light ACURA NSX 1991 Service Repair Manual

Warning/Caution Labe l Location s
SRS CAUTIO N LABELS : Refe r t o pag e 1- 6
FROZE NBATTER Y CAUTIO N
AI R CONDITIONIN G
R-134 a CAUTIO N
(U.S.A. only )
ENGIN E COOLAN TCAUTION • PRECAUTIO N
ABS CAUTIO N
ABS an d BRAK EFLUID CAUTIO N
RETRACTABL EHEADLIGHT CAUTIO N
EMISSION CONTRO L
INFORMATIO N an d
VACUU M HOS E
ROUTIN G DIAGRA M
BATTERYCAUTION
RADIATO R BLEE DPLUG CAUTIO N
EXPANSIO NTANK CA PCAUTIO N
SPAR K PLU G
CAUTIO N
TIRE INFORMATIO N
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Valve Clearance
Adjustment (cont'd)
3. Manually inspect the rocket arms for independentoperation (see page 6-7, 8 ('94-'96), 6-36, 37 ('91-'93).
4. Adjust valves on No.1 cylinder.
• Adjusting screws are on primary and secondary
rocker arms,

Intake: 0.15-0.19 mm (0.006-0.007 in)

Exhaust: 0.17-0.21 mm (0.007-0.008 in)

5. Loosen the locknut, and turn the adjustment screw
until the feeler gauge slides back and forth with a

slight amount of drag.

INTAKE:
TAPPET ADJUSTER

07MAA–PR70110
FEELER

GAUGE

TAPPET LOCKNUT

WRENCH

07MAA–PR70120

EXHAUST: NOTE: Use a mirror to check if the special tool is

positioned on the locknut correctly.

FEELER

GAUGE
6. Tighten the locknut and check the clearance again.
Repeat adjustment if necessary.

INTAKE:
FEELER

GAUGE
LOCKNUT

7 x

0.75
mm

20 N·m
(2.0
kg-m.
14 Ib-ft)

EXHAUST:
FEELER

GAUGE
LOCKNUT

7
x

0.75
mm

20 N·m
(2.0
kg-m,

14 Ib-ft)ProCarManuals.com

Timing Belt

Inspection

1. Remove the ignition coil covers and harness clamps.
2. Disconnect the connectors, then remove the ignition
coils.
3. Remove the cylinder head covers,
4. Inspect the timing belt for cracks and coolant or oil soaking.

NOTE:
Replace the belt if coolant or oil soaked.
Remove any oil or solvent that gets on the belt.

Inspect this area

for wear.

Rotate pulley and

Inspect belt.
Tension Adjustment

CAUTION:
Always adjust timing belt tension with the engine cold
Do not rotate the crankshaft when the adjusting bolt
is loose (the timing belt will skid over the teeth of
the rear intake caimshaft pulley).
Adjust the belt tension only when the belt has been
removed and reinstalled or replaced.

NOTE:
Tensioner is spring-loaded to apply proper tension to
the belt automatically after making the following ad-
justment. Inspect the timing belt before adjusting the belt
tension.
Always rotate the crankshaft clockwise. Rotating it
counterclockwise may result in improper adjustment
of the belt tension or cause the belt to jump a tooth
on the camshaft pulleys.
Install the timing beIt with the No. 1 piston at TDC
(see pages 6-18 ('91-'93) or ('94-'96),19 ('91-'93)
or ('94-'96) Remove the slack in the sequence of , and

by turning each camshaft pulley slightly.
Loosen the timing belt adjusting bolt 180° (the slack
at should be eliminated).

Then, tighten the timing belt adjusting bolt.

Verify that No. 1 piston is at TDC (see page 6-19).
Rotate the crankshaft clockwise nine teeth on the
camshaft pulley (The blue mark on the crankshaft pul- ley should line up with the pointer on lower cover).
Loosen
the
timing
belt
adjusting
bolt.

