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Supercharger (4A-GZE) System Outline
Submitted By Roger S. Prior
This outline covers only the operation of the supercharger system. For details
on the entire TCCS system, please refer to the TCCS System Outline.
1.
SUPERCHARGER
CONTROL SYSTEM
(a)
Supercharger
magnet clutch operation
The engine revolutions are monitored by means of the
signals from each sensor (RPM signal system, Throttle signal system, STA
(starting) signal system) input to the ECU. Based on this data and the program
recorded in the ECU memory, current is output on terminal SMC of the ECU and the
supercharger relay is controlled.
(b)
VSV (air
control valve, air bypass valve) operation
The air bypass valve comes on when the air is
supercharged above a fixed pressure and goes off when the pressure falls below a
certain pressure, thus controlling the supercharged pressure. The air control
valve prevents grease and oil from flowing into the housing when the
supercharger is operating. The ECU evaluates the signals from each sensor (Water
temperature signal system, RPM signal system, Intake air volume signal system,
STA (starting) signal system), current is output to terminals VSV2 and VSV3, and
controls each valve.
(c)
Supercharger
indicator light operation
When the ECU judges from the signals from each sensor
(RPM signal system, Intake air volume signal system) that the intake air volume
exceeds approximately 600cc per engine revolution, current is output to terminal
TIL of the ECU, causing the indicator light to light up.
2.
SIGNAL
SYSTEMS
(a)
Intake
air volume signal system
Intake air volume is detected by the potentiometer
installed inside the air flow meter and is input as a control signal to terminal
VS of the ECU. Inside the air flow meter there is also a switch for fuel pump
operation, and when the measuring plate opens (air intake occurs), this switch
turns on and current flows to the fuel pump to operate it.
(b)
RPM
signal system
Crankshaft position and engine rpm are detected by
the pick-up coil installed inside the distributor. Crankshaft position is input
as a control signal to terminal G1 and G2 of the ECU, and rpm is input to
terminal NE.
(c)
STA
signal system
To confirm that the engine is cranking, the voltage
applied to the starter motor during cranking is detected and is input as a
control signal to terminal STA of the ECU.
(d)
Throttle
signal system
The throttle position sensor detects the throttle
valve opening angle, which is input as a control signal to terminal VTA of the
ECU, or when the valve is fully closed, to terminal IDL.
(e)
Water
temperature signal system
The water temperature sensor detects the e/g
coolant temperature and has a built-in thermistor with a resistance which varies
according to the water temperature thus the water temperature is input in the
form of a control signal to terminal THW of the TCCS ECU.
The TCCS system utilizes a microcomputer and
maintains overall control of the engine, timing, etc. An outline of engine
control is given here.
1. INPUT SIGNALS
Water temperature signal system
The water temperature sensor detects the engine
coolant temperature and has a built-in thermistor with a resistance which
varies according to the water temperature thus the water temperature is input
in the form of a control signal to terminal THW of the TCCS ECU.
Intake air temperature signal system
The intake air temperature sensor is installed
inside the air flow meter and detects the intake air temperature, which is
input as a control signal to terminal THA of the ECU.
OX sensor signal system
The oxygen density in the exhaust emissions is
detected and input as a control signal to terminal OX of the ECU. To maintain
stable detection performance by the OX sensor, a heater is used for warming
the sensor. The heater is also controlled by the ECU (HT).
RPM signal system
Crankshaft position and engine rpm are detected
by the pick-up coil installed inside the distributor. Crankshaft position is
input as a control signal to terminal G+ (4A-GE), or G1 and G2 (4A-GZE), of
the ECU, and rpm is input to terminal NE.
Throttle signal system
The throttle position sensor detects the
throttle valve opening angle, which is input as a control signal to terminal
VTA of the ECU, or when the valve is fully closed, to terminal IDL.
Vehicle speed signal system
The speed sensor, installed inside the
combination meter, detects the vehicle speed and inputs a control signal to
terminal SPD of the ECU.
Neutral start switch signal system
The neutral start switch detects whether the
shift position is in neutral or not, and inputs a control signal to terminal
NSW of the ECU.
A/C switch signal system
The operating voltage of the a/c magnet clutch
is detected and input in the form of a control signal to terminal A/C of the
ECU.
Battery signal system
Voltage is constantly applied to terminal BATT
of the ECU. When the ignition switch is turned to on, voltage for ECU
operation is applied via the EFI main relay to terminals +B and B1 of the ECU.
Intake air volume signal system
Intake air volume is detected by the
potentiometer installed inside the air flow meter and is input as a control
signal to terminal VS of the ECU. Inside the air flow meter there is also a
switch for fuel pump operation, and when the measuring plate opens (air intake
occurs), this switch turns on and current flows to the fuel pump to operate
it.
Stop light switch signal system
The stop light switch is used to detect whether
or not the vehicle is braking and the information is input as a control signal
to terminal STP (4A-GE) or ELS1 (4A-GZE) of the ECU.
