System Operation

When engine RPM is less than 3200 RPM, a PCM signal activates IAB low and high control solenoid valves allowing vacuum to IAB control low and high diaphragms. When vacuum is applied to low and high diaphragm valves, IAB control valves inside manifold close. This causes a long intake air path increasing low RPM torque.

When engine speed is 3200-3800 RPM, PCM deactivates IAB control low solenoid valve, cutting vacuum to IAB control low diaphragm valve. This causes intake air to go through a medium intake air path, increasing mid-range RPM torque.

When engine speeds are greater than 3800 RPM, PCM deactivates both IAB control low and high solenoid valves. This causes intake air to go through a short path, increasing high-speed RPM torque. A malfunction in IAB control system will cause a low engine power condition.