Page 283 of 1164

OUTLINE
Component Function Remark
Engine control unit (ECU) Controls operation of the following:
(Cont’d)
1. A/C (Cut-off) 1. A/C relay
2. Fail-safe function 2. Self-Diagnosis Checker and MIL
3. Fuel injection system 3. Injector
4. idle speed control 4. Idle speed control (ISC) valve
5. Ignition timing control system 5. Igniter
6. Monitor function 6. Monitor lamp (Self-Diagnosis Checker)
7. Pressure regulator control system 7. Solenoid valve
(Pressure regulator control) (BP)
8. Purge control system 8. Purge control solenoid valve
9. VICS 9. Solenoid valve (WCS) (DOHC) Fuel filter
Filters particles from fuel Fuel pump
Provides fuel to injectors l Operates while engine running l Installed in fuel tank Igniter
Receives spark signal from ECU and gener-
ates high voltage in ignition coil Ignition switch
Engine cranking signal sent to ECU (START position)
Inhibitor switch (ATX)
Detects in-gear condition; sends signal to Switch ON in N or P range
ECU Injector
Intake air thermosensor
Idle speed control (ISC)
valve
Main relay
(FUEL INJ relay)
MIL (Malfunction
indicator lamp)
Neutral switch (MTX)
Oxygen sensor
PCV valve
P/S pressure switch
Pressure regulator
Resonance chamber
Resonance duct
Separator
Stoplight switch
Solenoid valve
(Purge control)
Shutter valve actuator
(DOHC)
Throttle body
Throttle sensor
Injects fuel into intake port l Controlled by signals from ECU
l High-ohmic injector
Detects intake air temperature; sends signal Installed on dynamic chamber
to ECU
Controls bypass air amount Controlled by duty signal from ECU
Supplies electric current to injectors, ECU,
etc.
Lamp flashes to indicate malfunction code
number of input and output devices
Detects in-gear condition; sends signal to
ECU
Detects oxygen concentration; sends signal
to ECU
Controls blowby gas introduced into engine
Detects P/S operation; sends signal to ECU
Adjusts fuel pressure supplied to injectors
Reduces intake air noise
Reduces intake air noise
Prevents fuel from flowing into charcoal
canister
Detects braking operation (deceleration),
sends signal to ECU
Controls evaporative fumes from canister to
intake manifold
Closes/opens shutter valve to improve
torque characteristics
Controls intake air quantity
l Detects throttle valve fully closed/fully
opened condition (MTX) TEN terminal grounded
Switch ON in neutral
Zirconia ceramic and platinum coating
P/S: ON when steering wheel turned right or
left
Controlled by duty signal from ECU
For Variable inertia charging system (VICS*)
Integrated throttle sensor, dashpot, and ISC
valve
l Detects throttle valve opening angle
(A-W
l Sends signals to ECU
F-l 7
Page 284 of 1164
F OUTLINE
I Component
I Function
I Remark
I
Three-way
solenoid
valve vIcs*
Pressure
regulator
control
Controls vacuum to shutter valve actuator
Controls vacuum to pressure regulator Cuts vacuum when engine speed above
5.000 ram
Cuts vacuum just after starting when engine
hot starting Vacuum chamber
(DOHC)
Water thermosensor
Stores vacuum for use during wide open For WCS*
throttle
Detects coolant temperature; sends signal to
ECU
l WCS: Variable Inertia Charging System 23UOFX-013
F-l 8
Page 286 of 1164

F TROUBLESHOOTING GUIDE
TROUBLESHOOTING GUIDE
ENGINE CONTROL OPERATION CHART
Note
Input Device and Engine Conditions
l The data in this chart is for reference only.
INPUT DEVICES APPROX,- SENSORS
MATE TIME G& THROTTLE SENSOR
(BASED ON TRIBUTOR
WATER INTAKE
10-16°C, (G. OXYGEN AIRFLOW AIR
VT
POW
.50-6OOF
SIGNAL)” ;;;;;f- SENSOR METER
AMBIENT) (Ne-SIGNAL) THERMO- TERMINAL TERMINAL yE\MINAL
CONDITIONS SENSOR (ATX)
WX)
A
c
CRANKING
-COLD ENGINE Signal has Signal has Signal has Signal has Slgnal has Slgnal has
l COLD AIR zero no affect no effect no effect no effect no effect
no effect
. COLD COOLANT on ECU on ECU on ECU on ECU on ECU
on ECU
Cool to A A
COLD START
warm: Low volume Closed Closed
Closed
-FAST IDLE
One
Medium airflow: throttle: throttle:
l COLD AIR
minute
voltage High volt-
Low volt- Low volt- throttle.