STA signal system
To confirm that the engine is cranking, the
voltage applied to the starter motor during cranking is detected and is input
as a control signal to terminal STA of the ECU.
Engine knock signal system (4A-GZE)
Engine knocking is detected by the knock sensor
and input as a control signal to terminal KNK of the ECU.
Fuel control signal system (4A-GZE)
The type of gasoline being used (regular of
premium) is judged by the fuel control switch and is input as a control signal
to terminal R/P of the ECU.
Electrical idle-up system (4A-GZE)
The signal, when systems such as the rear
window defogger, headlights, etc, which cause a high electrical burden are on,
is input to terminal ELS2 as a control signal.
2. CONTROL SYSTEM
EFI (electronic fuel injection) system
The EFI system monitors the engine revolutions
through the signals each sensor (input signals a to l) input to the ECU. Based
on this data and the program memorized in the ECU, the most appropriate fuel
injection timing is decided and current is output to terminals #10 and #20 of
the ECU, causing the injectors to operate (to inject fuel). It is this system
which through the work of the ECU finely controls fuel injection in response
to driving conditions.
ESA (electronic spark advance) system
The ESA system monitors the engine revolutions
using the signals (input signals a, c to h, j, m, n) input to the ECU from
each sensor. Based on this data and the program memorized in the ECU, the most
appropriate ignition timing is decided and current is output to terminal IGT
of the ECU. This output controls the igniter to pressure the most appropriate
ignition timing for the driving conditions.
Fuel pressure-up system
The fuel pressure up system causes the VSV (for
fuel pressure up) to come on for high temperature starts and for about 90
seconds after starting in order to increase the fuel pressure, improve
startability at high temperatures and provide stable idling. The ECU evaluates
the input signals from each sensor (a and b for 4A-GE, a, b, d, and l for
4A-GZE), outputs current to terminal FPU and controls the VSV.
OX sensor heater control system
The OX sensor heater control system turns the
heater to on when the intake air volume is low (temperature of exhaust
emissions low), and warms up the OX sensor to improve detection performance of
the sensor. The ECU evaluates the signals from each sensor (input signals a,
f, i, j, l), current is output to terminal HT and controls the heater.
Idle-up system (4A-GE}
The idle-up system uses the VSV for electrical
idle-up to increase the rpm and provide stable idling when the idle speed
drops due to the electrical load, etc. The ECU evaluates the signals from each
sensor (input signals a, d to h, k). Current is output to terminal V-ISC and
controls the VSV.
ISC (idle speed control) system (4A-GZE)
The ISC system (rotary solenoid type) increases
the rpm and provides idling stability for fast idle-up when the engine is
cold. When the idle speed has dropped due to electrical load, etc. the ECU
evaluates the signals from each sensor (input signals a, d to h, k, l, o),
outputs current to terminals RSC and RSO, and controls the ISC valve.
Intake air control system (4A-GE)
In the intake air control system, each cylinder
in the intake manifold is divided into two parts, with an intake air control
valve installed in the passage on one side. The opening and closing of this
valve provides the most appropriate intake airflow and, as well as preventing
performance loss at low speeds, also improves fuel economy. The ECU evaluates
the signals from each sensor (input signals a, d, e), outputs current to
terminal S/TH, controls the VSV (for T-VIS) and, carries out opening and
closing of the valve.
Supercharger control system (4A-GZE)
Supercharger magnet clutch operation
The engine revolutions are monitored by means
of the signals from each sensor (input signals d, e, l) input to the ECU.
Based on this data and the program recorded in the ECU memory, current is
output on terminal SMC of the ECU and the supercharger relay is controlled.
VSV (air control valve, air bypass valve)
operation
The air bypass valve comes on when the air is
supercharged above a fixed pressure and goes off when the pressure falls
below a certain pressure, thus controlling the supercharged pressure. The
air control valve prevents grease and oil from flowing into the housing when
the supercharger is operating. The ECU evaluates the signals from each
sensor (input signals a, d, j, l), current is output to terminals VSV2 and
VSV3, and controls each valve.
Supercharger indicator light operation
When the ECU judges from the signals from
each sensor (input signals d, j) that the intake air volume exceeds
approximately 600cc per engine revolution, current is output to terminal TIL
of the ECU, causing the indicator light to light up.
EGR control system
With the EGR control system, the ECU evaluates
the (input signals a, d, j) from each sensor, current is output to terminal
EGR and operation of the EGR valve is controlled.
3. DIAGNOSIS SYSTEM
With the diagnosis system, when there is a
malfunction in the ECU signal system, the malfunctioning system is recorded in
the memory. The malfunctioning system can then be found by reading the display
(code) of the check engine warning light.
4. FAIL-SAFE SYSTEM
When a malfunction occurs in any system, if
there is a possibility of engine trouble being caused by continued control
based on the signals from that system, the fail-safe system either controls
the system by using data (standard values) recorded in the ECU memory or else
stops the engine.
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