Lucas 14CUX

Lucas 14CUX

Main printed circuit board of the Lucas 14CUX
Manufacturer	Lucas Industries
Type	Electronic automobile engine management
Release date	1990
Predecessor	Lucas 13CU / 14CU
Successor	Lucas/SAGEM GEMS 8 Bosch Motronic ML2.1

The Lucas 14CUX (sometimes referred to as the Rover 14CUX) is an automotive electronic fuel injection system developed by Lucas Industries and fitted to the Rover V8 engine in Land Rover vehicles between 1990 and 1995. The system was also paired with the Rover V8 by a number of low-volume manufacturers such as TVR, Marcos, Ginetta, and Morgan.

The system is also sometimes referred to as the "Rover Hot-Wire" or "Hitachi Hot-Wire", in reference to the style of airflow sensor it uses (and the sensor's manufacturer, Hitachi).

In the mid-1980s, Lucas developed the 13CU system by revising the Bosch L-Jetronic system and adding an electronic diagnostics capability to comply with California Air Resources Board requirements. The design of the 13CU also deviated from the original L-Jetronic design in that it used a hot-wire air mass sensor rather than the Jetronic's mechanical flap sensor.

The 13CU was further developed into the 14CU, which had (among other changes) an ECU that was more physically compact. The 14CU was used in US-market Range Rovers in 1989. Both the 13CU and 14CU were designed for use with only the 3.5L version of the Rover V8.

The 14CUX was the final iteration of the system, and featured upgraded injectors and (for some markets) an external diagnostic display. It also introduced the use of a "tune resistor", which is an external resistor that plugs into the harness and is sensed by the ECU to select one of five different sets of fueling data.

The engine control unit (ECU) of the 14CUX system is run by a Motorola MC6803U4 8-bit microprocessor, which is an uncommon variant of the otherwise ubiquitous 6803. The processor is mislabelled in the ECU, possibly to deter any reverse engineering efforts. The 14CUX determines fueling values for each bank of the V8 separately, which requires the use of two dedicated timer outputs for independent control of the fuel injectors. This requirement helped to drive the selection of the MC6803U4 part, which has three timer outputs available (in contrast to the single timer output on the standard 6803.)