Ford Probe VRIS Switching Valve Diagram - Torque vs RPM Intake Operation

This schematic illustrates the operation of a Variable Resonance Induction System (VRIS) intake manifold with two switching valves (A and B). The top portion shows a cutaway drawing of the intake manifold identifying the locations of Switching valve A and Switching valve B. The main graph plots engine torque versus engine speed (rpm) for three valve configurations: curve ① with both valves closed, curve ② with valve A open and valve B closed, and curve ③ with both valves open. Each configuration produces a torque peak at a different engine speed range, and the system switches valve states as rpm rises (both closed at low rpm, A open at mid rpm, both open at higher rpm, then both closed again at the top) so the engine follows the highest available torque curve. Timelines beneath the graph show the open/closed state of valves A and B across the rpm range. A red annotation added by the uploader highlights the gap between torque curves in the mid-rpm range, labeled 'Substantial loss from non-functional VRIS,' indicating how much torque is lost if the switching valves fail to operate. No year, make, model, or part numbers are stated in the document itself.