1992 MAZDA PROTEGE ECU

iTEP INSPECTION ACTION
5 Connect System Selector to diagnosis connector Yes
and set Test Switch to “SELF TEST” and check Check if ignition timing advances when
for correct ignition timing at idle after warm-up accelerating w page F-79
* If advances, go to next step
r3 If not advance, check ECU terminal Ignition timing (BTDC)
voltages l BP DOHC : go--ll” w page F-150 l BP SOHC : 4O-6O
. B6 : 6O-6O
No
Adjust w page F-79
6
Check if ECU terminal voltages are OK
Yes Go to next step w page F-150
No
Check for cause ~7 page F-151
7
Check for correct intake manifold vacuum at idle
Yes Go to next step Intake manifold vacuum:
More than 450 mmHg (17.7 inHg) No
Check for air leakage of intake air sys-
tem components
8 Check for correct fuel line pressure at idle
Yes Check if fuel line pressure decreases w page F-129
when accelerating quickly Fuel line pressure:
265-314 kPa (2.7-3.2 kg/cm’, 39-46 psi)
(Vacuum hose to pressure regulator dls-
connected)
d If decreases, check fuel pump
maximum pressure (3‘ page F-126
If OK, check fuel line and filter for
clogging
* If not decrease, go to next step
No Low pressure
Check for fuel line pressure while pinch-
ing fuel return hose
c3 If fuel line pressure quickly in-
creases, check pressure regulator w page F-129
+ If fuel line pressure gradually in-
creases, check for clogging be-
tween fuel pump and pressure
regulator
If not clogged, check fuel pump
maximum pressure w page F-126
High pressure
Check if fuel line is clogged
* If OK, replace pressure regulator w page F-130
c3 If not OK, replace
F-66

F TROUBLESHOOTING GUIDE
iTEF
___
13
14
-
15
__
16 INSPECTION
Change fuel and check if acceleration improves
Check if A/C cut-off control system is OK
Check if variable inertia charging system (WCS)
is OK (BPD)
w page F-l 18
Try known good ECU and check if condition
improves
w page F-149 ACTION
Yes Change fuel to another brand
No Go to next step
Yes SOHC
Go to Step 16
DOHC
Go to next step
No Repair or replace
Yes Go to next step
I
No 1 Repair or replace /
F-68

TROUBLESHOOTING GUIDE F
21 RUNS ROUGH ON DECELERATION/BACKFIRE
IESCRIP.
*Engine runs rough while decelerating and abnormal combustion occurs in exhaust system
MON l Transaxle in normal condition TROUBLESHOOTING HINTS]
1) Arr/Fuel mixture too rich
l Arr cleaner element clogged
l Fuel injection control malfunctron
(Fuel cut control)
l Injector fuel leakage
*Throttle sensor (IDL terminal) malfunction
l Dashpot malfunctron
er with ignition switch ON
Check ECU terminal 1F voltage w page F-150
Specification: Battery voltage
(Ignition switch ON)
+ If OK, replace ECU w page F-149 6 If not OK, check wiring between
ECU and Self-Diagnosis Checker
----~
Check for cause (Refer to specified
check sequence) w page F-106
SELECT SW: A Vacuum: More than 450 mmHg (17.7 inHg)
tern components
4 Check if air cleaner element is clean Yes
Go to next step w page F-79
No
Replace air cleaner element
5 Check if ECU terminal voltages are OK
Yes Go to next step
MTX...Especially lN, 2A, 2U and 2V
ATX... Especially lT, 3A, 3U and 3V CT page F-150
No Check for cause c=i‘ page F-151
F-69

F TROUBLESHOOTING GUIDE
r TEP INSPECTION
ACTION
6 Check if fuel cut operation is OK
Yes Go to next step
CT page F-143
No Try known good ECU and check if con-
dition improves
w page F-149
7 Check if airflow meter is OK
Yes Go to next step
w page F-166
I. Check if measuring plate moves smoothly
II. Check resistance No Repair or replace
8 Check if throttle sensor IDL terminal is OK
Yes Go to next step
w page F-169
No Adjust CT page F-169
9 Check if dashpot is correctly adjusted
Yes Check if throttle valve is contaminated
w page F-142
+ If contaminated, clean throttle body
Dashpot set speed: * If not contaminated, replace throttle
E”P . . . . . . . ..*.*....................
Approx. 3,000 rpm body
SOHC . . . . . . . . . . . . . . . . . . . . . .
Approx. 2,700 rpm
BP DOHC . . . . . . . . . . . . . . . . . . . . . . Approx. 3,600 rpm
No Adjust w page F-142
IO Check injector for fuel leakage
Yes Replace
w page F-132
No Go to next step
11 Try known good ECU and check if condition
improves
w page F-149
23UOFX-037
F-70

