The document outlines an engine control system that utilizes a microcomputer to control various engine functions. It describes 11 input signals that provide sensor data like temperature, pressure, speed. It then explains how the microcomputer uses this data to control 4 main systems - multi-port fuel injection, electronic ignition timing, EGR valve, and idle air control - to optimize the engine for different driving conditions. The microcomputer outputs signals to control the injection, ignition, and various valves and actuators.

1. ENGINE CONTROL
SYSTEM OUTLINE
THE ENGINE CONTROL SYSTEM UTILIZES A MICROCOMPUTER AND MAINTAINS OVERALL CONTROL OF THE ENGINE. AN OUTLINE
OF ENGINE CONTROL IS GIVEN HERE.
1. INPUT SIGNALS
(1) ENGINE COOLANT TEMP. SIGNAL SYSTEM
THE ENGINE COOLANT TEMP. SENSOR DETECTS THE ENGINE COOLANT TEMP. AND HAS A BUILT-IN THERMISTOR WITH A
RESISTANCE WHICH VARIES ACCORDING TO THE ENGINE COOLANT TEMP. THUS THE ENGINE COOLANT TEMP. IS INPUT IN
THE FORM OF A CONTROL SIGNAL TO TERMINAL THW OF THE ENGINE CONTROL MODULE.
(2) INTAKE AIR TEMP. SIGNAL SYSTEM
THE INTAKE AIR TEMP. SENSOR DETECTS THE INTAKE AIR TEMP., WHICH IS INPUT AS A CONTROL SIGNAL TO TERMINAL THA
OF THE ENGINE CONTROL MODULE.
(3) OXYGEN SENSOR SIGNAL SYSTEM
THE OXYGEN DENSITY IN THE EXHAUST EMISSIONS IS DETECTED AND INPUT AS A CONTROL SIGNAL TO TERMINALS OX1
AND OX2 OF THE ENGINE CONTROL MODULE.
(4) RPM SIGNAL SYSTEM
CRANKSHAFT POSITION AND ENGINE RPM ARE DETECTED BY THE CRANKSHAFT POSITION SENSOR. CRANKSHAFT POSITION
AND ENGINE RPM ARE INPUT AS A CONTROL SIGNAL TO TERMINAL NE+ OF THE ENGINE CONTROL MODULE.
(5) THROTTLE SIGNAL SYSTEM
THE THROTTLE POSITION SENSOR DETECTS THE THROTTLE VALVE OPENING ANGLE, WHICH IS INPUT AS A CONTROL
SIGNAL TO TERMINAL VTA OF THE ENGINE CONTROL MODULE, OR WHEN THE VALVE IS FULLY CLOSED, TO TERMINAL IDL.
(6) VEHICLE SPEED SIGNAL SYSTEM
THE VEHICLE SPEED SENSOR INSTALLED INSIDE THE COMBINATION METER, DETECTS THE VEHICLE SPEED AND INPUTS A
CONTROL SIGNAL TO TERMINAL SPD OF THE ENGINE CONTROL MODULE.
(7) PARK/NEUTRAL POSITION SW SIGNAL SYSTEM
THE PARK/NEUTRAL POSITION SW DETECTS WHETHER THE SHIFT POSITION IS IN NEUTRAL OR NOT, AND INPUTS A CONTROL
SIGNAL TO TERMINAL NSW OF THE ENGINE CONTROL MODULE.
(8) A/C SIGNAL SYSTEM
THE OPERATING VOLTAGE OF THE A/C MAGNETIC CLUTCH IS DETECTED AND INPUT IN THE FORM OF A CONTROL SIGNAL TO
TERMINAL ACT OF THE ENGINE CONTROL MODULE.
(9) BATTERY SIGNAL SYSTEM
VOLTAGE IS CONSTANTLY APPLIED TO TERMINAL BATT OF THE ENGINE CONTROL MODULE. WHEN THE IGNITION SW IS
TURNED TO ON, VOLTAGE FOR ENGINE CONTROL MODULE OPERATION IS APPLIED VIA THE EFI RELAY TO TERMINAL +B OF
THE ENGINE CONTROL MODULE.
