temperature MAZDA 626 1987 Repair Manual

4C FUEL SYSTEM
COMPONENT DESCRIPTION
Component Function Remark
Air flow sensor Detects amount of intake air;
sends signal to engine control unit
Clutch switch Detects in-gear condition; sends signal to engine control unit Switch ON when clutch pedal released
Engine control unit Detects signals from input sensors and switches; controls injector and fuel pump operations
Fuel filter Filters fuel
Fuel pump Provides fuel to injectors • Operates while engine running
• Installed in fuel tank
Fuel pump control unit (4WS) Monitors fuel level in left section; controls transfer pump operation
G signal pick-up Detects No.1 cylinder TDC; sends signal to engine control unit Installed in distributor
Idle switch Detects when throttle valve fully closed; sends signal to engine control unit Installed on throttle body
Ignition switch (ST position) Sends engine cranking signal to engine control unit
Injector Injects fuel into intake port • Controlled by signals from engine control unit • High-ohmic injector
Intake air thermo sensor Detects intake air temperature; send signal to engine control unit
Control relay Supplies electric current to injectors fuel pump and engine control unit
Ne signal pick-up Detects crank angle at 180° intervals; sends signal to engine control unit Installed in distributor
Neutral switch Detects in-gear condition; sends signal to engine control unit
Switch ON when in gear
Oxygen sensor (Unleaded fuel) Detects oxygen concentration; sends signal to engine control unit
• Zirconia ceramic and platinum coating • Integrated heater coil
Pressure regulator Adjusts fuel pressure supplied to injectors
Pulsation damper Absorbs fuel pulsation
Throttle sensor Detects throttle valve opening angle;
sends signal to engine control unit
Installed on throttle body
Transfer pump (4WS) Pumps fuel from the left to the right side Controlled by fuel pump control unit
Transfer pump switch (4WS) Detects fuel level in left section;
sends signal to control unit
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
Water thermo switch (Unleaded fuel) Detects radiator coolant temperature; sends signal to engine control unit ON: above 17°C (63°F)
76G04C-088
4C-50

4C PRC SYSTEM
PRESSURE REGULATOR CONTROL
(PRC)
SYSTEM
Distributor (Ne signal)
I Fuel
(To fuel tank)
76G04C-128
To prevent percolation of the fuel during idle after the engine is restarted, vacuum is cut to the pres-
sure regulator, increasing the fuel pressure.
Specified time: Approx. 120 sec.
Operating condition: Coolant temperature — above 70°C (158°F)
Intake air temperature — above 30°C (86°F)....Unleaded fuel
above 50°C (122°F)....Leaded fuel
4C-68

PRC SYSTEM 4C
COMPONENT DESCRIPTION
Component Function Remark
Engine control unit Detects signals from input sensors and switches; con-trols solenoid valve (Pressure regulator control)
Ignition switch
(ST position)
Sends engine cranking signal to engine control unit
Intake air thermo sensor Detects intake air temperature; sends signal to engine control unit
Ne signal pick-up Detects crank angle at 180° intervals; sends signal to engine control unit Installed in distributor
Pressure regulator Adjusts fuel pressure supplied to injectors
Solenoid valve (Pres-
sure regulator control)
Controls vacuum to pressure regulator Cuts vacuum when hot
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
Idle switch Detects when throttle valve closed; sends signal to engine control unit ON at idle
76G04C-129
TROUBLESHOOTING
Check the condition of the wiring harness and connections before checking the sensors or switches.
Note
Make the system inspection first. If no problem is found, continue with inspection of the
next system of the Troubleshooting Guide. (Refer to pages 4C—10 and 11.)
Possible
\ cause
\ Page
Solenoid valve (Pres-sure regula-tor control)
Water thermo
sensor
Intake air
thermo
sensor
Engine con-trol unit terminal
System inspection Solenoid valve (Pres-sure regula-tor control) 2K
Symplon 4C—70 4C—107 4C-110 4C—98 4C—70
Engine stalls or runs rough after hot starting 2 3 4 5 1
76G04C-130
4C-69

