Wade:
Maybe I didn't make it clear enough. The idea is to adjust it at a load point where you know there is no knock. For example, 0psi on the highway.
The reason for doing this under some (light) load is that engines make more noise when they are not loaded, such as when free revving, or in decel. The engine actually gets quieter as you load it.
Note that the unit has an onboard MAP sensor. This is for the boost retard function, plus the detector is turned off with more than 5" vacuum, to prevent false detections on decel and light loads. We recommend temporarily disconnecting the manifold line from the unit while adjusting the sensitivity. This forces the unit to see 0 psi, enabling the detector.
While cruising on the freeway, gradually increase the sensitivity until the unit just starts to detect ENGINE NOISE, then back it off slightly. This sets the unit to max sensitivity without detecting false knock. The unit will now respond to inaudible knock when you load the engine.
After setting the sensitivity, but with the vacuum line still disconnected, lift throttle, to test for false knock on decel. If there are no detections on decel, and you do not wish to use the boost retard function, you may leave the vacuum line disconnected.
If there is some false knock on decel, but you don't wish to use boost retard, connect the vacuum line but turn the boost retard "Rate" knob to zero.
Note that RPM must be above 1750 to enable the detector and any retard feature.
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