So what did we want improved in the real-time engine management tune - that is, what didn’t we like about the generic chip?

   1.      Fuel continued to be injected on the over-run. This could be seen on the instantaneous fuel consumption display (instead of going to zero it stayed at numbers as high as 8 litres/100). We wanted as little over-run fuelling as possible.

   2.      The car was slightly jerky on trailing throttle and we wanted this trait reduced or eliminated.

   3.      With the off-the-shelf chip installed, we never heard the engine detonate even the slightest, implying that the ignition timing could probably be advanced throughout the load range. (That’s not surprising, since by now 98 octane was the fuel of choice.) 

   4.      The car ran sweetly in 100 km/h cruise with air/fuel ratio of 17:1. This implied that this air/fuel ratio could be more broadly used in cruise applications.

   5.      Finally, by definition, a generic chip isn’t fine-tuned to the specific car, so we wanted that done as well.

Rob Stewart did the tune. Areas tuned included the neutral and in-gear dashpot (ie how quickly revs fall when the throttle is closed), about four different ignition maps, closed and open loop fuel maps, lean cruise fuel maps and over-run fuelling maps.