(10) INTAKE AIR VOLUME SIGNAL SYSTEM
INTAKE AIR VOLUME IS DETECTED BY THE MANIFOLD ABSOLUTE PRESSURE SENSOR AND INPUT AS A CONTROL SIGNAL TO
TERMINAL PIM OF THE ENGINE CONTROL MODULE.
(11) STA SIGNAL SYSTEM
TO CONFIRM THAT THE ENGINE IS CRANKING, THE VOLTAGE APPLIED TO THE STARTER MOTOR DURING CRANKING IS
DETECTED AND IT IS INPUT AS A CONTROL SIGNAL TO TERMINAL STA OF THE ENGINE CONTROL MODULE.
60

2. 2. CONTROL SYSTEM
* MFI (MULTIPORT FUEL INJECTION) SYSTEM
THE MFI SYSTEM MONITORS THE ENGINE REVOLUTIONS THROUGH THE SIGNALS EACH SENSOR (INPUT SIGNALS (1) TO (11))
INPUTS TO THE ENGINE CONTROL MODULE. BASED ON THIS DATA AND THE PROGRAM MEMORIZED IN THE ENGINE CONTROL
MODULE, THE MOST APPROPRIATE FUEL INJECTION TIMING IS DECIDED AND CURRENT IS OUTPUT TO TERMINALS #10 AND #20
OF THE ENGINE CONTROL MODULE, CAUSING THE INJECTORS TO OPERATE (TO INJECT FUEL). IT IS THIS SYSTEM WHICH,
THROUGH THE WORK OF THE ENGINE CONTROL MODULE, FINELY CONTROLS FUEL INJECTION IN RESPONSE TO DRIVING
CONDITIONS. DURING ENGINE CRANKING (SIGNAL INPUT TO TERMINAL STA) OR FOR APPROX. 2 SECONDS AFTER NE SIGNAL
INPUT, COMPUTER OPERATION ENERGIZES (POINT CLOSED) THE FUEL PUMP CIRCUIT INSIDE THE CIRCUIT OPENING RELAY,
CAUSING THE FUEL PUMP TO OPERATE.
* EI (ELECTRONIC IGNITION) SYSTEM
THE EI SYSTEM MONITORS THE ENGINE REVOLUTIONS USING THE SIGNALS (INPUT SIGNALS (1, 4, 5, 10, 11)) INPUT TO THE
ENGINE CONTROL MODULE FROM EACH SENSOR. BASED ON THIS DATA AND THE PROGRAM MEMORIZED IN THE ENGINE
CONTROL MODULE, THE MOST APPROPRIATE IGNITION TIMING IS DECIDED AND CURRENT IS OUTPUT TO TERMINALS IGT1 AND
IGT2 OF THE ENGINE CONTROL MODULE. THIS OUTPUT CONTROLS THE IGNITER TO PRODUCE THE MOST APPROPRIATE
IGNITION TIMING FOR THE DRIVING CONDITIONS.
* EGR CUT CONTROL SYSTEM
THE EGR CUT CONTROL SYSTEM CONTROLS THE VSV (EGR) BY EVALUATING THE SIGNALS FROM EACH SENSOR INPUT TO THE
ENGINE CONTROL MODULE (INPUT SIGNALS (1, 4, 5, 10)) AND BY SENDING OUTPUT TO TERMINAL EGR OF THE ENGINE
CONTROL MODULE.
* IDLE AIR CONTROL SYSTEM
THE IDLE AIR CONTROL SYSTEM (ROTARY SOLENOID TYPE) INCREASES THE RPM AND PROVIDES IDLING STABILITY FOR FAST
IDLE-UP WHEN THE ENGINE IS COLD AND WHEN THE IDLE SPEED HAS DROPPED DUE TO ELECTRICAL LOAD, ETC. THE ENGINE
CONTROL MODULE EVALUATES THE SIGNALS FROM EACH SENSOR (INPUT SIGNALS 1, 4 TO 8, 11)), OUTPUTS CURRENT TO
TERMINALS RSC AND RSO AND CONTROLS THE IDLE AIR CONTROL VALVE.
