1997 ACURA NSX Service Repair Manual

PGM-FI Syste m
System Descriptio n
INPUTSENGIN E CONTRO L MODUL E (ECM )OUTPUT S
Front Primar y H02 S
Rea r Primar y HO2 S
Fron t Secondar y HO2 S
Rea r Secondar y H02 S
MA P Senso r
CKP/CY P Senso rECT Senso rTP Senso rAP Senso rIAT Senso rVSSFron t K SRea r K SEG R Valv e Lif t Senso rA/TFI Signal sTCS Signal s
Spar k Plu g Voltag e
Detectio n Modul e Signa l
Starte r Signa l
Brak e Switc h Signa l
AL T F R Signa l
Ai r Conditionin g Signa l
A/ T Gea r Positio n Switc h Signa l
Neutra l Switc h Signa l (M/T )
Clutc h Switc h Signa l (M/T )
VTE C Pressur e Switc h
Batter y Voltag e (IGN . 1 )
Fue l Tan k Pressur e Senso r
Cruis e Contro l Mai n Switc h Signa l
Se t Switc h Signa l
Resum e Switc h Signa l Fue
l Injector s
PGM-F I M.ai n Rela y (Fue l Pump )
Malfunctio n Indicato r Lam p
Throttl e Valv e Contro l Moto r
A/ C Compresso r Clutc h Rela y
ICMEVA P Purg e Contro l Solenoi d Valv e
EVA P Bypas s Solenoi d Valv e
EVA P Contro l Caniste r
Ven t Shu t Valv e
Fue l Pum p Rela y
EG R Contro l Solenoi d Valv e
IA B Contro l Solenoi d Valv e
VTE C Solenoi d Valve s
Fron t Primar y H02 S Heate r
Rea r Primar y H02 S Heate r
Fron t Secondar y H02 S Heate r
Rea r Secondar y H02 S Heate r
Cruis e Contro l Indicato r Ligh t
Revers e Lockou t Rela y
DLC
PGM-F I Syste m
Th e PGM-F I syste m o n thi s mode l i s a sequentia l multipor t fue l injectio n system .
Fue l Injecto r Timin g an d Duratio n
Th e EC M contain s memorie s fo r th e basi c discharg e duration s a t variou s engin e speed s an d manifol d pressures . Th e
basi c discharg e duration , afte r bein g rea d ou t fro m th e memory , i s furthe r modifie d b y signal s sen t fro m variou s sensor s
t o obtai n th e fina l discharg e duration .
Throttl e Valv e Contro l
Th e EC M control s th e throttl e valv e contro l moto r base d o n accelerato r peda l position , TC S contro l uni t signals , an d vari -
ou s othe r signals . Th e EC M als o control s th e idl e contro l function , cruis e contro l function , an d othe r function s wit h th e
throttl e valv e control .
Ignitio n Timin g Contro l
Th e EC M contain s memorie s fo r basi c ignitio n timin g a t variou s engin e speed s an d manifol d pressures . Ignitio n timin g
i s als o adjuste d fo r engin e coolan t temperature .
A knoc k contro l syste m is als o used . Whe n detonatio n i s detecte d b y th e knoc k senso r (KS) , th e ignitio n timin g i s
retarded .
Other Contro l Function s
1 . Startin g Contro l
Whe n th e engin e is started , th e EC M provide s a ric h mixtur e b y increasin g fue l injecto r duration .
2 . Fue l Pum p Contro l
Whe n th e ignitio n switc h i s initiall y turne d o n (II) , th e EC M supplie s groun d t o th e PGM-F I mai n rela y tha t supplie s
curren t t o th e fue l pum p fo r tw o second s t o pressuriz e th e fue l system .
Whe n th e engin e is running , th e EC M supplie s groun d to th e PGM-F I mai n rela y tha t supplie s curren t t o th e fue l pump .
Whe n th e engin e i s no t runnin g an d th e ignitio n i s on , th e EC M cut s groun d t o th e PGM-F I mai n rela y whic h cut s
curren t t o th e fue l pump .
Excellen t engin e performanc e is achieve d throug h th e us e o f VTE C (Variabl e Valv e Timin g an d Valv e Lif t Electroni c
Contro l System) , intak e ai r bypas s contro l an d discharg e volum e contro l o f th e fue l pump .
(cont'd )
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PGM-FI System

System Description (cont'd)

3. Fuel Cut-off Control

During deceleration with the throttle valve closed, current to the fuel injectors is cut off to improve fuel economy at

speeds over 1,500 rpm.

Fuel cut-off action also takes place when engine speed exceeds 8,300 rpm, regardless of the position of the throttle

valve, to protect the engine from over-revving.

4. A/C Compressor Clutch Relay

When the ECM receives a demand for cooling from the air conditioning system, it delays the compressor from being

energized, and enriches the mixture to assure smooth translation to the A/C mode.

