Engine Electronics
     

    The Engine Management System is based on the Lucas type 14CUX ECU, as fitted to Range Rovers in the early 1990s. That system used a hotwire airflow meter to provide the main parameter for fuel control. However, this system uses a control strategy written almost totally in-house, and has been adapted to use instead a direct reading of throttle position (known in the trade as an 'n-alpha' system - no idea why!), which when cross-referenced to engine speed can be used to address a two-dimensional map of fuelling requirements for those conditions. Advantages of this approach include freedom from intake tract restrictions and general simplicity, which is why it tended to be used for racing applications. Disadvantages are lack of adaptability (any slight change of engine spec. requires a recalibration - even changing exhaust systems or intake filter!) and lack of compensation for engine wear even in an engine of constant specification. For this reason, strategies were added for the use of oxygen ('lambda') sensors in the exhaust system to provide a degree of feedback of mixture conditions, and therefore some adaptability. Results so far are very encouraging.

     
    		 This is the actual ECU from the car. Experienced observers will notice an additional daughterboard attached to the main board. Perhaps a better view can be gained from this photo. More of that next... 
    A further consideration was that this particular ECU family was not designed to deal with ignition timing, that being left to the old-fashioned spinning weights  and vacuum diaphragms of the past several decades. Consequently, after a little design and production exercise, a daughterboard was added which plugged in where the program EPROM chip belonged and included extra electronics to perform this function. Minor modifications to the control strategy gave an ignition timing map of similar kind to the one used for fuelling. An estimated 15-20BHP has been gained by the use of the mapped ignition and the n-alpha strategy together. (Not really a lot in 300+, but it all helps!)

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