Over the past 16 years we must have spent thousands of hours trying
to trouble shoot Tracy's EFI system with out adequate information.
On production cars this problem is solved with OBD II. OBD stands for
on board diagnostics and was mandated by the gov. OBD II sends error
codes to a connector under the dash board. This can be connected to a
PC with the proper cable. This is a very effective system and can be
diagnosed in seconds.
A maximite could do the same thing by displaying data from the
sensors and the pulse width of the injectors on a small VGA while it
was running the EFI.
My plate is full with the newsletter, my new ignition system, the TTC
project and up grading my NC mill. I have a small amount of time to
help if somebody would be kind enough take over this project. You
would be gaining a very valuable skill.
Paul Lamar
This sounds like a fascinating project. I've been looking for local
folks with racing/EFI/computer experience who might be willing to
assist. No luck so far, but I will keep looking. Might have another
good contact this weekend. It is clearly out of the scope of my
individual talents!
Scott Gettings
You under estimate your self Scott. I know you better than that. It
should not take long.
Paul Lamar
Here is another point. The Maximite and DOS/QB hardware control
development systems are the only hardware control development
systems where you do not have to build the actually target hardware
to test them.
All output and control data, normally going to control hardware, is
merely printed on the screen or saved in a text file along with the
sensor date that caused them to happen.
For an EFI system you can simulate the manifold pressure sensor with
a potentiometer. The top of the pot is connected to 5 volts and the
bottom is grounded. The wiper is connected to an Analog to Digital
pin on the Maximite. You are now ready to start programming.
You can add a RPM input with a variable oscillator. Or a variable
speed drill motor revolving a short piece of steel and a stock crank
angle sensor.
Here are some pictures.
Paul Lamar
It started with OBD1. This worked fairly well for diagnostics.
However the fly in the ointment was that each manufacturer
was doing the codes and software different. Then Europe and
Japan had their own deal happening. In a dealership where
you only dealt with one manufacture it was not a problem. The
independent shops had big trouble. Of course the manufacturers
did not want to share information. That is when the US government
mandated the OBD2 standard. Now the codes are standardized.
Cylinder 3 misfire code is the same. Then you just need to
determine what the exact cause is for the error. That is of
course the trick.
Dale Davies
Everybody interested in EFI and particularly everybody with Tracy's
system should get OBD II for their car. It will give you a profound
understanding of what is going on in real time as it is working.
Paul Lamar
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