Hot Start Assist System Mazda RX-7 FC

DESCRIPTION

The hot start assist system operates the By-Pass Air Control (BAC) valve during hot starts to optimize air/fuel mixture. System consists of pressure regulator control solenoid valve and intake air temperature sensor located in intake pipe (turbo) or dynamic chamber (non-turbo).

Scheme 28

Scheme 29

1. Operate engine to warm temperature. Turn engine off. On turbo models, remove intercooler. On all models, disconnect intake air temperature sensor.
2. Install resistor at temperature sensor terminals. On non-turbo models, install 2000-3000-ohm resistor or 3500-ohm resistor on turbo models. (Scheme 28)
3. Install tachometer. Start engine and note engine RPM. Engine RPM must be at specified RPM for proper amount of time and then decrease. See ENGINE RPM SPECIFICATIONS table.
4. Shut engine off. On non-turbo models, disconnect pressure regulator hose. (Scheme 29) Place finger over end of vacuum hose. Start engine. Check that no vacuum exists for 90 seconds after engine is started and then exists after 90 seconds.
5. On turbo models, connect voltmeter to pressure regulator control solenoid valve. (Scheme 30) Start engine and note voltage. Voltage should be below 2 volts for 50 seconds after engine is started, then increase to approximately 12 volts after 50 seconds.

Scheme 30

PRESSURE REGULATOR CONTROL SOLENOID VALVE

1. Disconnect hose from solenoid. Blow through port "A". (Scheme 31) Air should flow from port "B". Remove connector from valve.
2. Apply battery voltage and ground to proper terminals. (Scheme 31) Blow through port "A". Air should flow through air filter.

Scheme 31

INTAKE AIR TEMPERATURE SENSOR

Remove sensor from dynamic chamber (non-turbo) or inlet air pipe (turbo). Using ohmmeter, measure sensor terminal resistance at specified temperature. See INTAKE AIR TEMPERATURE SENSOR RESISTANCE table. Replace sensor if not within specification.

INTAKE AIR TEMPERATURE SENSOR RESISTANCE

ENGINE RPM

ENGINE RPM SPECIFICATIONS