DECELERATION CONTROL SYSTEM 4C
COMPONENT DESCRIPTION
Component Function Remarks
Engine control unit Detects signals from input sensors and switches; cuts fuel injection
Idle switch Detects when throttle valve fully closed; sends signal to engine control unit ON at idle
Ne signal pick-up Detects crank angle at 180° intervals; sends signal to engine control unit Installed in distributor
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
76G04C-135
TROUBLESHOOTING
Check the condition of the wiring harness and connectors before checking the sensor or switches.
Note
Make the system inspection first. If no problem is found, continue with inspection of the
next system of the Troubleshooting Guide. (Refer to page 4C—10 and 11.)
Possible cause Water thermo sensor System inspection
Page 4C—107 4C—74
Checking order 2 1
76G04C-136
4C-73

EGR SYSTEM (UNLEADED FUEL) 4C
EXHAUST GAS RECIRCULATION
(EGR)
SYSTEM (UNLEADED FUEL)
This system introduces exhaust gas into the intake manifold to reduce NOx emissions. It operates de-
pending on the engine load, engine speed (1,500—3,500 rpm), engine coolant temperature (above
70°C, 158°F), and radiator coolant temperature (above 17°C, 63°F).
COMPONENT DESCRIPTION
Component Function Remark
EGR control valve Recirculates portion of exhaust gas
EGR modulator valve Controls vacuum acting on EGR control valve
Engine control unit Detects signals from input sensors and switches; con-trols solenoid valve (EGR)
Ne signal pick-up Detects crank angle at 180° intervals; sends signal to engine control unit
Solenoid valve (EGR) Controls vacuum to EGR control valve
Throttle sensor Detects throttle valve opening angle; sends signal to en-
gine control unit
Installed on throttle body
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
Water thermo switch Detects radiator coolant temperature; sends signal to engine control unit ON: above 17°C (63°F)
76G04C-143
AC—17

4C EEC SYSTEM
EVAPORATIVE EMISSION CONTROL
(EEC)
SYSTEM
Water thermo sensor
76G04C-150
Unleaded fuel:
This system stores fuel vapor generated in the fuel tank in the canister when the engine is not running.
The fuel vapor is stored in the canister until it is drawn into the dynamic chamber and burned when
the engine is started.
Leaded fuel:
Fuel vapor generated in the fuel tank flows out to the atmosphere.
COMPONENT DESCRIPTION
Application
Component Function Remark New
model Prevtoui model
Air flow sensor Detects amount of intake air; sends signal to engine control unit
O X
Charcoal canister Stores fuel tank fumes while engine stopped
o X
Engine control unit Detects signals from input sensors and
switches; controls solenoid valves (Purge
control)
o X
Ne signal pick-up Detect crank angle at 180° intervals; sends signal to engine control unit
Installed in distributor o X
Separator Prevents fuel from flowing into charcoal canister
o o
Solenoid valve
(No.1 purge control)
Controls vacuum to solenoid valve (No.2
purge control) and vacuum switch valve
0 X
Solenoid valve (No.2 Purge control)
Controls vacuum to vacuum switch valve o X
Three-way check valve Controls pressure in fuel tank o X
Two-way check valve Controls pressure in fuel tank X o
Vacuum switch valve Regulates evaporative fumes from canis-ter to intake manifold
o X
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
0 X
76G04C-151
4C-80

4C CONTROL SYSTEM
76G04C-207
76G04C-208
Replacement
1. Disconnect the knock sensor connector.
2. Lift the vehicle and remove the intake manifold
bracket.
3. Remove the knock sensor with the SST.
4. Install the knock sensor in the reverse order of
removal.
INTAKE AIR THERMO SENSOR (DYNAMIC
CHAMBER)
Inspection
1. Disconnect the intake air thermo sensor connector.
2. Connect an ohmmeter to the sensor terminals.
3. Check the resistance of the sensor.
Temperature Resistance (kQ)
20°C (68°F) 29.7—36.3
50°C (122°F) 8.4-10.2
85 °C (185°F) 2.5-3.1
4. Reconnect the sensor connector.
Replacement
1. Disconnect the intake air thermo sensor connector.
2. Remove the sensor.
3. Install the sensor.
Note
When installing the sensor, tighten to the
specified torque.
Specified torque:
6.9—8.8 N-m (0.7—0.9 m-kg, 72 in-lb)
76G04C-209
4C—110

