engine ACURA NSX 1991 Service Manual PDF

Inspection
1 . Reliev e fue l pressur e (se e pag e 11-132 )
2 . Remov e th e servic e bol t o n th e fue l filte r whil e
holdin g th e banj o bol t wit h anothe r wrench . Attac h
th e specia l too l (se e pag e 11-38 ).
3 . Star t th e engine . *Measur e th e fue l pressur e wit h
th e engin e idlin g an d th e vacuu m hos e o f th e fue l
pressur e regulato r disconnecte d fro m th e fue l pres -
sur e regulato r an d pinched .
Pressur e shoul d be :
32 4 - 36 3 kP a (3. 3 - 3. 7 kgf/cm
2, 4 7 - 5 3 psi )
4 . Reconnec t vacuu m hos e to th e fue l pressur e regula -
tor.
Pressur e shoul d be :
250 - 30 4 kP a (2.5 5 - 3. 1 kgf/cm2, 3 6 - 4 4 psi )
FUE LPRESSUR EGAUGE07406-004000 1
CLAMP
FUEL PRESSUR EREGULATO R
If th e engin e wil l no t start , tur n th e ignitio n switc h o n
(II ) wai t fo r tw o seconds , tur n i t off , the n bac k o n
agai n an d rea d th e fue l pressure . I
f th e fue l pressur e i s no t a s specified , firs t chec k th e
fue l pum p (se e pag e 11-142 ). I f th e fue l pum p i s OK ,
chec k th e following :
— If th e fue l pressur e is highe r tha n specified , inspec t
for:
• Pinche d o r clogge d fue l retur n hos e o r line .
• Fault y fue l pressur e regulato r (se e pag e 11-137 ).
• Fault y fue l pum p rela y (se e pag e 11-139 ).
— If th e fue l pressur e is lowe r tha n specified , inspec t
for:
• Clogge d fue l filter .
• Fault y fue l pressur e regulato r (se e pag e 11-137 ).
• Leakage in th e fue l line .
• Fault y fue l pum p rela y (se e pag e 11-139 ).
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Fuel Pum p Rela y
Troubleshootin g Flowchar t
Inspection o f fue l pum p relay .
Tur n th e ignitio n switc h t o STAR T
(III) position .
Does th e engin e start ?
Chec k fo r a n ope n in th e circuit :
1 . Sto p th e engine .
2. Tur n th e ignitio n switc h O N (II) .3. Measur e voltag e betwee n
EC M connecto r termina l F 4
an d bod y ground .
I s ther e batter y voltage ?
Proble m verification :
1 . Star t th e engine . Hol d th e
engin e a t 3,00 0 rp m wit h n o
loa d (A/ T in position ,M/T in neutral ) unti l th e radia -
to r fa n come s on , the n le t i t
idl e fo r a t leas t on e minute .
2. Tur n th e ignitio n switc h OFF .3. Disconnec t # 4 hos e fro m th e
instal l pipe , connec t vacuu m
pum p t o th e hose .
4 . Appl y vacuu m 2 7 t o 4 0 kp a
(200 t o 300 mmHg , 8 to 1 2in.Hg) .
5 . Star t th e engine .
6 . Hol d engin e spee d a t 6,50 0
rpm (A/ T in position ,M/T in neutral) .
7 . Measur e voltag e betwee n
EC M connecto r termina l F 4
an d bod y ground .
I s ther e les s tha n 1. 0 V ? Inspec
t th e fue l pum p resisto r
(se e pag e 11-141 ).
ECM CONNECTO R F (26P )
WIR E SID E O F FEMAL E TERMINAL S
(T o pag e 11-140 )
4 HOS E
CONTRO LBOX
VACUU M PUMP /GAUGEA973X-04 1-XXXX X
Substitut e a known-goo d EC M
an d recheck . I f prescribe d volt -
ag e i s no w available , replac e th e
origina l ECM .
Fue l pum p rela y circui t i s OK .
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Fuel Suppl y Syste m
PGM-F I Mai n Rela y
Troubleshootin g
Is ther e continuity ?
Chec k fo r a n ope n o r shor t i n th e
wire :Measur e voltag e betwee n th e
PGM-F I mai n rela y 4 P connecto r
terminal No . 3 an d bod y ground .
Is ther e batter y voltage ?
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 O N (II) .2. Measur e voltag e betwee n th e
PGM-F I mai n rela y 8 P connec -
tor termina l No . 5 an d bod yground .
PGM-FI MAI N RELA Y 8 P CONNECTO R
WIR E SID E O F FEMAL E TERMINAL S
Repai r ope n i n th e wir e betwee n
th e PGM-F I mai n rela y an d G10 1
(locate d a t righ t middl e o fengine) .
PGM-FI MAI N RELA Y 4 P CONNECTO R
Replac e th e ACG(S ) (2 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 Imain rela y an d th e ACG(S )
(2 0 A ) fuse . WIR
E SID E O F FEMAL E TERMINAL S
I s ther e batter y voltage ?
(T o pag e 11-145 ) Replac
e th e No . 2 FUE L
PUMP , SR S 2 (1 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 Imain rela y an d th e No . 2 FUE L
PUMP , SR S 2 (1 5 A ) fuse .
Engin
e wil l no t start .
Inspectio n o f PGM-F I mai n
rela y an d rela y harness .
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 PGM-F I mai n
rela y 4 P connecto r an d 8 P
connector .
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 . 7 an d
body ground .
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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

