1987 MAZDA 626 check engine

EGR SYSTEM 4A
TROUBLESHOOTING
Note
Make the system inspection first. If no problem is found, continue with the next inspec-
tion of the Troubleshooting Guide. (Refer to pages 4A—22.)
Possible cause System inspection EGR control valve Water thermo valve
Page 4A—65 4A—65 4A—66
Checking order 1 2 3
76G04A-123
76G04A-124
76G04A-125
System Inspection
1. Start the engine.
2. Accelerate the engine while it is still cold and check
that the diaphragm of the EGR control valve does
not move.
3. Warm up the engine to normal operating temper-
ature and run it at idle.
Warning
Be careful when checking the EGR control
valve, the surrounding area is very hot.
4. Accelerate the engine and check that the di-
aphragm of the EGR control valve moves.
EGR Control Valve (ATX)
(No. 1)
1. Manually actuate the valves by pushing on the di-
aphragm with finger.
2. Check that the spring resistance is present and the
diaphragm moves freely with no sticking or
binding.
3. Warm up the engine and run it at idle.
4. Connect a vacuum pump to the valve and apply
vacuum.
5. Check that the engine runs roughly or stalls at more
than the specified vacuum.
Specification:
70—90 mmHg (2.8—3.5 inHg)
6. If not correct, replace the EGR control valve.
76G04A-126
4A—65

4A EGR SYSTEM
76G04A-127
76G04A-128
ji C
Blow here *** I
>3 l^v?
> O-—-/ 1)
Ml
r-
(No. 2)
1. Check the EGR control valve manually (same as
No. 1 valve).
2. Warm up the engine and run it at idle.
3. Connect a vacuum pump to the valve and apply
vacuum.
4. Check that the engine runs roughly or stalls at more
than the specified vacuum.
Specification:
70—90 mmHg (2.8—3.5 inHg)
5. If not correct, replace the EGR control valve.
EGR Control Valve (MTX)
1. Check the EGR control valve manually (same as
above).
2. Warm up the engine and run it at idle.
3. Connect a vacuum pump to the valve and apply
vacuum.
4. Check that the engine runs roughly or stalls at more
than the specified vacuum.
Specification:
70—90 mmHg (2.8—3.5 inHg)
5. If not correct, replace the EGR control valve.
Water Thermo Valve
1. Remove the water thermo valve from the bottom
of the inlet manifold.
2. Place the water thermo valve in a container with
water and a thermometer.
3. Gradually heat the water to 50°C (122°F).
76G04A-129
From carburetor
(A)—E
(a)-
To No.1 EGR
control valve and
vacuum switch
Wax
I— (B)
(b)
To No.2 EGR
control valve
76G04A-130
4. Blow air through the water thermo valve from (A),
and check that air comes out from (a).
5. Blow air through the water thermo valve from (B)
and check that air comes out from (b).
6. Replace if necessary.
4A—66

PCV SYSTEM 4A
POSITIVE CRANKCASE VENTILATION
(PCV)
SYSTEM
Air cleaner pcv valve
76G04A-131
This system reburns the blow-by gases and operates while the engine is running to reduce emissions.
PCV VALVE
Inspection
1. Warm up the engine to the normal operating tem-
perature and run it at idle.
2. Disconnect the PCV valve and the ventilation hose
from the cylinder head cover.
3. Block the PCV valve and check that the engine
speed drops.
4. Replace the PCV valve if necessary.
76G04A-132
4A—67

IDLE-UP CONTROL SYSTEM 4 A
FE (Middle East) and F6 (General)
Possible cause
jrvo

diaphragm

3
jrvo

diaphragm

n c o> (0
E 3 3 O
® >
a >
•o o c e
£ O **
S M O
£ O
'i (0 (0
O <
o a
o E W 0)
lm Q.
c a k 4) -
9-5
"S "5 (O > CO < a. DC H Js * OC M
Page 4A—72 4A—74 4A—74 Section 15 4A—75 Section 16
Checking order 1 2 3 4 5 6 7 8
76G04A-136
FE 8Valve—Unleaded Fuel
Posible cause

Engine

control

unit

terminal

Servo

diaphragm

Vacuum

signal

Solenoid

valve £ O **
S CO O
£ U
S <0 U) Relay
(for
A/C) ** n ** w o E «
Refrigerant
pressure

switch
H D I Servo

diaphragm

Vacuum

signal

Solenoid

valve
< a. Relay
(for
A/C)
H Refrigerant
pressure

switch

Page 4A—91 4A—72 4A—74 4A—74 Section 15 4A—75 Section 16
Checking order 9 1 2 3 4 5 6 7 8
76G04A-137
4A—71

