Variable Induction System

Using a vacuum "T", connect a vacuum gauge into vacuum line between vacuum switching valve and Toyota Variable Induction System (T-VIS) diaphragm. See Fig 1. Connect tachometer to engine. See ADJUSTMENTS article in the ENGINE PERFORMANCE Section for correct tachometer attachment.
Start engine and warm to normal operating temperature. Vacuum gauge should show high vacuum at idle (internal throttle valve closed). Increase engine speed to greater than 4000 RPM.
Vacuum gauge should indicate zero. If gauge does not indicate zero, use hand held vacuum pump to verify T-VIS diaphragm holds vacuum. If T-VIS diaphragm holds vacuum, go to next step.
Check T-VIS vacuum switching valve by removing top of intake manifold. Ensure resistance across vacuum switching valve connector terminals is 33-39 ohms. Ensure there is no continuity between wiring terminals and valve body. Check airflow through valve. See Fig 2.

Fig 1: Testing Variable Induction System (Celica Shown; MR2 Similar)

Fig 2: Testing Variable Induction System Vacuum Switching Valve