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

Intake Air Bypass (IAB) Control System

Description

Satisfactory power performance is achieved by closing and opening the intake air bypass (IAB) control valves. High torque

at low engine speed is achieved when the valves are closed, whereas high power at high engine speed is achieved when

the valves are opened.

INTAKE AIR BYPASS (IAB) CONTROL

SOLENOID VALVE ON

ENGINE SPEED IS ABOVE 4,800 rpm

OPEN: HIGH ENGINE SPEED

IAB CONTROL

SOLENOID

VALVE

To No. 5 BACK-UP LIGHTS

ALTERNATOR TURN SIGNALS

(15 A) FUSE

IAB

CONTROL

DIAPHRAGM

IAB

CONTROL

VALVE
CLOSED: LOW ENGINE SPEEDProCarManuals.com

Emission Contro l Syste m
System Descriptio n
The emissio n contro l syste m include s tw o Thre e Wa y
Catalyti c Converter s (TWCs) , Exhaus t Ga s Recirculatio n
(EGR ) system , Positiv e Crankcas e Ventilatio n (PCV ) sys -
te m an d Evaporativ e Emissio n (EVAP ) Contro l system .
Th e emissio n contro l syste m is designe d t o mee t federa l
an d stat e emissio n standards .
Tailpipe Emissio n
Inspectio n
Do no t smok e durin g thi s procedure . Kee p
an y ope n flam e awa y fro m you r wor k area .
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
the radiato r fa n come s on , the n le t i t idle .
2 . Connec t a tachometer .
3 . Chec k an d adjus t th e idl e speed , i f necessar y (se e
pag e 11-128 ).
4 . War m u p an d calibrat e th e C O mete r accordin g t o
th e mete r manufacturer' s instructions .
5 . Chec k idl e C O wit h th e headlights , heate r blower ,
rea r windo w defogger , coolin g fan , an d ai r condi -
tione r off .
NOTE : (Canada ) Pul l th e parkin g brak e leve r up .
Star t th e engine , the n chec k tha t th e headlight s ar e
off.
CO mete r shoul d indicat e 0.1 % maximum .
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Evaporative Emission (EVAP) Controls

Description

The evaporative emission controls are designed to minimize the amount of fuel vapor escaping to the atmosphere. The

system consists of the following components:

A. Evaporative Emission (EVAP) Control Canister

An EVAP control canister is used for the temporary storage of fuel vapor until the fuel vapor can be purged from the

EVAP control canister into the engine and burned.