5. Evaporative Emission (EVAP) Purge Control Solenoid Valve

When the engine coolant temperature is below 153°F (67°C), the ECM controls the EVAP purge control solenoid valve

which cuts vacuum to the EVAP purge control canister diaphragm.

6. Intake Air Bypass (IAB) Control Solenoid Valve

When the engine speed is below 4,800 rpm, the IAB control solenoid valve is activated by a signal from the ECM. Intake

air then flows through the smaller chamber, and high torque is delivered. To increase air flow at engine speeds higher

than 4,800 rpm, the solenoid valve is deactivated by the ECM, and the intake air flows through the larger chamber.

7. Exhaust Gas Recirculation (EGR) Control Solenoid Valve

When the EGR is required for control of oxides of nitrogen (NOx) emissions, the ECM supplies ground to the EGR

control solenoid valve which supplies regulated vacuum to the EGR valve.

ECM Fail-safe/Back-up Functions

1. Fail-Safe Function

When an abnormality occurs in a signal from a sensor, the ECM ignores that signal and assumes a pre-programmed

valve for that sensor that allows the engine to continue to run.

2. Back-up Function

When an abnormality occurs in the ECM itself, the fuel injectors are controlled by a back-up circuit independent of the

system in order to permit minimal driving.

3. Self-diagnosis Function [Malfunction Indicator Lamp (MIL)]

When an abnormality occurs in a signal from a sensor, the ECM lights the MIL and stores the diagnostic trouble code

in erasable memory. When the ignition is initially turned on, the ECM supplies ground for the MIL for two seconds to

check the MIL bulb condition.

4. Two Trip Detection Method

To prevent false indications, the Two Trip Detection Method is used for the H02S, fuel metering-related, idle control

system, ECT sensor, EGR system self-diagnostic functions and EVAP control system. When an abnormality occurs,

the ECM stores it in its memory. When the same abnormality recurs after the ignition switch is turned OFF and ON (II)

again, the ECM informs the driver by lighting the MIL.

However, to ease troubleshooting, this function is cancelled when you short the service check connector. The MIL will

then blink immediately when an abnormality occurs.

5. Two (or three) Driving Cycle Detection Method

A "Driving Cycle" consists of starting the engine, beginning closed loop operation, and stopping the engine. If misfir-

ing that increases emissions or EVAP control system malfunction is detected during two consecutive driving cycles,

or TWC deterioration is detected during three consecutive driving cycles, the ECM turns the MIL on.

However,
to
ease
troubleshooting,
this
function
is
cancelled when
you
short
the
service check connector.
The MIL
will