61

3. ENGINE CONTROL
W −R
B−R B−R
I9
7 AM 2 IG 2 6 B −W B−W B−R
I5 I15
B−R
S T2
W−R
B−W
I7
I1 0
IG NITIO N S W
B− R
B− R
B− R
5 1B
8 IG 2 1 5
C 4
W −R
B− R
5A C IR C U IT
IG N O PE N IN G
R E L AY
2 3
G−B
L−W
6 1K
W −R
I4
B−W
B− O
2 2
L−W
L−W
12 IC 1 13 IC1
5 1
7 IE 1
W −R
EFI
B− R
R EL AY
B− W B−W
I18 I18 I18
L−W
3 2
2 2
2 2
B−W
B−W
B−W
B−W
B −R
1 1
FU EL P U M P
2
1 5A 15 A M
1 1 1 1
F25
W −B
B−R
AM2 EFI
IN JE CTO R N O . 1
IN JE CTO R N O . 3
IN JE CTO R N O . 2
IN JE CTO R N O . 4
6
2 2
2 2 2 2
I5
I7
I6
I8
1 E A2 1 2 EA 1 9 IG 2 2 IG 2
B−R
G
G
Y
Y
B
B B C C
F L M AIN J 1 B C
2. 0L J UN C TIO N
C O N N EC TO R
W−B
G− B
B −R
G
Y
B ATTE R Y L −W
G −B
W −B
Y Y
G G
B− R B−R
I19
EB BG
62

4. Y
G
G −B
B−R
B−R
B−R
L− W
W−R
BR BR
EC
I20
BR
FC
G− B B −R
4 A
9 A
+B
#20
Y W−R
25 B
2 A
BA TT
H 6
BR
# 10
G
12 B
H E ATE D O X Y G EN SE N S O R
10
(B AN K 1 S EN S O R 2)
4
2
O 1 BR BR BR
I20
I15
E1
3
+B
IG 1
2
O /D S O LE N O ID
W
1
2
ODT
B−R B R R
11 A
I20
IG 1
EL1
EL1
(A/T) (A/T) (A/T) (A /T) (A /T)
11
H 3
3
1
O X2
W W
B −R
23 B
HE A TED O X YG EN SE N S O R
OX
IG 1
HT
4
(BA N K 1 S EN SO R 1 )
2
1
B− R W− L W −L
6 A
(SH IE L DE D ) (SH IE LD E D)
+B
I20
HT
IG 1
H T1
W −R
W−R
5 A
BR
HT 2
(S H IE L D ED )
4
3
O X1
BR B
10 B
E1
E 2
I19
OX
E NG IN E C O O LA N T
E 6
TE M P. SE N SO R
2
1
B− R
TH W
G −B
3 B
I1
A ,E 7
ID L E AIR C O N TR O L
VA L V E
RSC
2
3
B
B− R L−R
1 B
I9
I19
IN TA KE AIR TE M P .