4D
FUEL AND EMISSION
CONTROL SYSTEM
(DIESEL)
OUTLINE 4D— 2
SPECIFICATIONS 4D— 2
TROUBLESHOOTING GUIDE 4D— 3
ON-VEHICLE MAINTENANCE 4D— 4
AIR CLEANER ELEMENT 4D— 4
WATER DRAINING 4D— 4
AIR BLEEDING 4D— 4
INJECTION TIMING 4D— 5
IDLE SPEED 4D— 6
EXHAUST SMOKE 4D— 6
INTAKE AIR SYSTEM 4D— 7
STRUCTURAL VIEW 4D— 7
AIR DUCT AND AIR CLEANER 4D— 8
INTAKE MANIFOLD 4D— 9
SUPERCHARGING SYSTEM (RF-CX) 4D-10
TROUBLESHOOTING GUIDE 4D—10
ON-VEHICLE INSPECTION 4D—11
COMPREX SUPERCHARGER 4D—13
STARTING VALVE 4D—15
INTERCOOLER 4D—16
BOOST AIR TEMPERATURE SENSOR 4D—17
EXHAUST SYSTEM 4D—18
STRUCTURAL VIEW 4D—18
EXHAUST MANIFOLD 4D—19
EXHAUST PIPE AND MAIN SILENCER .... 4D—20
FUEL SYSTEM 4D—21
STRUCTURAL VIEW 4D—21
FUEL FILTER 4D—22
SEDIMENTER (GENERAL) 4D—22
WATER LEVEL SENSOR 4D—23
INJECTION PUMP 4D—24
INJECTION NOZZLE 4D—31
FUEL TANK 4D—34
76G04D-001

4D SUPERCHARGING SYSTEM (RF-CX)
SUPERCHARGING SYSTEM (RF-CX)
TROUBLESHOOTING GUIDE

Engine
hard
starting

Poor

acceleration

Excessive

blue
smoke

Excessive

black
smoke

Excessive

compressed
air
temperature
(Buzzser
sounds)

Excessive

noise
Possible Cause Remedy (reference page)
*
*
Comprex supercharger Rotor stuck Casing damaged Rotor bearing damaged
Replace (4D—14)
* * * Drive system
of
Comprex supercharger Drive belt loose
or
worn Repair
or

replace
(4D-12) * Idler pulley damaged
Repair
or

replace
(4D-12) * Pulley bolt loose
or
worn
Repair
or

replace
(4D-12)
* Wastegate
Valve
not
open Clean
or
repace (4D-12) ik * Valve
not
closed
Clean
or
repace (4D-12)
* * Starting valve
Valve
not
open Repair
or
replace (4D-15)
* * Valve
not
closed
Repair
or
replace (4D-15) * Bypass valve
not
open
Repair
or
replace (4D-15)
* * Bypass valve
not
closed
Repair
or
replace (4D-15)
* Intercooler dirty Clean
or
replace (4D-16)
* * * * Intake
air
system Fresh
air
side clogged (Air cleaner
ele-
ment,
etc.)

Repair
or
replace * Compressed
air
side clogged (Intercool-
er,
etc.)
Repair
or
replace
* Fresh
air
side leaks
Repair
or
replace
* * * Compressed
air
side leaks
Repair
or
replace
* Exhaust system
Exhaust
gas
breaked Repair
* * * * * Exhaust pipe clogged
Repair
* Silencer damaged
(in
fender,
in air
clean-er,
in air
funnel, Comprex insulator) Repair
or
replace
* Bolt
and nut
loosend Repair
76G04D-022
4D—10

4D SUPERCHARGING SYSTEM (RF-CX)
BOOST AIR TEMPERATURE SENSOR
Removal
Remove the boost air temperature sensor from the
compressed air funnel.
76G04D-039
Thermometer
Inspection
1. Place the boost air temperature sensor in oil.
2. Heat the oil and check continuity of the sensor with
an ohmmeter. Replace if necessary.
Continuity : over 150°C (302°F)
No continuity: below 143°C (289°F)
76G04D-040
Installation
Install the boost air temperature sensor in the com-
pressed air funnel.
Tightening torque:
29—39 N m (3.0—4.0 m-kg, 22—29 ft-lb)
76G04D-041
4D—17