OldBeaver, the diesel stuff is very interesting.
I was trying to remember everything I could from that 4 hour MPG drive.
While the MPG = f(TPS) lets reference the Throttle Position Sensor, I'm thinking there was some "2nd order" fluctuation.
In other words, for fixed TPS, the MPG would vary a "few" MPG. maybe 5%
Since this is neglible when compared to changing gears or TPS, I did not specifically mention it.
Another compensating relationship:
- Lower load => Higher Vacuum => Higher Flow past Throttle Plate => HIGHER IPW per revolution. (where IPW = Injector Pulse Width)
- Lower load => Leaner Mixture => LOWER IPW per revolution
- So there is some cancellation. (Opposite true going up hill.)
As far as controlling the cruise control, MPG = f(IPW). IPW determines the amount of fuel leaving the fuel tank per revolution.
Could this Intelligent Cruise Control be used to maintain a specific IPW and hence MPG?
Tom