I just thought of a way of monitoring and recording
 the actual mixture values of all four injectors as the engine
 goes through the RPM and power range.

 Use one of the $80 HyTec USB data acquisitions systems
 and four of Tracy's flow meter circuits. This would give
 a person a big picture overview of what exactly the EFI computer
 is doing in real time. Particularly important around the injector
 staging area at 15 inches of HG. A tremendous tuning aid.

 Each flow meter circuit would be connected to each injector wire.

 Only one 74HC04 50 cent chip would be required as there are six
 inverter circuits in each chip. A couple of pressure sensors
 can be incorporated and an opto isolator for monitoring engine
 RPM. None of these parts are very expensive.

 This would work with any EFI system not just Tracy's.

 A custom PC board with the OEM version of the HyTec DataAq
 mounted on it could be made.

 This would be a good product for some electronic
 type to build and sell. If I don't hear from somebody
 soon I may do it myself.

 Paul Lamar


The injector signal is a 12V negative going pulse.  The other side of
the injector being tied to +12V, the trigger is a open collector (or
open drain) output.

Bob W.