14CUX = hot wire Mass Airflow Meter
Flapper = moving flap air flow meter
Here ya go, this guy puts it in some detail:
BACKGROUND INFORMATION
The Lucas/Hitachi hot-wire MAF sensor was used on Range Rovers from their introduction in the US market in 1987.
Range Rovers built for other world markets (to 1990), Rover SD1 cars, and non-carbureted Triumph TR8 cars featured an entirely different and more primative sensor technology. Specifically, they used the Bosch L-Jetronic (L for "luft") "moving flap" air flow meter in which the moving current of induction air pushes past a spring-loaded vane. The Bosch L-Jetronic sensor dates back to about 1974. Some of the mechanical parts of these systems may be interesting to engine swappers, but the sensor and Lucas's analog electronic control system generally aren't.
The Lucas/Hitachi hot-wire MAF sensor was used with three different generations of Electronic Control Unit. With each generation the control system's electronic hardware and its programming improved, so the final version is preferable. The final version of Lucas electronic fuel injection was called "14CUX". 14CUX system were installed from 1990 through 1995 on engines with displacements of 3.9 and 4.2 liters.
The 14CUX's immediate predecessor was called 14CU. This system was used on US-market 1989 Range Rovers with 3.9L engines. It's largely similar to the 14CUX system, but the 14CUX provided several new features. Most notably, the 14CUX system included an auxiliary module to assist troubleshooting by displaying numeric fault codes (as shown below). Also, the 14CUX system came with a newer generation of Bosch fuel injectors which provide more power and approximately one mile per gallon better fuel economy. (The newer injectors are easy to retrofit to 13CU and 14CU systems.)
What came before the 14CU system? U.S. (and Swiss) market 1987 and 1988 Range Rovers with 3.5L engines came with a system called 13CU. The 13CU computer is easy to differentiate from later computers because the housing is quite different. Just look for pop-rivets.
One of the coolest things about the Rover 14CUX system is that it will self-adapt to many of our cars. For example, it will work fine with a wide range of compression ratios and exhaust systems. There are a couple notable exceptions. For example, the 14CUX system has a hard time adapting to a cam with a lobe separation angle under 112 degrees.
From this web page: HERE
Jon

