Electronic Fuel Injection System (hot wire)
Fuel tank The fuel tank is a 20-gallon unit with an expansion tank and vapor recovery system. The tank is a new Range Rover unit that is designed for fuel injection. I used the original vapor recovery tank but used the Range Rover charcoal canister and valve. I cut a hole in the bottom of the trunk for the fuel tank to go up into. The tank protrudes about 4 inches into the trunk and is not in the away
Fuel Lines The fuel lines are made of thick walled 3/8" copper tubing. I ran the main and return line parallel where the original line went.
Fuel pump The Fuel pump is a Land rover unit that is built into the Land Rover fuel tank.
Fuel Injection I used fuel injection because it was much less expensive for me to run since I already had it and knew how it worked. The System is relatively easy to understand. There are just a few parts that make the whole thing work. The air flow anemometer is what makes the system a "hot wire" fuel injected engine. A hot wire anemometer uses a very thin wire, about 12 micrometers in diameter, through which an electric current is passed. The wire is suspended buy two supports and is in contact with the moving air. The wire is heated buy an electric current and is cooled buy heat transfer to the moving air. The amount of cooling depends on the velocity of the air. So a variation in the air flow causes a change in the wire temperature, and therefore its resistance changes. The electronic measurement of the resistance change can be related to the flow velocity. This is used to calculate the fuel to air ratio. This is computed with several other sensors, temperature, O2, speed, to make the correct measure of fuel into the combustion chamber. This system is much more efficient that a carburetor and is maintenance free!
Fuel Injector Swap The 1989 3.9L engine I used had the early style fuel injectors. I was able to purchase a set of the new style fuel infectors at a good price so I decided to upgrade. The 1990-95 injectors use an entirely new design that help to produce more power and efficiency. After installing these injectors I was able to squeal tires in 1st, 2nd, and 3rd. I also was able to reach my efficiency goal of 28 MPG.
Speed Sensor The Speed sensor is an important part of the EFI system. It tells the engine if the vehicle is in motion or about to come to idle. Without this sensor in place the engine will idle less smoothly and stall at times after coming to a stop after a high speed drive. In my MGV8 I have an electronic speedometer that has no cable drive from the transmission. Therefore I had no way to easily add the speed sensor in the original inline location. I dismantled the speed transducer and encapsulated the wafer in silicon. Then I mounted the sensor on a bracket and fixed a magnet to the drive shaft and positioned the sensor so that it just cleared the shaft. This worked great and It is important to run the speed sensor. The ECU runs much smother when it gets speed feedback.
14CU To 14CUX Electronic Control Unit Swap From the beginning I wanted to use the post 1990 14CUX ECU with the fault display. I had bought a 1989 Range Rover for the engine and electronics because if its availability thinking I could upgrade later on; Well I have.
There are a few differences between the US Only 14 CU and the Universal 14CUX. The main differences are an external Select Tune Resistor, and a fault code display as well as being better quality and more refined. The sensors on the engine stayed the same, with the exception of more efficient fuel injectors added in 1990 with a gain of One MPG. The tune select resistor was utilized so one ECU could be used in all locations. There were several different tune select resistors depending on the location.
Red wire, 180 Ohms, Australia, Rest of world.
Green wire, 470 Ohms, UK and Europe - Non Catalyst
Yellow wire, 910 Ohms, Saudi - Non Catalyst
White wire, 3900 Ohms, USA and Europe - Catalyst
The computer swap was fairly strait forward. I had to add three pins to the 40 pin multi plug of the original 1989 Range Rover harness. I had a spare harness and salvaged the pins from it. The pins missing were 30 (Pink), 31 (Black/Green), and 38 (Brown/Pink). Pin 37 (White/Yellow) is not used with the 14CUX. These new pins/wires are used to wire the fault display and the tune select resistor. Pin 5 (Black/White) runs to the tune select resistor and can be found at the Blue (Heater A/C) multi plug in your EFI harness. The other end of the TS Resistor is spliced into pin 27 (Black/Grey) along with the corresponding color wire in the fault display. Pin 30 (Pink), 38 (Brown/Pink), and 2 (Brown/Orange) are run to the corresponding color wire in the fault display. Pin 18 (White/Pink) is connected directly to 27 (Black/Grey) and 31 (Black/Green) or can be rewired as shown in the 1990 schematic below to except the Rover dealer's old diagnostic system, if they still have one. That is all it takes :)
I have noticed a smother idle and the engine runs leaner with the 470 Ohm resistor. There is a misnomer that using a 470 Ohm resistor nullifies the O2 sensors and this is not true. The O2 sensors still send information to the ECU to compare the burned fuel mixture and rectify if necessary.
The photos below are of the 1990-1994-5 14CUX and to the right the 1989 14CU