S E N SO R
RSO
1
2
1
THA
L 14 B L−B
15 B
B−R
V 1
BR
BR
1
VS V (E G R)
EGR
1
2
B− R B−W B− W
15 A
I19
IG 1
E N G IN E CO N TR O L M O D U L E
J2
E2
BR BR
16 B
JU N C TIO N
I18
I19
B−R
C O N NE CTO R
C
C
E01
BR BR
13 B
EC
BR
BR
PIM
1
2
C
P
4 B
E2
PIM
E03
M 1
BR
26 B
K 1 (SH IE LD E D )
VCC
3
K N O C K S E N SO R LG−R LG − R
18 B
VC
I18
KNK
1
B
8 B
P RE S S U RE SE N SO R
M ANIFO L D A BS O L U TE
BR
L −W
B−R
LG−R
63

5. ENGINE CONTROL
FRO M PO W ER SO UR CE SYSTEM (S EE P AG E 5 0)
*1 : BASIC MODEL (M/T)
*2 : EXCEPT *1
T2 BR 2
THR O TTL E
PO SITIO N
SEN SO R 1
10A 7. 5A
E2 G A UG E O BD−
1
FRO M VE HICL E SPE E D SE NS O R
7 1E 2
TO A/C AM PL IFIER
FRO M PA RK/NE UTRA L
VC ID L VTA
FRO M C LU TC H STAR T
R−L
TO PA RK/N EU TR AL
PO SITIO N SW (A/T)
V
4 2 3
TO O /D M A IN SW
[CO M B. M E TER ]
PO SITIO N SW
1 A
SW (M /T)
C 7 A ,C 8 B
M AL FUN CTIO N
L G −R IN DIC ATO R
LA M P
[C O M B. M ETER] 11 IC2
4 B
BR
GR−L
LG −B
(A /T)
(A /T)
R−W
B− W
Y− G
Y− B
B
Y
L
E 6 A ,E 7 B
19 B 17 B 12 A 14 A 11 B 2 B 3 A 13 A 10 A EN G IN E CO NTR O L M O D UL E
ID L VTA A C1 A CT STA NS W O DS W SP D W
G2 N E− N E+ E1 TE1 IG T1 IGT2 IG F S DL
20 B 9 B 21 B 24 B 8 A 6 B 5 B 7 B 16 A
J 1
G
R
J U NCTIO N
BR
G
B
D C O N N EC TOR
J2
(S HIEL DE D )
D JU NC TION
LG − B
L−Y
CO NN ECTO R
LG
W
V
13 IG 1 B B
D
( SH IEL DED )
(SH IEL DED )
W
G
B
B− L
B− L
G
2 1 8 19 6 5 4 2 2 16
CO N N ECTO R 1
CO N N ECTO R 3
C AM S H AFT P O SITIO N
C R AN KS HA FT PO SITIO N
TE1 IG − TA CH IG T1 IG T2 IG F S DL BA T
DA TA L INK
DA TA L INK
I2
IG NITE R
FP +B E1 SG CG
D 1
D 3
SEN S O R
1 2 1 12 3 5 4
S E NS O R
C 1
W −B
B− R
L −W
(* 2)
BR
BR
BR
C 2
R W
A
BR A J1 I15
I19 JUN CTIO N
JU N CTIO N CO N N EC T O R
CO N NE C TO R
(SH IELD ED ) A
A
BR
L− W
A
14 IG 1
J3
W−B
W−B
(* 2 )
(* 1 )
BR
BR
B− R
EC EC IE
64

6. SERVICE HINTS
E6 (A) , E 7 (B) ENGINE CONTROL MODULE
VOLTAGE AT ENGINE CONTROL MODULE WIRING CONNECTORS
BATT -E1 : ALWAYS 9.0-14.0 VOLTS
PIM -E2 : 3.3-3.9 VOLTS (IGNITION SW AT ON POSITION)
VCC -E2 : 4.5-5.5 VOLTS (IGNITION SW AT ON POSITION)
+B -E1 : 9.0-14.0 VOLTS (IGNITION SW AT ON POSITION)
IDL -E2 : 9.0-14.0 VOLTS (IGNITION SW AT ON POSITION AND THROTTLE VALVE FULLY OPEN)
VTA -E2 : 3.2-4.9 VOLTS (IGNITION SW AT ON POSITION AND THROTTLE VALVE FULLY OPEN)
#10, #20-E01, E03 : 9.0-14.0 VOLTS (IGNITION SW AT ON POSITION)