then blink immediately when an abnormality occurs.ProCarManuals.com

Engine Contro l Modul e (ECM )
NOTE: I f thi s sympto m is intermittent , chec k fo r a loos e No . 5 BACK-U P LIGHTS , ALTERNATOR ,
TUR N SIGNAL S (1 5 A ) fus e in th e under-das h fuse/rela y box , a poo r connectio n a t EC M termina l
A7 , o r a n intermitten t ope n in th e BL U wir e betwee n th e EC M (A7 ) an d th e gaug e assembly .
I s th e lo w oi l pressur e ligh t on ?
Tr y t o star t th e engine .
Doe s th e engin e start ?
Chec k fo r a n ope n in th e wir e o r
bulb :
1. Tur n th e ignitio n switc h OFF .2. Connec t th e EC M connecto r
termina l A 7 t o bod y groun d
with a jumpe r wire .3. Tur n th e ignitio n switc h O N (II) .
Is th e MI L on ?
Substitut e a known-goo d ECM ,
an d rechec k (se e pag e 11-3 9 fo r
immobilize r information) . I f symp -
tom/indicatio n goe s away , replac e
the origina l ECM .
— Repai r shor t i n the wir e
betwee n No . 5 BACK-U P
LIGHTS , ALTERNATOR , TUR N
SIGNAL S (1 5 A ) fus e an d
gaug e assembly .
— Replac e No . 5 BACK-U P
LIGHTS , ALTERNATOR , TUR N
SIGNALS (15 A) fuse.
Chec k fo r a n ope n in th e wire s
(PG lines) :1. Tur n th e ignitio n switc h O N (II) .
2 . Measur e voltag e betwee n
bod y groun d an d EC M con -
necto r terminal s A1 2 an d A2 5
individually .
I s ther e les s tha n 1. 0 V ?
Substitut e a known-goo d EC M
an d rechec k (se e pag e 11-3 9 fo r
immobilize r information) . I f symp -
tom/indicatio n goe s away , replac e
th e origina l ECM . Repai
r ope n i n th e wire(s )
betwee n EC M an d G10 1 (locate d
a t intak e manifold ) tha t ha d
mor e tha n 1.0V .
— Repai r ope n i n th e wire s
betwee n EC M (A7 ) an d gaug e
assembly .— Replac e th e MI L bulb .
(cont'd )
Turn th e ignitio n switc h O N (II) .
The Malfunctio n Indicato r Lam p
(MIL ) neve r come s o n (eve n fo r
tw o seconds ) afte r ignitio n i s
turne d O N (II) .
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PGM-FI Syste m
Engine Contro l Modul e (ECM ) (cont'd )
The Malfunctio n Indicato r Lam p
(MIL ) stay s o n o r come s o n afte r
tw o seconds .
Chec k th e Diagnosti c Troubl e
Code (DTC) :1. Connec t a sca n too l o r Hond a
PG M Tester .
2. Tur n th e ignitio n switc h O N (II) .3. Rea d th e DT C wit h th e sca n
too l o r Hond a PG M Tester .
NOTE:• Whe n ther e is n o Diagnosti c Troubl e Cod e (DTC ) stored , th e MI L wil l sta y o n if th e SC S servic e
connecto r i s connecte d an d th e ignitio n switc h i s on .
• I f thi s sympto m is intermittent , chec k for :
— A loos e ACG(S ) (2 0 A ) fus e in th e engin e compartmen t fuse/rela y bo x
— A loos e No . 2 FUE L PUM P SRS 2 (1 5 A ) fus e in th e under-das h fus e bo x
— A n intermitten t shor t i n th e wire betwee n th e EC M (C5 ) an d th e servic e chec k connecto r
— A n intermitten t ope n i n th e wire s betwee n th e EC M (A26 , B14 ) an d th e servic e chec k con -
necto r
— A n intermitten t shor t i n th e wire betwee n th e EC M (A7 ) an d th e gaug e assembl y
— A n intermitten t shor t i n th e wir e betwee n th e EC M (F1 ) an d th e MA P sensor , accelerato r posi -
tion senso r— A n intermitten t shor t i n th e wir e betwee n th e EC M (D10 ) an d th e T P sensor , EG R valv e lif tsenso r— A n intermitten t shor t i n th e wire betwee n th e EC M (F14 ) an d accelerato r positio n senso r
• Se e th e OB D II sca n too l o r Hond a PG M Teste r user' s manual s fo r specifi c operatin g instruc -
tions.
Are an y DTC(s ) indicated ? G
o t o troubleshootin g proce -
dures , (se e pag e 11-38 )
Chec k th e DT C b y MI L indication :
1. Tur n th e ignitio n switc h OFF .2. Connec t th e SC S servic e con -
necto r t o th e servic e chec k
connector .
3. Tur n th e ignitio n switc h O N (II) .
Doe s th e MI L indicat e an y DTC ? —
Repai r ope n o r shor t i n wir e
betwee n the ECM (D4 ) an d
Dat a Lin k Connector .
— G o t o troubleshootin g proce -
dures , (se e pag e 11-38 )
Try t o star t th e engine .
Does th e engin e start ?
Chec k fo r a shor t i n th e wir e
(SC S line) :
1 . Sto p th e engin e an d tur n th e
ignitio n switc h O N (II) .2. Measur e voltag e betwee n th e
EC M connecto r termina l C 5
an d bod y ground . (T
o pag e 11-63 )
I s ther e approx . 5 V ?
(T o pag e 11-63 ) Repai
r shor t t o bod y groun d i n
th e wir e betwee n EC M (C5 ) an d
servic e chec k connector .
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(From pag e 11-62 )
Chec k fo r a shor t i n th e wir e (MI L
line) :
1. Tur n th e ignitio n switc h OFF .2. Disconnec t th e EC M connec -
to r A (26P) .
3. Tur n th e ignitio n switc h O N (II) .
Is th e MI L ON ?Repai r shor t t o bod y groun d i n
th e wir e betwee n th e EC M (A7 )
and MIL .
Substitut e a known-goo d EC M
an d rechec k (se e pag e 11-3 9 fo r
immobilize r information) . I f symp -
