[mike100]

Originally Posted by Paul Workman

Really interesting setup Mike!

I think I have the jist of what you've done, but pls allow me summarize what I think I understand, and then maybe you can clear up where I "lost your trail".

The adjustable vacuum switch receives vacuum from the "T" connection that also feeds vacuum to the MAP (under the ECM on a 1900 Z). At or below 12" Hg, the switch closes, activating the vacuum solenoid.

Normally, this solenoid connects plenum vacuum to the NPPs - keeping them closed. But, when plenum vacuum drops below 12" Hg, the vacuum solenoid receives its signal and "vents" the vacuum to the atmosphere (through the foam filter), thus relaxing the NPP diaphragms and thus opening the exhaust gates.

Now, if not already, is where I get a little...

You referenced a second MAP, and dedicated vacuum solenoids for each NPP valve. I get the reasoning for the dual system - decreasing bleed time - but I'm missing a link here...

It looks like the vacuum solenoid (pictured) would directly operate the NPPs. But, it is this additional MAP you mentioned, and the electric/vacuum circuitry at the NPP end that has me . I gather the system as it is now is a "work in progress", is it? By that, I mean the NPP end of the setup is yet to be upgraded for individual operation???

As you can see, Mike, I wandered off the path somewhere...

Ok, there is some reference to the 2nd MAP sensor- that was meant for another non-ZR-1 forum where people aren't aware of the function of our vacuum secondaries (for those of us who still run them anyways).

To clarify, manifold vacuum closes the muffler flap- they are open at rest.

-To have run the valve straight from the secondary pump would have had the logic 180 reversed- plus they draw too much air and would have messed up the function probably.

So what I did was use the normally open contacts on that adjustable vacuum switch that triggers another vacuum source (through a GM EGR solenoid) when the secondary activates. What it actually does is release the actuator vacuum to the vent(when u step on it) as the solenoid is allowing vacuum through in the off condition (during cruise conditions). It is sort of reverse logic.

The vacuum source is NOT plenum vacuum. it is an is a check-valve isolated source (the vacuum ball under the d/s headlamp.