Low volt-
* COLD COOLANT
(3.5” and :zo:o, ,,Pbove 1’,“,“$; a(ogi-O,8”) ;149&“) we W)
dropping) to high
(68OF)]:
COLD DRIVEAWAY voltage A
Above
-PART THROTTLE Two (O-0.9”) 2.3”
l COLD AIR minutes
l COLD COOLANT
v v ,,
Warm: Medi- Sensor Moderate II
WARM DRIVEAWAY
volume air-
-PART THROTTLE Three N&IGNAL um voitage hot:
flow: Low
l WARM AIR minutes Sends all Vvwrox switching l WARM COOLANT cylinders 0.7V and
from high to medium
Part Part
TDC signal dropping) voltage voltage
throttle: throttle.
)
A (0.9V) (1 .o-3.5”)
to ECU
.“~ Medium Medium
HOT CRUISE
s voltage voltage
Open
l WARM AIR G-
SIGNAL”’ to low (0.8-3.0”) (4.5-5.5”) throttle:
l WARM COOLANT High
Sends No. voltage
1 cylinder (0.1”) voltage
1 (battery
TDC (com-
1 I voltage)
HOT ACCELERATION pression)
-60% THROTTLE signal to
Moderate
ECU
to strong
High Cool lo warm
voltage ;$,“,” Of j-20-4OT
f t
HOT ACCELERATION
More’ than Hot: Low (0.9”) Low (-4-‘04”F)l: W,ds open
voltage 1.5-4.3v
throttle: Wide open
-WIDE OPEN
four voltage
High volt- throttle
THROTTLE (0.5-1.5V)
minutes (Below High
0.5”) age (Above
voltage (OV)
t 1 3.OV)
I,
A 1. /I
DECELERATION
-CLOSED THROTTLE
HOT CURB IDLE
-EXTENDED
HOT ENGINE
SHUTDOWN Low
voltage
(0”) Low Closed Closed
Closed
volume throttle: throttle.
throttle.
of airflow:
~~~~!$$ (Above Low Low
Low
voltage voltage
voltage
to low 3.OV) (0.2-0.N) (4.5-5 5V) (OV)
voltage
(0.75%
t t 1 0.25”)
r v 1 I I
Sensor
hot: Low
OFF OFF voltage
-
(0.1”) until OFF OFF OFF OFF
OFF
sensw
COOIS
._-
Page 288 of 1164
F TROUBLESHOOTING GUIDE
Output Devices and Engine Conditions
Note
. The data in this chart is for reference only.
INJECTOR
CONDITIONS
CRANKING
-COLD ENGINE
l COLD AIR l COLD COOLANT
COLD START
-FAST IDLE
l COLD AIR l COLD COOLANT
COLD DRIVEAWAY
-PART THROTTLE
l COLD AIR l COLD COOLANT
WARM DRIVEAWAY
-PART THROTTLE
. WARM AIR
l WARM COOLANT
HOT CRUISE
l WARM AIR l WARM COOLANT Zero
One
mrnute
Two
minutes
Three
minutes
I AIR
INJECTION “AL”E
INJECTION TlMlNG
A
All A
cylinders
each
ignition
pulse
1
Rich Open:
coolant
tem-
perature:
Below
40%
(104OF)
,
I/
Rich and
2-group” 1’
lean l-group” /I
,
i
HOT ACCELERATION
-60% THROTTLE
-lOT ACCELERATION
-WIDE OPEN
THROTTLE
Closed ISC
VALVE
1, THREE-WAY
SOLENOID SOLENOID
VALVE VALVE
(PURGE
(PRESSURE
CONTROL) REGULATOR
CONTROL)‘3
c
OFF
(Purge
cut)
Large
1
, AK
RELAY
amount or
bypass air
OFF
(Vacuum
to
pressure
regulator)
After start-
rng: ON dur-
ing hot start
only (Vacu-
um cut)
OFF
l 2 SOHC, *’ BP
F-22
Page 289 of 1164
TROUBLESHOOTING GUIDE F
THREE-
WAY
SOLE-
NOID
VALVE
(WCS)”
ON
(Vacuum
to shutter
valve
actuator)
A
Engine
speed
below
5,000
rpm:
3FF
(Vacuum
wt)
I
3N
:Vacuum
:o shutter
Jalve
actuator)
OFF
23UOFX-01
F-23
Page 292 of 1164

F TROUBLESHOOTING GUIDE
Troubleshooting chart
6 I
CRANKS NORMALLY BUT HARD TO START - WHEN ENGINE COLD
*Engine cranks at normal speed but requires excessive crankmg time before starting
IESCRIP-
l Batterv in normal condition
llON l Restans OK after warmup l Engine runs normally at idle [If Idle condrtron is not OK, refer to “Rough idle” (Nos. S-12)]
TROUBLESHOOTING HINTS]
B Air/Fuel mrxture too rrch @Air/Fuel mixture too lean
l Arrflow meter stickrng l Fuel iniectron control malfunction
l Aw cleaner element clogged
*Idle weed control malfunction (Correction for coolant temperature)
0 Poor atomizatron
- ~~ ~~ *Low RVP (summer) fuel is used rn cold weather >
f INSPECTION T Check If “00” is displayed on Self-Diagnosis
Checker wth Ignition switch ON -
Yes
No CT page F-73
SYSTEM SELECT: 1
“SELECT SW: A
Check if ECU terminal voltages are OK
(Especially 1C. 2D. and 2Q)
cc page F-144
Check If engine starts easily when throttle valve -
Yes
-
NO
-
Yes ACTION
Go to next step
Malfunctlon Code No. dlsplayed
Check for cause (Refer to specified
check sequence)
“58” flashes CT- page F-79
Check ECU terminal 1F voltage
Speciflcetlon: Battery voltage CT page F-144
(Ignition ewltch ON)
+ If OK, replace ECU CT page F-143
e If. not OK, check wrring between
ECU and Self-Diagnoos Checker
Go to next step
Check for cause CI page F-145
(-!hnrlr ,‘ ICP ..-I..- .^ nv
c+ page F-103
13UOFX-009
DESCRIPTION:
Further describes the symptom. Confirm that the chart addresses the actual symptom before beginning
troubleshooting.