tom/indicatio n goe s away , replac e
the origina l ECM .
(From pag e 11-62 )
Inspec t ACG(S ) (2 0 A ) fus e i n th e
engin e compartmen t fuse/rela ybox.
Is th e fus e OK ? Repai
r shor t i n th e wir e
betwee n ACG(S ) (2 0 A ) fus e
an d PGM-F I mai n relay .
Replac e ACG(S ) (2 0 A ) fuse .
Inspec t I G COI L (3 0 A ) fus e i n th e
engin e compartmen t fuse/rela ybox.
Is th e fus e OK ? Repai
r shor t i n th e wir e
betwee n I G COI L (3 0 A ) fus e
an d PGM-F I mai n relay .
Replac e IG COI L (3 0 A ) fuse .
Chec k fo r a shor t i n a sensor :
1. Tur n th e ignitio n switc h O N (II) .2. Disconnec t th e 3 P connecto r
o f eac h senso r on e a t time :
• MA P senso r
• T P senso r
• EG R valv e lif t senso r• Fue l tan k pressur e senso r
Doe s th e MI L remai n ON ? Replac
e th e senso r tha t cause d
the ligh t t o g o out .
(To pag e 11-64 )(cont'd )
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PGM-FI Syste m
Engine Contro l Modul e (ECM ) (cont'd )
(From pag e 11-63 )
Chec k fo r a shor t i n th e A P sen -
sor:1. Tur n th e ignitio n switc h OFF .2. Connec t th e SC S servic e con -nector .3. Disconnec t th e A P senso r 3 P
connector .
4. Tur n th e ignitio n switc h O N (II) .
Is DT C P124 6 and/o r P124 7
indicated ?
Chec k fo r a shor t i n th e wire s
(VC C lines) :
1. Tur n th e ignitio n switc h OFF .2. Disconnec t th e EC M connec -tor D (22P ) an d F (26P) .3. Chec k fo r continuit y betwee nbody groun d an d EC M con -necto r terminal s D10 , F 1 an dF14 individually .
Is ther e continuity ?
I s ther e batter y voltage ?
Chec k fo r a n ope n i n th e wire s
(L G lines) :
1 . Reconnec t al l senso r connec -
tors .
2 . Reconnec t th e EC M connecto r
D (22P ) F (26P) .3. Tur n th e ignitio n switc h O N (II) .4. Measur e voltag e betwee n
bod y groun d an d EC M connec -
tor terminal s A2 6 an d B 9 indi -vidually .
Is ther e les s tha n 1.0V ?
Substitut e a known-goo d EC Mand rechec k (se e pag e 11-3 9 fo r
immobilize r information) . I f symp -
tom/indicatio n goe s away , replac e
th e origina l ECM . Replac
e th e A P sensor .
Repai r shor t t o bod y groun d
in th e wir e betwee n EC M(D10 ) an d throttl e angl e sen -
so r an d EG R valv e lif t sensor .
Repai r shor t t o bod y groun d in
th e wir e betwee n EC M (F1 )and MA P senso r Accelerato r
Positio n senso r o r fue l tan k
pressur e sensor .
Repai r shor t t o bod y groun d in
th e wir e betwee n EC M (F14 )and Accelerato r Positio n sen -sor.
Repai r ope n i n th e wire(s )
betwee n EC M (A13 , C D an d
PGM-F I mai n relay .
Chec k fo r poo r connection s
o r loos e wire s a t th e PGM-F I
mai n relay .
Repai r ope n i n th e wire(s )
between EC M (A26 , B9 ) an dG10 1 tha t ha d mor e tha n 1. 0 V .
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Drive B y Wir e Syste m
System Descriptio n
The Driv e B y Wir e Syste m is a n electroni c throttl e contro l system .
Thi s syste m consist s of the throttl e valv e contro l moto r an d Throttl e Positio n (TP ) senso r assemble d i n Throttl e Bod y (TB) ,
th e accelerato r positio n sensor , an d th e Engin e Contro l Modul e (ECM) .
Driv e B y Wir e Syste m Functions :
Idl e Contro l Functio n
Whe n th e engin e i s idling , th e EC M control s th e throttl e valv e contro l moto r t o maintai n th e prope r idl e spee d accordin g
t o engin e loads .
Acceleratio n Contro l Functio n
Whe n th e accelerato r peda l i s depressed , th e EC M open s th e throttl e valv e dependin g o n th e accelerato r positio n senso r
signals .
(cont'd)
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Drive By Wire System

System Description (cont'd)

Cruise Control Function

The ECM controls the throttle valve control motor to maintain the set speed when the cruise control system is operating.

The throttle valve control motor takes the place of the cruise control actuator.

Traction Control System (TCS) Function

If wheel spin occurs during acceleration or cornering, the TCS control unit requests the ECM to reduce the engine power

by retarding the ignition timing and closing the throttle valve. If the wheels lock during deceleration, the TCS control unit

signals the ECM to open the throttle valve.

Engine Protection Function

When the engine speed exceeds 8,000 rpm (M/T) or 7,500 rpm (A/T), the ECM controls the throttle valve, regardless of the

accelerator position, to protect the engine from over-revving.

Fail-safe Function

On this system, the ECM monitors the position of the accelerator pedal with a dual circuit type accelerator position sensor,

and monitors the operation of the throttle valve control motor with a Throttle Position (TP) sensor.

When an abnormality occurs in the system, the ECM restricts the operation of the throttle valve control motor to allow the

engine to continue to run.ProCarManuals.com