Variable Dynamic Effect Intake (VDI) System

VALVE AND ACTUATOR CHECKING

VDI System Manifold Assembly:

1. Check for vacuum leaks at VDI valve cover plate and shaft. If leaks are present, re-seal mating surfaces or replace valve assembly as necessary.

Actuator Testing:

2. Disconnect air pressure hose to VDI valve actuator, and connect vacuum/pressure gauge as shown in diagram.

3. Apply air pressure regulated to 2.8 psi (2.0 kPa) to actuator.

^ Check that actuator rotates VDI valve to fully open position (valve rotates approx. 90° from the closed position stop to the open position stop) with the prescribed air pressure applied to actuator.

CAUTION: DO NOT INCREASE AIR PRESSURE. Valve and actuator should operate at the prescribed air pressure. Applying higher pressure may damage actuator diaphragm.

VDI Valve:

If actuator does not move valve when air pressure is applied, remove actuator and operate valve manually to check for sticking. If valve is sticking, remove it and check for carbon deposits, corrosion, or damage. Clean/lubricate, repair or replace valve as necessary.

4. While air pressure is applied, pinch air hose closed at actuator port and remove air pressure supply. Keep hose pinched closed while watching actuator rod.

^ Actuator diaphragm should hold pressure without leaking down. If actuator rod retracts, closing valve, then diaphragm is leaking and actuator should be replaced.

SOLENOID VALVE CHECK

1. Disconnect hoses from solenoid valve and remove valve.

Solenoid Valve -- No Voltage Applied:

2. Blow through valve from port "B".

^ Air should flow through valve from "B" to the filtered vent.

Solenoid Valve -- Voltage Applied:

2. Apply battery power and ground to the solenoid, and blow through valve again from port "B".

^ Air should flow through valve from "B" to "A", and vent should be closed.

If solenoid valve does not operate as described, replace it.

CONTROL SIGNAL (SOLENOID VALVE)

The control signal can only be checked on a road test or dynamometer test. The solenoid valve receives battery power, from the main relay, when the ignition is turned "ON". The solenoid is energized when the ECU completes the circuit to ground. The ECU should complete the circuit to ground when the engine is under heavy load or acceleration (full throttle), and the engine speed is greater than approx. 5,200 rpm.

1. With the solenoid connected, back probe the connector with a long jumper wire (long enough to reach the passenger seat) to the Yellow/Black wire terminal of the VDI solenoid valve (Be sure connection is secure and wire is not pinched when closing the hood).

2. Test drive the car, accelerating hard in a middle gear up to approx. 5,500 rpm, while monitoring the voltage of the jumper wire.

^ Should have charging system voltage until the engine speed reaches 5,200 rpm. Above this speed, voltage should drop to zero or nearly zero.

If voltage is not as described, check wiring between main relay and solenoid valve for open. Also, check wiring between solenoid valve and ECU terminal 2M for open or short to ground.

If voltage is correct below 5,200 rpm but does not change above that engine speed, either there is an open circuit between the solenoid and the ECU, or the ECU is not completing the circuit to ground when it should (faulty throttle sensor or wiring, no engine speed signal to the ECU, or faulty ECU).

NOTE: This test can also be performed by measuring the voltage directly, at ECU terminal 2M, instead of using a jumper wire.