B. Vapor Purge Control System

EVAP control canister purging is accomplished by drawing fresh air through the EVAP control canister and into a port

on the throttle body. The purging vacuum is controlled by the EVAP purge control diaphragm valve and the EVAP

control solenoid valve.

EVAP PURGE CONTROL SOLENOID VALVE OFF AFTER

STARTING ENGINE

ENGINE COOLANT TEMPERATURE ABOVE 153°F (67°C)

To No. 5 BACK-UP LIGHTS

ALTERNATOR TURN SIGNALS

(15 A) FUSE

FRESH

AIR
EVAP

PURGE CONTROL

DIAPHRAGM VALVE
EVAP PURGE

CONTROL

SOLENOID VALVE
EVAP PURGE

FLOW SWITCH
C. Fuel Tank Vapor Control System

When fuel vapor pressure in the fuel tank is higher than the set value of the EVAP two way valve, the valve opens and

regulates the flow of fuel vapor to the EVAP control canister.

EVAP

TWO WAY

VALVE
FUEL

FILL CAPProCarManuals.com

Mid Plate Guide
Replacement (cont'd)

5. Install the new mid plate guide with the screw
installed.

MII D PLATE GUIDE
SCREW
MI D PLATE

6. Install the washer, spring and guide collar, then
remove the screw.

GUIDE COLLAR

SCREW SPRI
NG

WASHER
MID PLATE GUIDE

Install as shown.

7. Initialize the mid plate guides after installing the
clutch assembly (see page 12-14)

assembly Flywheel, Flywheel Bearing
Inspection
NOTE: If replacement is required, always replace the

pressure plate, mid plate, and flywheel as a set.
1. Inspect the ring gear teeth for wear and damage.
2. Inspect the clutch disc mating surface on the
flywheel for wear, cracks, and burning.

3. Measure the flywheel runout using a dial indicator through at least two full turns. Push against the
flywheel esch time you turn it to take up the
crankshaft thrust washer clearance.

NOTE: The runout can be measured with engine

installed.

Standard (New): 0.05 mm (0.002 in) max.

Service Limit: 0.15 mm (0.006 in)

If the runout exceeds the service limit, replace the
flywheel.

RING

GEAR

FLYWHEEL

4. Turn the inner race of the ball bearing with your
finger. The bearing should turn smoothly and quiet-

ly. Check that the bearing outer race fits tightly in
the flywheel. Replace the bearing if the race does

not turn smoothly, quietly, or fit tightly in the

flywheel.

BALL
BEARING

FLYWHEELProCarManuals.com

Transmission Assembly

Removal

20. Remove the intermediate shaft heat cover and the intermediate shaft mounting bolts.
21. Pry the intermediate shaft out of the differential. Pull and remove it. NOTE:
• Coat all precision finished surfaces with clean engine oil or grease.
• Tie plastic bags over the driveshaft ends.

Corrosion resistant bolt/nut
INTERMEDIATE SHAFT
SUPPORT BASE
INTERMEDIATE SHAFT INTERMEDIATE SHAFT
HEAT COVER
INTERMEDIATE SHAFT
MOUNTING BOLT
22. Remove the parking brake cable holder and the wheel sensor wire clamp.
23. Remove the bolt, and separate the toe control arm from the side beam (see section 18).
24. Remove the damper fork bolt (see section 18).
25. Remove the bolts, and separate the lower control arm from the side beam. 26. Pry the driveshaft out of the differential. Pull and remove it. NOTE:
• Coat all precision finished surfaces with clean engine oil or grease.
• Tie plastic bags over the driveshaft ends.

Corrosion resistant bolt/nut
DAMPER FORK BOLT SELF-LOCKING NUT

Replace.

TOE CONTROL ARM
WHEEL SENSOR WIRE CLAMP PARKING BRAKE
CABLE HOLDER
FLANGE BOLT
LOWER CONTROL ARM SELF-LOCKING NUTReplace. ADJUSTING

BOLT
ADJUSTING

CAM
SELF-LOCKING NUT

Replace.
SET RING

Replace.ProCarManuals.com