Retighten the adjusting bolt, torque to 43 N·m (4.3
kg-m, 31 Ib-fl).
Direction

of rotation

POINTER ON
LOWER COVER

ADJUSTING BOLT

43N·m (4.3 kg-m,

31 Ib-ft)
BLUE MARK
TDC MARK
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Rocker Arm s an d Los t Motio n Assemblie s
Inspection
NOTE: Whe n reassemblin g th e primar y rocke r arm , care -
full y appl y ai r pressur e t o th e oi l passag e o f th e rocke r
arm.
PRIMAR Y ROCKE R AR M
MI D ROCKE R AR M
SECONDAR Y
ROCKE R AR M
PISTON S
Inspect th e rocke r ar m pistons . Pus h the m manually .
— If the y d o no t mov e smoothly , replac e th e rocke r
ar m assembly .
PRIMARYMID
SECONDAR Y
Check pisto n movemen t
NOTE:
• Appl y oi l t o th e piston s whe n reassembling .
• Bundl e th e rocke r arm s wit h rubbe r band s t o
kee p the m togethe r a s sets . 2
. Remov e th e los t motio n assembl y fro m th e cylinde r
hea d an d inspec t it . Pushin g i t gentl y wit h th e finge r
wil l caus e i t t o sin k slightly . Increasin g th e forc e o n
i t wil l caus e i t t o sin k deeper .
— If th e los t motio n assembl y doe s no t mov e
smoothly , replac e it .
Pus h
LOS T MOTIO N ASSEMBL Y
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Valves, Valv e Spring s an d Valv e Seal s
Replacemen t
NOTE: Identif y valve s an d valv e spring s a s the y ar e re -
move d s o tha t eac h ite m ca n b e reinstalle d in it s origina l
position .
1. Usin g a n appropriate-size d socke t an d plasti c mallet ,
lightl y ta p th e valv e retaine r t o loose n th e valv e keep -
er s befor e installin g th e valv e sprin g compressor .
PLASTIC MALLE T
SOCKE T
2. Instal l th e sprin g compressor . Compres s th e sprin g
an d remov e valv e keeper .
VALVE SPRIN G
COMPRESSO R
ATTACHMENTEXTENSION07MAF-PR9010 A
VALVE SPRIN G
COMPRESSO R
ATTACHMENT07757 - PJ1010 A
VALVE SPRIN G COMPRESSO R(Commercially available )Snap-on CF71 1 o r equivalen t
3. Instal l th e specia l too l a s shown .
VALVE SEA L VALV
E GUID E SEA L REMOVE R
(Commerciall y available )
LISL E P/ N 5790 0 o r KD335 0
SEALPULLE R
4. Remov e th e valv e guid e seal .
VALV E GUID E SEA L REMOVE R
(Commerciall y available )
LISL E P/ N 5790 0 o r KD335 0
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Camshafts
Installation
17. Appl y liqui d gaske t t o th e hea d cove r gaske t a t th e
eigh t corner s o f th e recesses .
NOTE:
• Us e liqui d gasket , Par t No . 0871 8-0001 .
• Chec k tha t th e matin g surface s ar e clea n an d dr y
befor e applyin g liqui d gasket .
• D o no t instal l th e part s i f fiv e minute s o r mor e
hav e elapse d sinc e applyin g liqui d gasket . Instead ,
reapply liqui d gaske t afte r removin g ol d residue .
• Afte r assembly , wai t a t leas t 2 0 minute s befor e
filling th e engin e wit h oil .
Appl y liqui d gaske t t oth e shade d areas .
18. Whe n installin g th e cylinde r hea d cover , hol d th e
hea d cove r gaske t i n th e groov e b y placin g you r fin -
ger s o n th e camshaf t contactin g surface s (to p o f th e
semicircles) .
Once th e cylinde r hea d cove r i s o n th e cylinde r
head , slid e th e cove r slightl y bac k an d fort h t o sea t
th e hea d cove r gasket .
NOTE:
• Befor e installin g th e cylinde r hea d cover , clea n
th e cylinde r hea d contactin g surface s wit h a
sho p towel .
