1991 ACURA NSX Service Repair Manual

(From pag e 11-144 )
Chec k fo r a n ope n in th e wire :
Measur e voltag e betwee n th e
PGM-F I mai n rela y 4 P connecto r
termina l No . 4 an d bod y ground . PGM-F
I MAI N RELA Y 4 P CONNECTO R
I s ther e batter y voltage ? —
Replac e th e I G COI L (3 0 A )
fus e i n th e engin e compart -
men t fuse/rela y box .
— Repai r ope n o r shor t i n th e
wir e betwee n th e PGM-F I
mai n rela y an d th e I G COI L
(3 0 A ) fuse . WIR
E SID E O F FEMAL E TERMINAL S
Chec k fo r a n ope n o r shor t i n th e
wire :
1 . Tur n th e ignitio n switc h t o th e
STAR T (III ) position .
NOTE:• M/T : Clutc h peda l mus t b e
depressed .
• A/T : Transmissio n in
position .
2 . Measur e th e voltag e betwee n
th e PGM-F I mai n rela y 8 P con -
necto r termina l No . 3 an d
bod y ground . PGM-F
I MAI N RELA Y 8 P CONNECTO R
WIR E SID E O F FEMAL E TERMINAL S
I s ther e batter y voltage ? —
Replac e th e No . 7 STARTE R
SIGNA L (7. 5 A ) fus e i n th e
under-das h fus e box .
— Repai r ope n o r shor t i n th e
wir e betwee n th e PGM-F I
mai n rela y an d th e No . 7
STARTE R SIGNA L (7. 5 A ) fuse .
Chec k fo r a n ope n in th e wire :
1 . Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e EC M connec -
to r A (2 6 P ) fro m th e ECM .
3 . Chec k fo r continuit y betwee n
th e PGM-F I mai n rela y 8 P
connecto r termina l No . 2 an d
EC M connecto r termina l A4 .
WIRE SID E O F FEMAL E TERMINAL S
I s ther e continuity ? Repai
r ope n i n th e wir e betwee n
th e EC M (A4 ) an d th e PGM-F I
mai n relay .
(T o pag e 11-146 )
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Fuel Suppl y Syste m
PGM-F I Mai n Rela y
(From pag e 11-145 )
Chec k fo r a n ope n in th e wire :
1 . Reconnec t th e EC M connecto r
A (26P) .2. Reconnec t th e PGM-F I mai n
rela y 4 P an d 8 P connectors .
3 . Tur n th e ignitio n switc h O N (II) .
4 . Measur e voltag e betwee n
EC M connecto r terminal s
A13, C1, an d A12 .
ECM CONNECTOR S
WIRE SID E O F FEMAL E TERMINAL S
I s ther e batter y voltage ? Repai
r ope n i n th e wir e
betwee n th e EC M (A13 , C D
an d th e PGM-F I mai n relay .
Replac e th e PGM-F I mai n
relay.
Chec k fo r a n ope n in th e ECM :
1 . Tur n th e ignitio n switc h OFF .
2 . Measur e voltag e betwee n
EC M connecto r terminal s A 4
an d A1 2 whe n th e ignitio n
switc h i s firs t turne d o n fo r
tw o seconds .
Is ther e 1. 0 V or less ?
Substitut e a known-goo d EC M
an d recheck . I f prescribe d volt -
ag e is no w available , replac e th e
origina l ECM .
Chec k th e PGM-F I mai n rela y
(se e pag e 11-143 ).
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Fuel Tan k
Replacemen t
Do no t smok e whil e workin g o n fue l system . Kee p ope n flam e awa y fro m you r wor k area .
Mak e sur e lift s ar e place d properl y (se e sectio n 1 ).
1 . Rais e th e car .
2. Remov e th e drai n bolt , an d drai n th e fue l int o a n approve d container .
3 . Remov e th e cente r ro d (se e sectio n 5 ).
4 . Disconnec t th e M/ T shif t cabl e an d M/ T clutc h cabl e o r A/ T shif t cabl e fro m th e transmissio n (se e sectio n 14 ).
5 . Remov e th e bulkhea d panel s (se e se ctio n 20 ) an d acces s panel .
6 . Disconnec t th e C48 6 (6P ) connector .
7 . Disconnec t th e hoses .
CAUTION : Whe n disconnectin g th e hoses , slid e bac k th e clamps , the n twis t hose s a s yo u pull , t o avoi d damagin g
them .
8 . Plac e a jack , o r othe r support , unde r th e tank .
9 . Remov e th e stra p bolt s an d nuts , an d le t th e strap s fal l free .
10 . Remov e th e fue l tank .
NOTE : Th e tan k ma y stic k o n th e undercoa t applie d t o it s mount . T o remove , carefull y pr y i t of f th e mount .
11 . Instal l a ne w washe r o n th e drai n bolt , the n instal l part s i n th e revers e orde r o f removal .
C486 CONNECTO R (6P )
ACCES S
PANE L
TAN K STRAP S FUE
L FILTE R
DRAI N BOL T
49 N- m (5. 0 kgf-m ,36 Ibf-ft )
LOCKNU T
2 1 N- m (2. 1 kgf-m ,
1 5 Ibf-ft )
MOUNTIN G BOL T38 N- m (3. 9 kgf-m , 2 8 Ibf-ft )WASHE
R
Replace .
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Intake Air System

System Description

The system supplies air for all engine needs. It consists of the intake air pipe, Air Cleaner (ACL), intake air duct, throttle

body, and intake manifold. A resonator in the intake air duct provides additional silencing as air is drawn into the system.