THA -E2 : 0.5-3.4 VOLTS (IGNITION SW ON AND INTAKE AIR TEMP. 20°C, 68°F)
THW -E2 : 0.2-1.0 VOLTS (IGNITION SW ON AND COOLANT TEMP. 80°C, 176°F)
STA -E1 : 6.0-14.0 VOLTS (ENGINE CRANKING)
IGT1, IGT2-E1 : PULSE GENERATION (ENGINE IDLING)
W -E1 : 9.0-14.0 VOLTS (NO TROUBLE AND ENGINE RUNNING)
TE1 -E1 : 9.0-14.0 VOLTS (IGNITION SW ON AND DATA LINK CONNECTOR 1 TE1-E1 NOT CONNECTED)
0 VOLTS (IGNITION SW ON AND DATA LINK CONNECTOR 1 TE1-E1 CONNECTED)
RESISTANCE AT ENGINE CONTROL MODULE WIRING CONNECTORS
(DISCONNECT WIRING CONNECTORS)
IDL -E2 : INFINITY (THROTTLE VALVE OPEN)
0 KΩ (THROTTLE VALVE FULLY CLOSED)
VTA -E2 : 4.0-11.0 KΩ (THROTTLE VALVE OPEN)
0-6.0 KΩ (THROTTLE VALVE FULLY CLOSED)
THA -E1 : 2.0-3.0 KΩ (INTAKE AIR TEMP. 20°C, 68°F)
THW -E1 : 0.2-0.4 KΩ (COOLANT TEMP. 80°C, 176°F)
NE+ -NE- : 0.14-0.18 KΩ
: PARTS LOCATION
CODE SEE PAGE CODE SEE PAGE CODE SEE PAGE
C1 24 F25 28 (4-DOOR), 29 (2-DOOR) I10 27
C2 24 H3 25 J1 27
C4 26 H6 27 J2 27
C7 A 26 I1 25 J3 27
C8 B 26 I2 25 K1 25
D1 24 I5 25 M1 25
D3 26 I6 25 O1 25
E2 24 I7 25 T2 25
E6 A 27 I8 25 V1 25
E7 B 27 I9 25
: RELAY BLOCKS
CODE SEE PAGE RELAY BLOCKS (RELAY BLOCK LOCATION)
2 22 ENGINE ROOM R/B (ENGINE COMPARTMENT LEFT)
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODE SEE PAGE JUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
1B
20 INSTRUMENT PANEL WIRE AND DRIVER SIDE J/B (LEFT KICK PANEL)
1E
1K 20 ENGINE ROOM MAIN WIRE AND DRIVER SIDE J/B (LEFT KICK PANEL)
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODE SEE PAGE JOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
EA1
30 ENGINE WIRE AND ENGINE ROOM MAIN WIRE (INSIDE OF THE ENGINE ROOM R/B)
EA2
EL1 30 ENGINE WIRE AND TRANSMISSION WIRE (NEAR THE PARK/NEUTRAL POSITION SW)
IC1
32 INSTRUMENT PANEL WIRE AND ENGINE ROOM MAIN WIRE (LEFT KICK PANEL)
IC2
IE1 32 INSTRUMENT PANEL WIRE AND FLOOR WIRE (LEFT KICK PANEL)
IG1
34 ENGINE WIRE AND INSTRUMENT PANEL WIRE (NEAR THE BLOWER UNIT)
IG2
65

7. ENGINE CONTROL
: GROUND POINTS
CODE SEE PAGE GROUND POINTS LOCATION
EB 30 FRONT SIDE OF THE LEFT FENDER
EC 30 RIGHT SIDE OF THE SURGE TANK
IE 32 INSTRUMENT PANEL BRACE LH
36 (4-DOOR)
BG LEFT SIDE OF QUARTER PILLAR
38 (2-DOOR)
: SPLICE POINTS
CODE SEE PAGE WIRE HARNESS WITH SPLICE POINTS CODE SEE PAGE WIRE HARNESS WITH SPLICE POINTS
I4 I15 34 INSTRUMENT PANEL WIRE
I5 I18
34 INSTRUMENT PANEL WIRE
I7 I19 34 ENGINE WIRE
I9 I20
66

8. 67