I removed my Variable resistor and checked it per FSM instructions, even attempted to adjust it to see if it functions. It did not, so I went to the local electronics store and picked up a similiar rated Variable Resistor. Soldered it up to the original plug and tested--works perfectly (I assume since i didn't have a sweep comparison to a working mazda unit).

I went out and installed it out on the car, warmed up the car. Shut down the car, installed the jumper on the appropriate plug. Restarted the Car and attempted to adjust the idle richness. Nothing happened. No variation in the idle, nothing. What could be causing the inability to adjust the idle richness with a working VR?

For those curious it's this one: Variable Resistor

Will anyone check the variable resistor to see how the sweep works (IE does one sweep go one way when leaning out the mixture and the other sweeps the opposite)?

I'm about 90% sure I wired it up correctly, which makes me wonder if my jumper or the connective pieces aren't doing the job they should be. Any ideas?

The output should vary from approx one to five volts dc. In the middle something like 2.5vdc. Something like that. I never looked at the lower and upper figures.

You don't have to jumper anything for the variable resistor to effect the Idle mixture. And it would have to be IDLE when you mess with it. Not a raging 1000 rpm bs figure.

Just look at the output of the variable resistor while you turn it, to see if it's working or not.