TROUBLESHOOTING HINTS:
This describes the possible point of malfunction.
STEP:
This shows the order of troubleshooting. Proceed with troubleshooting as indicated.
INSPECTION:
This describes an inspection to quickly determine the malfunction of parts. If a detailed procedure is necessary
to perform the INSPECTION, refer to the page shown by the “~7” mark.
ACTION:
This recommends the appropriate action to take as a result (Yes/No) of the INSPECTION. How to perform
the action is described on the reference page shown by the “~7” mark.
OWOFX-016
F-26
Page 293 of 1164

TROUBLESHOOTING GUIDE
DIAGNOSTIC INDEX
No. TROUBLESHOOTING ITEM DESCRIPTION
1 Will not crank or cranks slowly Refer to Engine Electrical System PAGE
G- 4
Engine cranks at normal speed but shows no sign of 1 F-30
Engine cranks at normal speed but shows only par-
I
tial combustion and will not continue to run
Engine starts normally when cold, but will not start af-
After warm-up
5 Cranks normally but
Always
hard to start Engine cranks at normal speed but requires exces-
sive cranking time before starting F-36
F-38
I----
F-40 Same condition as No.5 when engine cold
Restarts normally after warm-up
Same cond;ion as No.5 after running and hot
soaked
Starts normally when cold
8
H
Rough idle
9 (Low idle speed)/
Engine stalls at idle Enaine stalls or vibrates excessivelv at idle
Engine stalls or vibrates excessively at idle during
warm-up 1 F-42
F-44
Engine runs normally at idle during warm-up but
vibrates excessively or stalls after warm-up
Engine stalls or vibrates excessively at idle when
A/C, P/S, or E/L ON F-46
F-46
starting (acceleration from idle)
l---- Engine stalls or vibrates excessively only just after
Idle speed excessive after warm-up 1 F-50 F-49 12 Rough idle/Engine stalls just after starting
13 High idle speed after warm-up
1 14 1 Idle moves up and down/Idle hunting Engine speeds up and down periodically at idle
1 F-52
I l5 I Engine stalls on deceleration
Engine unexpectedly stops running while decelerat-
ing or after deceleration F-54
Engine intermittently stops running
Flat spot occurs just after accelerator depressed or
mild jerkrng occurs during acceleration
Unexpected change in engine speed which is usually
repetitive F-56
F-57
F-59 16 Engine stalls suddenly (Intermittent)
17 Hesitates/Stumbles on acceleration
1 18 1 Surges while cruising
19
I I
Lack of power Performance poor under load when throttle valve F-61
wide open
Maximum speed reduced
Performance poor-while accelerating
-I- F-65 20 Poor acceleration
21 Runs rough on deceleration/Backfire Engine runs rough while decelerating and abnormal
combustion occurs in exhaust system F-69
Abnormal combustion accompanied by audible
“pinging” noise
Gasoline odor in cabin 22 Knocking
23 Fuel odor
24 Exhaust sulfur smell
26 High oil consumption Exhaust gas smells abnormal
Oil consumption excessive
Fuel economy unsatisfactory 1 26 1 Poor fuel economy 1 F-75
Self-Diagnosis Checker does not indicate malfunction
23UOFX~O’
F-27
Page 294 of 1164
F TROUBLESHOOTING GUIDE
Description of Drivability
STUMBLE : Mild jerking during acceleration.
HESITATION: Flat spot occurring just after the accelerator pedal is depressed.
SURGE : Continuous soft jerking during cruise.
ENGINE SPEED
1
I No.18 SURGE
F-28