Megasquirt Plug & Play Fitting Instructions

This is fast becoming the best and easiest engine upgrade for the Rover V8 engine. For many years the biggest restriction to performance upgrades for the engine has been the re-mapping of the engine to make the most of the performance enhancements that can be fitted. There have obviously been many aftermarket injection systems available but all of them have required the removal of the existing wiring loom and ancillaries and the installation of a completely new system and all of its associated issues. With this in mind, V8Developments and Extra EFi have come up with what we feel is a very neat and simple solution. Extra Efi have put the Megasquirt fuel injection system into a new housing that incorporates an original 14CUX wiring loom connector. The functionality of the ECU has then been matched through the wiring connections that already exist in the car so that it is not necessary to change the loom. An air temperature sensor is added to the loom (a simple plug in connection) and a resistor removed, again very simple and the system is ready to run.

There are a number of options available, from a simple replacement ECU to a full replacement system, including mapped ignition, crank position sensors and new wiring looms. Choices are generally made on the basis of vehicle, required performance and current equipment but advice is available for anyone wishing to investigate the possibilities.

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Plug 'n' Play - Fuel Only

The ECU replacement is extremely simple.

Identify the RPM feed to the Lucas ECU.


There are two resistors (usually taped to the outside of the loom near the coil) with either white / blue or white / black wires. Remove one of the resistors and leave the ends isolated. Try to start the car as you normally would. If the engine starts and the rev counter does not work, you have removed the wrong resistor, replace it and remove the other one. If the engine refuses to start, you have the correct resistor, replace the resistor with the supplied connection.

Locate the Fuel Temperature Sensor (this on either the passenger side, attached to the fuel rail, or at the front of the engine, just behind the alternator)

Temperature sensor

Disconnect the loom connector.

Loom connector

Connect the supplied air temperature sensor into the loom side of the sensors connector. Mount the air temperature sensor somewhere in the air flow into the engine (ideally fairly close to the throttle butterfly).

Disconnect the 14CUX ECU.


Connect the V8D / Extra EFi Megasquirt P&P ECU.

Megasquirt ECU

Connect a PC or Laptop to the supplied Comms lead and then to the Extra EFi ECU.
Install the supplied software (Tuner studio is best)
Run the software (If using Windows Vista Run as Administrator).


Turn on the ignition, do not try to fire the engine at this point.

Select "Tools >> Calibrate TPS" from the menu and follow the instructions.

Software menu

Select "Close" when finished.

Attempt to start the engine.

At this point it must be noted that the supplied 'map' is a starting point only! Every car and engine is unique and we do not suggest that the fuelling will be correct to run the engine. At this point in the procedure it is essential that some form of emissions tester (gas analyser, lambda sensor etc.) is connected and reading the exhaust output.
Fuel mapping and alterations to idle speed etc. can now be made to ensure the engine is performing optimally in all conditions. Further instructions on the setup and fuelling alterations can be found on the Megasquirt & Tuner Studio main websites.