22 KNOCKING
DESCRIP- *Abnormal combustion accompanied by audible “pinging” noise
I-ION
[TROUBLESHOOTING HINTS]
3 Incorrect ignition timing (Too advanced)
@ Air/Fuel mixture too lean
3 Carbon deposits in cylinder
*Fuel injection amount not correct
3 Overheating
l Fuel line pressure decreases while accelerating
TEP INSPECTION
ACTION
1 Connect System Selector to diagnosis connector
Yes Go to next step
and set Test Switch to “SELF TEST” and check
for correct ignition timing at idle after warm-up
CT page F-79
Ignition timing (BTDC)
l BP DOHC : go-1 1 o l BP SOHC : 4”-6O
’ B6 No
Adjust a page F-79
2 Check if “00” is displayed on Self-Diagnosis
Yes Go to next step
Checker with ignition switch ON
W page F-62
No
Service Code No. displayed
Check for cause (Refer to specified
check sequence) w page F-63
“88” flashes
Check ECU terminal 1F voltage CT page F-150
Specification: Battery voltage
(Ignition switch ON)
c3 If OK, replace ECU w page F-149
W: SELF TEST c3 If not OK, check wiring between
ECU and Self-Diagnosis Checker
3 Check for correct intake manifold vacuum at idle
Yes Go to next step
VaCUUm: More than 450 mmHg (17.7 inHg) No
Check for air leakage of intake air sys-
tem components
4
Check for correct engine compression
Yes Go to next step
w page Bl-10
B2-10
Engine compression (Minimum):
l BP DOHC
883 kPa (9.0 kg/cm’, 128 psi)-300 rpm
l BP SOHC
834 kPa (8.5 kg/cm*, 121 psi)300 rpm
l B6
932 kPa (9.5 kg/cm’, 135 psi)300 rpm No High compression
Check engine condition CI page 81-10
62-l 0 l Carbon deposits
F-71

F TROUBLESHOOTING GUIDE
STEP INSPECTION ACTION
5 Check for correct fuel line pressure at idle Yes Check if fuel line pressure decreases
w page F-129 when accelerating quickly
Fuel line pressure: + If it decreases, check for clogging
265-314 kPa (2.7-3.2 kg/cm’, 36-46 psi) between fuel pump and pressure
(Vacuum hose to pressure regulator dis- regulator
connected) * If not decrease, go to next step
INSTALL CLAMPS No Low pressure
Check fuel line pressure while pinching
fuel return hose
c3 If fuel line pressure quickly in-
creases, check pressure regulator w page F-129
c3 If fuel line pressure gradually in-
creases, check for clogging be-
tween fuel pump and pressure
regulator
If not clogged, check fuel pump
maximum pressure w page F-126
6 Check if cooling system is OK Yes Go to next step
w page E-13
No Repair or replace
l Thermostat w page E-9
l Electric cooling fan w page E-16 l Radiator w page E-6
7 Try known good ECU and check if condition Yes Replace ECU CT page F-149
improves
CT= page F-149 No
Change fuel to another brand or use
higher octane fuel
23lJOFX.0: .-._ ,
F-72

TROUBLESHOOTING GUIDE F
23 FUEL ODOR
DESCRIP-
*Gasoline odor in cabin
TION [TROUBLESHOOTING HINTS]
@ Poor connection or damaged at fuel system or evaporative emission control system
@ Charcoal canister overflow due to evaporative emission control System malfUnCtiOn
Check for cause (Refer to specified Specification: Battery voltage
(Ignltlon switch ON)
c3 If OK, replace ECU r;+ page F-149 c3 If not OK, check wiring between
ECU and Self-Diagnosis Checker
control) with engine running and throttle valve
opened (Neutral switch connector disconnected)
eck if vacuum is felt
s
23UOFX-029
F-73

TROUBLESHOOTING GUIDE F
26 POOR FUEL ECONOMY
DESCRIP-
l Fuel economy unsatisfactory TION
[TROUBLESHOOTING HINTS]
While fuel consumption is drastically increased by city driving, short-run operation, stop and go driving, extended winter
warm-up periods, etc., as opposed to “trip” mileage, an attempt should be made to determine these factors when con-
fronted with “poor mileage” conditions. However, since the operator is not always at fault, the following is offered.
@II Operator depressing accelerator more than usual due to
@ Air/Fuel mixture too rich
low engine power
l Poor ignition *High fuel line pressure
@ Alcohol blended fuel used
*Low intake air amount
l Electronic spark advance control system malfunction @ High vehicle load l Low tire pressure
*Clutch slipping/ATX slipping l Incorrect tire size l Exhaust component restricted l Brake dragging ;TEP
INSPECTION ACTION
1
Check factors other than engine Yes
Go to next step
l Low tire pressure = Section Q 9 Unrecommended tire srze v Section Q l Clutch slipping w Section H l Brake dragging No
0 Section P Repair
l Exhaust component restricted cz= page F-136
2
Check if air hoses are connected correctly - Yes
Go to next step CI page F-109
No
Repair 3
Check if “00” IS displayed on Self-Diagnosis
Yes
Checker with ignition switch ON Go to next step W page F-82 No
SYSTEM SELECT: 1 Service Code No. displayed Check for cause (Refer to specified
check sequence) w page F-63
“88” flashes
Check ECU terminal 1F voltage w page F-150
Specification: Battery voltage
(Ignition switch ON)
* If OK, replace ECU CT= page F-149 e If not OK, check wiring between
ECU and Self-Diagnosis Checker 4
Check for correct intake manifold vacuum at idle
Yes Go to next step Vacuum: More than 450 mmHg (17.7 inHg) No
Check for air leakage at intake air sys-
tem components 5
Check if air cleaner element is clean Yes
Go to next step CT= page F-79
No
Replace air cleaner element
F-75