IAB CONTROL

SOLENOID VALVE

To No. 5 BACK-UP LIGHTS

ALTERNATOR TURN SIGNALS

(15 A) FUSE

IAB

CONTROL

DIAPHRAGM

IAB

CONTROL

VALVE
THROTTLE

VALVE
INTAKE

AIR DUCT
ACL
RESONATOR
VARIOUS

SENSORS

INTAKE

MANIFOLDProCarManuals.com

Air Cleaner (ACL)

ACL Element Replacement

ACL HOUSING

COVER

ACL ELEMENT

Normal conditions:

Replace air cleaner element every

30,000 miles (48,000 km) or 24

months whichever comes first.

Severe conditions:

Clean air cleaner element every

15,000 miles (24,000 km) or 12

months and replace every 30,000

miles (48,000 km) or 24 months

whichever comes first.

ACL HOUSING

RESONATOR

INTAKE

AIR DUCTProCarManuals.com

Intake Ai r Syste m
Throttl e Cabl e
Inspection/Adjustmen t
1 . Remov e th e accelerato r positio n senso r cover .
2. Chec k tha t th e throttl e cabl e operate s smoothl y wit h
no bindin g o r sticking . Repai r a s necessary .
3 . Chec k cabl e fre e pla y a t th e throttl e linkage . Cabl e
deflectio n shoul d b e 1 0 - 1 2 m m (0.3 9 - 0.4 7 in.) .
ACCELERATO RPOSITIONSENSOR COVE R
DEFLECTIO N10 - 1 2 m m(0.3 9 - 0.47 in. )
LOCKNU T
CABLE
BRACKE T
ADJUSTIN G NU T
4. I f deflectio n i s no t withi n specs , loose n th e locknut ,
tur n th e adjustin g nu t unti l th e deflectio n i s a s spec -
ifie d the n retighte n th e locknut . Installatio
n
1 . Rotat e th e throttl e linkag e counterclockwise , the n
instal l th e throttl e cabl e i n th e throttl e linkag e an d
instal l th e cabl e housin g i n th e cabl e bracket .
THROTTL E LINKAG E
CABLE
BRACKE T
INNERWIRE
LOCKNU TADJUSTIN GNUT
2. Hol d th e cabl e sheath , removin g al l slac k fro m th e
cable .
3. Tur n th e adjustin g nu t unti l i t i s 3 m m (0.1 2 in. )
awa y fro m th e cabl e bracket .
4 . Tighte n th e locknut . Th e cabl e deflectio n shoul d no w
b e 1 0 - 1 2 m m (0.3 9 - 0.4 7 in.) . I f not , se e inspection /
adjustment .
LOCKNUT9.8 N- m(1.0 kgf-m ,
7. 2 Ibf-ft )
ADJUSTIN GNUT
CABL EBRACKE T
3 m m(0.1 2 in. )
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Throttle Bod y
Descriptio n
The throttl e bod y is o f th e single-barre l side-draf t type .
Th e lowe r portio n o f th e throttl e valv e i s heate d b y
engin e coolan t whic h is fe d fro m th e cylinde r head . Th e
idl e adjustin g screw , whic h increases/decrease s bypas s
air , an d th e evaporativ e emissio n (EVAP ) contro l caniste r
por t ar e locate d o n th e to p o f th e throttl e body .
IDLE ADJUSTIN GSCREW
THROTTL E VALV ECONTRO L MOTO R
TPSENSO RTHROTTL EVALVE
Inspectio n
CAUTION : D o no t adjus t th e throttl e sto p screw . I t i s
prese t a t th e factory .
1. Star t th e engine . Hol d th e engin e a t 3,00 0 rp m wit h
no loa d (A/ T in position , M/ T in neutral ) unti l
th e radiato r fa n come s on , the n le t i t idle .
2. Disconnec t th e vacuu m hos e (t o th e EVA P contro l
canister ) fro m th e to p o f th e throttl e body ; connec t
a vacuu m gaug e to th e throttl e body .
VACUU M PUMP/GAUG EA973X-04 1-XXXX X
3. Allo w th e engin e t o idl e an d chec k tha t th e gaug e
indicate s n o vacuum .
• I f ther e i s vacuum , chec k th e throttl e cabl e (se e
page 11-150 ).
4 . Chec k tha t vacuu m is indicate d o n th e gaug e whe n
th e throttl e is opene d slightl y fro m idle .
• I f th e gaug e indicate s n o vacuum , chec k th e
throttl e bod y port . I f th e throttl e bod y por t i s
clogged , clea n it wit h carbureto r cleaner .
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Intake Air System

Throttle Body

Disassembly

THROTTLE BODY

IDLE ADJUSTING

SCREW

O-RING

Replace.

THROTTLE VALVE

CONTROL MOTOR

INTAKE AIR DUCT
TP SENSOR

22 N-m

(2.2 kgf-m,

16 Ibf-ft)ProCarManuals.com