ecu voltage problem

[S. Lastuka]

The ECU voltage problem has been remedied.  We stayed up till 6:30am
figuring it out.  

The problem was that our batch fire injection system draws a lot of
current everytime the injectors fire.  In fact it draws so much that
battery voltage was dropping and resetting the computer. 

We found that our ground traces on the board were very small for the type
of current (2 amp peaks) that flows from the injectors to ground on each
fire. So we simply wired up some heavy guage wire to every high current
section of the injector circuit, especially our grounds.  We took the
revised board back out to the car and it started right up with absolutely
no resetting after injector fire.

  My theory is that the circuitry that originally was wiring up the injector
driver circuits was so puny that there was a voltage drop across the
ground traces and this was directly causing the computer to "see" a lesser
supply voltage.  
I guess that is part of the learning process and I have a much greater
respect for grounds that they don't teach you in the classroom.  

I would like to thank everyone for their suggestions and assistance, and
good luck with your projects in the future.

Sean
University of Washington
Dept. of Electrical Engineering
Formula SAE