I can personally vouch that the Cyberdyne gauge can be used concurrently with an engine management system. As a matter of fact, Cyberdyne's instructions which come with the gauge sort of expect this type of installation. All O2 sensors are universal... so far as their output goes. So the Cyberdyne gauge will work with anything you got from Holley or anyone else.

In trying to track down a problem on my 1987 Subaru GL-10 Turbo wagon, for a period of time I moved the Cyberdyne mixture gauge over to it (it's back in the Scout now). All I did was remove a small amount of insulation from the output wire of the existing O2 sensor in the Subaru and solder on a small gauge wire running to the Cyberdyne gauge. I covered the connection with heat shrink tubing. That's all there is to it!

It worked great in the Subaru as well as the Scout. I could watch the mixture start out rich when the coolant temp was cold. Then, when the closed-loop mode kicked in, the mixture would continuously and rapidly bounce up and down around the stoichiometric mixture as the computer kept adjusting and hunting for the perfect mixture. The faster the engine would run, the faster the bouncing of the LED's. It was really cool to watch when driving at night. As the accelerator is pushed nearly to, or all the way to the floor, an open-loop enrichment mode would activate and the gauge would instantly show very rich. Likewise, releasing the accelerator pedal during deceleration shuts off the fuel injectors completely (in this particular car) and the gauge would instantly show the mixture so lean the gauge would be blank.

The gauge in no way affected the operation of the engine management computer or the output of the O2 sensor. I suspect the gauge consumes an almost undetectable amount of current from the O2 sensor. So for the less than $40.00 the Cyberdyne gauge costs, I'd definitely install one if I had a Projection system.

Both Summit Racing (www.summitracing.com) and Jegs (www.jegs.com) carry it.

Regards,

John Landry