Fuel injector pulse width monitor

Here is a picture of the faceplate that holds the LED bargraphs for air/fuel and pulse width as well as the pot to control the fuel mixture above 7psi boost.

The heart of the circuit is the transistor current source which charges cap C10 to form an integrator.  The theory is that the cap is charged and the voltage across it increases linearly for the amount of time that the injector is energized.  As the injector is switched off the voltage in C10  is stored in cap C9 and then C10 is reset to 0 volts to get ready for the next cycle.  The output of the circuit is the voltage across cap C9, this voltage is fed directly into U3 the bar graph chip to be displayed as a value between 1-10 on the LEDs.  Potentiometer R31 sets the charge rate on C10 and basically sets the max injector on time that can be displayed.