1990 MAZDA 232 Workshop Manual Suplement

F2 TURBOCHARGER CONTROL [BP TURBO]
TURBOCHARGER CONTROL [BP TURBO]
OUTLINE
l The air-to-air intercooler is adopted to lower intake air temperature and to improve engine performance.
l With addition of the wastegate control system, engine torque at higher rpm is increased.
AIR BYPASS VALVE
WASTEGATE
SOLENOID VALVE
TURBOCHAR
ACTUATOR
-
SYSTEM DIAGRAM
AIR BYPASS VALVE 1
t
!NTERCOOLER
n Ii Y7rzFes-~ m I
-
TUREiOCHARGER
WASTEGATE SOLENO1D VALVE
93GOF2-7 7
FZ-12

TURBOCHARGER CONTROL [BP TURBO] F2
WASTEGATE CONTROL
The engine control unit controls the wastegate solenoid valve to give higher boost to the engine in the higher
rpm range, increasing engine torque
and power.
System
Diagram
I
t
1 ECU
i i
AIRFLOW METER ACTUATOR
WASTEGATE
WASTEGATE
SOLENOID VALVE
r ACTUATOR
WASTEGATE SOLENOID VALVE
: OFF (VALVE CLOSED)
ACTUATOR
BOOST
PRESSURE
WASTEGATE SULENOlD VALVE
: ON (VALVE OPEN) Operation
Engine speed below 5,300 rpm
The
wastegate solenoid valve is OFF. Boost pressure is ap-
plied directly to the actuator and the wastegate opens when
the boost pressure exceeds 49 kPa (0.5 kg/cm , 7.1
psi).
Engine speed above 5,300 rpm
The wastegate
solenoid valve is UN. Some boost pressure is
bypassed to the intake manifold, limiting the opening of the
wastegate to increase boost pressure and
improve engine per-
formance.
F2-13

F2 TURBOCHARGER CONTROL [BP TURBO]
93GOF.Z721
!=2-14 LARGE
+ FULLY OPEN
BYPASS AIR
i 8EGlNNIp
AMOLIN OF OPEN
SMALIL
430 VACUUM
(5-l) mmt-lg
TURBOCHARGER OnW
INLET
lntercooler
The air-to-air intercooler utilizes fresh air flow through the in-
tercooler core to reduce the intake air temperature.
If
the air compressed by the turbocharger was sent directly
into the combustion chamber without passing through the in-
tercooler, the charging air efficiency would be
reduced by the
high temperature of the intake aii-.
The intercooler, by cooling this high temperature air, substan-
tially increases the charging air efficiency
and engine output,
as well as supressing ignition knocking by reducing the com-
bustion gas temperature.
The intercooler is mounted at
the left front of the vehicle.
Air Bypass Valve
The air bypass valve bypasses intake air from the air funnel
to before the turbocharger in order to reduce air vibration noise
during deceleration.
When the throttle valve is closed suddenly during high-rpm
and heavy-load operation, air vibration occurs between the
throttle vatve and the turbocharger as a result of pressuriza-
tion
caused by inertia of the intake air. This system prevents
such noise.

FUEL SYSTEM F2
FUEL SYSTEM
Due to the installation of the propeller shaft fur the 4WD, the fuel tank is designed with left and right section.
Therefore, a transfer pump is used to pump the fuet from the left to the right (fuel pump) side. The transfer
pump is mounted in the fuel tank, and is controlled by the transfer pump switch and the fuel pump control unit.
The fuel pump control system is adopted for BP turbo model.
CONSTRUCTION
PRESSURE REGULATOR
FUEL PUMP
FUEL PUMP
RESISTOR/REU\Y
TRANSFER PUMP
/
FUELPUM IP SWI’
TCH
FUEL VAPOR
FUEL TANK
i
4x4 CONTROL UNIT [BP SOHC]
FUEL PUMP CONTROL UNlT [BP TURBO]

F2 FUEL SYSTEM
FUEL VAPOR VALVE
FUEL VAPOR VALVE
93GOF2-722
The fuel vapor valve is installed in the fuel tank to allow fuel vapors within the tank to escape to the charcoal
canister.
The fuel vapor valve contains a shut-off valve to prevent raw fuel from escaping during hard cornering
01
at other times when there is significant fuel slosh.
FUEL PUMP CONTROL SYSTEM [BP TURBO]
Outline
l The fuel pump control system supplies electric power to the fuel pump at ail times while the engine is
running. The fuel pump can thus operate even though the fuel pump switch in the airflow meter OFF.
rhe fuel pump switch may open (switch OFF) on deceleration due to back-flow of air from the turbocharger.]
l To improve fuel pump longevity, the fuel pump is controlled by the engine control unit (ECU). (Refer to
next page.)
MAIN RELAY (FUEL 1NJ RELAY)
I I FUEL PUMP
RESISTOR/RELAY ECU
I
ON
P CIRCUIT OPENING
I--
DIAGNOSIS
CONNECTOR
TERMINAL F/P CPU
F2-16

FUEL SYSTEM F2
Two-stage WeI pump operation
Engine running (Except heavy load or cranking)
The ECU 1 I circuit is ON, opening the contact plate in the fuel pump resistor/relay. Current from the circuit
opening relay to the fuel pump flows through the resistor in the fuel pump resistor/relay, and the voltage
to the fuel pump is reduced to approx. WV, causing the fuel pump to operate at a reduced speed to im-
move fuel pump longevity.
MAIN RELAY
Engine under heavy load or cranking
The ECU 1 I circuit is OFF and the contact plate in the fuel pump resistor/relay is closed. Unreduced battery
current flows to the fuel pump through the contact plate, causing the fuel pump speed and output to be
increased to meet the demands of the engine.
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93GW2-725
FZ-17

F2 FUEL SYSTEM
93GOF2-726
FUEL PUMP RESISTOR/RELAY [BP TURBO]
The fuel pump resistorlretay supplies battery voltage to the
fuel pump when the ECU 11 circuit is OFF, and approx. 1 OV
when the ECU 11 circuit is ON. It is mounted on the firewall.
TRANSFER PUMP CONTROL
Outline
The fuel tank is buitt with separate right and left sections to accommodate the. installation of the propeller
shaft. As fuel is puited from the right side of the tank, the transfer pump pumps the fuel from the left to the
right (fuel pumb) side to balance the fuel level.
FUEL IN LEFT TANK
I
FUEL PUMP CONTROL. UNIT
/ TRANSFER PUMP
TRANSFER PUMP SWITCH: OFF
NO FUEL IN LEFT
TANK
FUEL PUMP CONTROL UNIT / TRiNSFER PUMP
TRANSFER PUMP SWITCH: UN
93GOF2-727
Operation 1. Whenever the ignition switch is ON and fuel is in the left (transfer pump)
side of the fuel tank the fuel pump switch is open, the transfer pump circuit in the fuel pump control unit is
closed, and the transfer pump
operates.
2. When the fuel in the left side of the tank drips betow a specified point, the fuel pump switch is grounded
and the transfer pump stops operation.
3. To prevent the transfer pump from
being turned ON and OFF repeatedly, possibly shorting the life of the
pump, when the vehicle is driven on a rough
road and the fuel level is low, there is a ten-second delay
circuit in the control unit to delay the turning ON and OFF the pump.
f2--I 8

FUELSYSTEM F2
Transfer Pump Switch
- -
93GOF2-726
The
fuel pump switch is a float-type ON/OFF switch used to operate the transfer pump. It is part of the fuel
gauge sender unit. ^_