EFI) systems to meet emissions standards and improve cold-start performance. In JLG boom lifts like the 450AJ, the LRG-425 was paired with an E-controls engine management system (EPM), Bosch throttle body, oxygen sensor, and a suite of modern sensors including MAP, crank, cam, and coolant temperature.
Ford Motor Company, founded in 1903, has long supplied industrial engines for OEMs like JLG, Genie, and Terex. The LRG-425 remains in service across North America, though many units have undergone EFI retrofits or ECM upgrades, complicating diagnostics.
Common Symptoms and Initial Observations
A recurring issue with retrofitted LRG-425 engines is erratic throttle behavior and shutdown after startup. When the key is turned to “Run,” the throttle body may cycle open and shut rapidly. Once started, the engine idles high, runs rough, and shuts off within 20 seconds. Disconnecting the throttle body and plugging in a spare unit often allows the engine to idle normally, suggesting a fault in the throttle control loop or EPM logic.
Sensor Integrity and Wiring Checks
Before condemning the EPM, technicians should verify:
- Throttle Position Sensor (TPS): Integrated into the throttle body; must show smooth voltage sweep.
- MAP Sensor: Should respond to vacuum changes; check for 5V reference and ground.
- Crank and Cam Sensors: Must produce consistent waveform signals; use an oscilloscope if available.
- Coolant and Intake Temp Sensors: Resistance should vary with temperature; check against spec tables.
Diagnostic Tools and Software Interface
To access fault codes and live data, technicians use the FPP Display software via a CAN interface. The ECOM CANCapture device is a proven solution, supporting both CAN and RS232 protocols. Once connected, the software scans available ports and displays diagnostic trouble codes (DTCs).
In one case, active DTCs included:
- 311, 313, 315, 321: Injector open or short to ground (cylinders 1–4)
- 412: Spark coil 1 primary shorted
Terminology Notes
- EPM (Engine Performance Module): A proprietary ECM used by E-controls to manage ignition and fuel delivery.
- CAN Bus: A communication protocol used in automotive and industrial systems for real-time data exchange.
- DTC (Diagnostic Trouble Code): A standardized fault code indicating system errors.
In North Carolina, a technician struggled with a similar system that flooded on startup. The engine only ran when started on propane and tricked into switching to gasoline. ERD Ltd., a repair shop specializing in E-controls modules, confirmed the ECM and throttle body were functional but warned that connector pins often fail due to vibration and corrosion. After inspecting the ECM connectors and confirming pin tension, the technician restored reliable gasoline starts.
Recommendations for Technicians and Owners
- Use FPP Display with ECOM Interface: Enables full access to fault codes and live data.
- Inspect ECM Connectors Closely: Pin tension and corrosion are common failure points.
- Confirm Component Presence: Some DTCs may appear due to unused circuits—verify actual hardware.
- Document Sensor Voltages and Waveforms: Helps isolate intermittent faults.
- Consult ERD or Similar Repair Shops: For ECM bench testing and refurbishment.
Diagnosing EFI faults on the Ford LRG-425 engine requires a blend of mechanical insight and electronic fluency. With proper tools, software, and attention to connector integrity, technicians can resolve even complex issues. As these engines age and retrofits become more common, understanding the E-controls system and its quirks is essential for keeping boom lifts and industrial platforms running reliably.