4A IDLE-UP CONTROL SYSTEM
Servo Diaphragm
Dual servo diaphragm type
1. Warm up the engine and run it at idle.
2. Connect a tachometer to the engine.
3. Disconnect the vacuum hose from the servo di-
aphragm port A.
4. Apply intake manifold vacuum directly to the di-
aphragm.
Caution
All accessories must be OFF.
76G04A-138
5. Check that the engine speed is within the specifi-
cation.
Engine speed: 1,200—1,400 rpm
6. If not within specification, turn the adjust screw to
adjust.
7. Reconnect the vacuum hoses.
76G04A-139
8. Disconnect the solenoid valve vacuum hose from
the servo diaphragm port B.
9. Apply intake manifold vacuum directly to the di-
aphragm.
10. Check that the engine speed is within specification.
Engine speed: 800—1,000 rpm (MTX)
1,050—1,250 rpm (ATX)
(in N range)
76G04A-140
Adjust screw
11. If not within specification, turn the adjust screw to
adjust.
12. Reconnect the vacuum hoses.
76G04A-141
4A—72

IDLE-UP CONTROL SYSTEM 4A
Single servo diaphragm type
1. Warm up the engine and run it at idle.
2. Connect a tachometer to the engine.
3. Disconnect the vacuum hose from the servo di-
aphragm.
4. Check that the engine speed is within specification.
Engine speed:
P/S operated 800—1,000 rpm (MTX) P/S operated 1,050—1,250 rpm (ATX) (in N range)
A/C operated 1,200—1,400 rpm
76G04A-142
6. If not within specification, turn the adjust screw to
adjust.
76G04A-143
4A-73

4A IDLE-UP CONTROL SYSTEM
76G04A-144
76G04A-145
76G04A-146
Vacuum Signal [Equipped with A/C, only FE and
F8 (Except Middle East and General)]
1. Start the engine and run it at idle.
2. Disconnect the vacuum hose from the servo di-
aphragm.
3. Place a finger over the hose.
4. Increase the engine speed, and check for vacuum.
Engine model Engine speed Vacuum
pj| (Except Middle) Below 2,300 rpm Yes pj| (Except Middle) Above 2,300 rpm No
FE (Unleaded fuel) Below 1,500 rpm Yes FE (Unleaded fuel) Above 1,500 rpm No
F6 (Singapore) Below 2,100 rpm Yes F6 (Singapore) Above 2,100 rpm No
General and Middle East
1. Start the engine and run it at idle.
2. Disconnect the vacuum hose from the servo di-
aphragm.
3. Place a finger over the hose.
4. Operate the A/C or P/S.
5. Check that vacuum is felt.
P/S Switch
1. Start the engine and run it at idle.
2. Disconnect the power steering switch connector.
3. Connect an ohmmeter to the power steering
switch.
4. Turn the steering wheel all the way to either the
right or left, and check for continuity.
P/S Continuity
Operated Yes
Not operated No
5. Replace if necessary.
Solenoid Valve (A/C)
1. Disconnect vacuum hose A from the servo di-
aphragm.
2. Disconnect vacuum hose B from the solenoid
valve.
3. Disconnect the solenoid valve connector.
4. Blow air through the valve from hose A and check
that it comes out of port C.
76G04A-147
4A-74

IDLE-UP CONTROL SYSTEM 4A
Troubleshooting
Note
Make the system inspection first. If no problem is found, continue with the next inspec-
tion of the Troubleshooting. (Refer to page 4A—70.)
\\ Possible cause
\ Page
£ O
S in c o
£ O **
in
0) ** (0 o
o **
s <0
o ** c o o •o d>
£ O **
S (0 o E a>
X 1-<,
£ O
S w £ O
a> > a >
u o c 0) o
c 3
O ** C o
c o s o a> a (0 c
c a E o o
® TJ w <0 4> DC
0) a » c cs IL
a> (0
o
£ C
i « a <
a. 3 a>

Engine

i
terminal
E a>
s. CO
Symptom
Section
15 Section 15 4A—95 4A—93 Section
15 4A—77 4A—86— 4A—91 4A—77
Checking order 3 4 5 6 7 8 2 9 1
76G04A-152
'Engine control unit terminal Check the following terminal voltages
Transmission Terminal
MTX A, C, D, H, Q, R
ATX I, 2B, 2C, 2D, 2E, 2H, 2M
System Inspection
1. Warm up the engine and run it at idle.
2. Connect a jumper wire to the carburetor connec-
tor terminal wire (YW) and ground.
3. Connect a tachometer to the engine.
4. Turn all accessories off.
5. Verify that the engine speed is within specification.
Engine speed: 900—950 rpm (MTX)
Engine speed: 1,000—1,050 rpm
(ATX; in N range)
6. Disconnect the tachometer.
76G04A-153
Idle-up Solenoid Valve
1. Turn all accessories OFF and turn the ignition
switch ON.
2. Disconnect the idle-up solenoid valve connector.
3. Ground the carburetor connector terminal wire
(YW) using with a jumper wire.
4. Check the rod is drawn into the valve.
5. Replace if necessary.
U
76G04A-154
4A-77