1987 MAZDA 626 Workshop Manual

4C INTAKE AIR SYSTEM
REMOVAL
Caution
Before removing the following parts, release the fuel pressure from fuel system to reduce
the possibility of injury or fire. (Refer to page 4C—52.)
Remove in the sequence shown in the figure, referring to the removal note.
1. Air cleaner
2. Air flow sensor
3. Air hoses
4. Connectors (Idle switch,
ISC, Throttle sensor)
5. Water hoses
6. Vacuum hoses
7. Accelerator cable
8. Throttle body
9. Gasket
10. PCV hose
4C-32
11. Vacuum pipe assembly
(Unleaded fuel)
12. Dynamic chamber brackets
13. Connectors (Knock sensor,
Intake air thermo sensor)
14. Dynamic chamber
15. One-way check valve
16. Gasket
17. Wiring harness
(for injectors)
18. Fuel hoses
76G04C-053
19. Delivery pipe assembly
mounting bolt.
20. Heat insulator
21. Injectors
22. Delivery pipe assembly
23. EGR pipe
24. Intake manifold bracket
25. Solenoid valve
26. Intake manifold
27. Gasket
28. Air duct
29. Resonance chamber

INTAKE AIR SYSTEM 4C
76G04C-054
76G04C-055
76G04C-056
Removal Note
Water hose
Before disconnecting the water hose, drain two liters
of engine coolant.
Delivery pipe assembly.
1. Separate the fuel return pipe from the delivery pipe
assembly.
2. Remove the delivery pipe assembly and the fuel
return pipe.
PARTS INSPECTION
Air Cleaner Element
1. Check the condition of the air cleaner element.
2. Blow out the dust with compressed air, if
necessary.
Caution
a) The air cleaner must be replaced at the in-
tervals outlined in the maintenance
schedule.
b) Never drive the vehicle without the air
cleaner element, otherwise, damage to the
air flow sensor (hot wire) will occur.
c) Never use an oil permeated air cleaner ele-
ment, otherwise, contamination of the hot
wire will occur.
4C—33

4C INTAKE AIR SYSTEM
Air Cleaner Case
1. Check that the steel plate mounted on the upper
case is grounded.
2. Replace, if necessary.
76G04C-058
Accelerator Cable
1. Inspect the deflection of the cable. If it is not with-
in 1—3 mm (0.04—0.12 in.), adjust by turning
nuts A.
2. Depress the accelerator pedal to the floor and con-
firm that the throttle valve is fully opened. Adjust
by turning bolt B if necessary.
76G04C-059
Throttle Body
Note
The No. 2 throttle valve is preset at the facto-
ry to begin opening after the No. 1 throttle
valve has opened approx. 25 degrees.
1. Check that the No. 1 and No. 2 throttle valves move
smoothly when the throttle lever is moved from fully
closed to fully open.
2. Replace, if necessary.
76G04C-060
Caution
Do not remove the thin sealing coating from
the throttle valve or bore.
69G04C-050
4C-34

INTAKE AIR SYSTEM 4C
69G04A-062
69G04A-064
Shutter valve
69G04C-051
Dynamic Chamber
1. Visually check the dynamic chamber for damage.
2. Replace, if necessary.
Intake Manifold
1. Visually check the intake manifold for damage.
2. Replace, if necessary.
Shutter Valves
1. Visually check the shutter valves for damage.
2. Check that the shutter valves close and open fully.
3. Adjust or replace them if necessary.
Resonance Chamber
1. Visually check the resonance chamber for
damage.
2. Replace if necessary.
69G04C-054
4C—35

4C INTAKE AIR SYSTEM

(4)
Outer washer
©Spacer
ru , ©iNut and spring (2) Throttle lever Washer
69G04C-130
Inner washer
69G04C-131
Outer washer
Spacer
REPLACEMENT
Throttle Lever
Removal
Caution
When loosening the throttle lever nut, hold the
throttle valves fully open to prevent damag-
ing the idle switch.
Remove the throttle lever in the sequence shown in
the figure.
Installation
1. Check that the inner washer is in the proper posi-
tion as shown in the figure.
2. Assemble the spacer and outer washer and install
them onto the throttle shaft.
3. Install the throttle lever onto the throttle shaft.
Caution
When tightening the throttle lever nut, hold
the throttle valves fully closed to prevent
bending the stopper lever.
4. Tighten the throttle lever nut.
Tightening torque:
16—23 N m (1.6—2.3 m-kg, 12—17 ft-lb)
5. Check that the inner and outer washer and spacer
are assembled correctly as shown.
6. Check that No.1 and No.2 throttle valves move
smoothly and that No.2 throttle valve is closed com-
pletely when the No.1 throttle valve is closed.
7. Check the operation of the idle switch.
(Refer to page 4C—106.)
76G04C-061
4C—36

INTAKE AIR SYSTEM 4C
INSTALLATION
Install in the reverse order of removal, referring to the installation note.
Torque Specification
19—26 N-m (1.9—2.6 m-kg, 14—19 ft-lb)
8—11 N-m (0.8—1.1 m-kg, j 69—95 in-lb)
8—11 N-m (0.8—1.1 m-kg, 69—95 ft-lb)
19—26 N-m .9—2.6 m-kg, 14—19 ft-lb)
8—11 N-m (0.8—1.1 m-kg, 69—95 in-lb)
37—52 N-m (3.8—5.3 m-kg, ' 27—38 ft-lb)
4.2—6.2 N-m (43—63 cm-kg, 37—55 in-lb)
19—26 N-n (1.9-2.6 m-kg, 14—19 ft-lb)
B6U04A-D55
4C—37

4C INTAKE AIR SYSTEM
Installation Note
Water hose spring clamps
Face the clamp end as shown in the figure.
Gasket
Use new gaskets at the intake manifold, dynamic
chamber, and throttle body.
86U04A-056
• . v 1
Engine 1 Ml' ' •-
hanger ^ •
• i::£?^Solenoid valve bracket
Air cleaner. r^I. ^jUvW;
Th V
Ground harnesses
Make sure that the ground harnesses are tightened
securely at the following positions.
(1) Air cleaner upper case
(2) Solenoid valve braket
(3) Engine hanger
76G04C-062
Solenoid valve connectors
Connect the solenoid valve connectors at the posi-
tions shown in the figure.
76G04C-063
Inspection after installation
1. After completing installation, fill up the engine with
the specified engine coolant.
2. Warm up the engine and run it at idle.
3. Check for any vacuum, coolant, or fuel leaks.
76G04C-064
4C-38

VIC SYSTEM 4C
VARIABLE INERTIA CONTROL
(VIC)
SYSTEM
The VIC system supplements the intake air's inertial effect to create a torque band that runs from low
rpm through the high rpm range.
The system consists of the intake manifold, shutter valves, dynamic chambers, actuator, one-way check
valve, three-way solenoid valve, and engine control unit.
Shutter valve
Shutter valve
76G04C-065
Intake Inertia Effect
The air within the dynamic chamber and intake manifold begins to flow during the first half of the air
intake process. This air flow pushes air into the cylinder by its own inertial force during the second
half of the air intake process. This improves the charging of the cylinder.
To most effectively put this inertia charging to use, the length of the manifold leading to the dynamic
chamber needs to be changed in response to the engine rpm.
Length of intake manifold Intake inertia effect
Long Effective at low and middle speed
Short Effective at high speed
The VIC system controls the length of the intake manifold travel by switching the shutter valve either
open or closed at the specified engined rpm.
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4C—39