• D o no t touc h th e part s wher e liqui d gaske t wa s
applied .
• Replac e th e washe r whe n damage d o r deterio -
rated .
WASHE R
CYLINDE RHEAD COVE R
6 x 1. 0 m m12 N- m (1. 2 kg-m ,9 Ib-ft )
19. Tighte n th e nut s i n tw o o r thre e steps . I n th e fina l step ,
tighte n al l nuts , i n sequence , t o 1 2 N- m (1. 2 kg-m ,
9 Ib-ft) .
NOTE : Afte r assembly , wai t a t leas t 2 0 minute s
before fillin g th e engin e wit h oil .
20. Afte r installation , chec k tha t al l tubes , hose s an d
connector s ar e installe d correctly .
NOTE: Afte r installation , fil l th e engin e wit h oi l u p to
th e specifie d level , ru n th e engin e fo r mor e tha n thre e
minutes , the n chec k fo r oi l leakage .
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Exhaust Pip e an d Muffle r
Replacemen t
NOTE: Us e ne w gasket s an d self-lockin g nut s whe n reassembling .
GASKETSReplace.
JOINT PIP E
REA R SECONDAR YHO2S
4 5 N- m (4. 5 kg-m , 3 3 Ib-ft )
• B e carefu l no t t o
damage .
• Us e th e specia l too l
fo r remova l an d
installation . SELF-LOCKIN
G NUT S
10 x 1.2 5 mm34 N- m (3. 4 kg-m , 2 5 Ib-ft )Replace .
MUFFLE R
SELF-LOCKIN G NU T8 x 1.2 5 mm22 N- m (2. 2 kg-m ,16 Ib-ft )Replace .Tighten th e flang e nut s
i n steps , alternatin g
side-to-side .
THRE E WA Y CATALYTI C
CONVERTER S (TWCs )
Inspect a s show nbelow.
GASKET SReplace.
FRONT EXHAUST -
PIP E A FRON
T SECONDAR Y
HO2 S
4 5 N- m (4. 5 kg-m , 3 3 Ib-ft )
• B e carefu l no t t o
damage .
• Us e th e specia l too l
fo r remova l an d
installation .
JOINTPIPE
SELF-LOCKIN G NUT S10 x 1.2 5 mm55 N- m (5. 5 kg-m , 4 0 Ib-ft )
Replace . SELF-LOCKIN
G NUT S
8 x 1.2 5 mm22 N- m (2. 2 kg-m , 1 6 Ib-ft )Replace .Tighten th e flang e nut s i n steps ,
alternatin g side-to-side .
GASKETSReplace.
SELF-LOCKIN G NU T8 x 1.2 5 mm22 N- m (2. 2 kg-m , 1 6 Ib-ft )Replace .Tighten th e flang e nut s i n steps ,
alternatin g side-to-side .
6 x 1. 0 m m10 N- m (1. 0 kg-m , 7 Ib-ft )
TWC Inspection :
Using a flashlight , mak e a visua l chec k fo r plugging , meltin g
or crackin g o f th e catalyst .
TWC
FLASHLIGH T
REA
R EXHAUS T
PIP E A
GASKE TReplace .
GASKETReplace .
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CAUTION:

• Puncturing the insulation on a wire can cause poor or intermittent electrical connections.

• Bring the tester probe into contact with the terminal from the connector side of wire harness connectors in the engine

compartment. For female connectors, just touch lightly with the tester probe and do not insert the probe.

RUBBER SEAL
TESTER PROBE

WIRE HARNESS

TERMINALProCarManuals.com

PGM-FI Syste m
System Descriptio n
3. Fue l Cut-of f Contro l
• Durin g deceleratio n wit h th e throttl e valv e closed , curren t t o th e fue l injector s i s cu t of f t o improv e fue l econom y a t
speed s ove r 1,50 0 rpm .
• Fue l cut-of f actio n als o take s plac e whe n engin e spee d exceeds , 8,30 0 rpm , regardles s o f th e positio n o f th e throttl e
valve , t o protec t th e engin e fro m over-revving .
4 . A/ C Compresso r Clutc h Rela y
Whe n th e EC M receive s a deman d fo r coolin g fro m th e ai r conditionin g system , i t delay s th e compresso r fro m bein g
energized , an d enriche s th e mixtur e to assur e smoot h translatio n to th e A/ C mode .
5 . Evaporativ e Emissio n (EVAP ) Purg e Contro l Solenoi d Valv e
Whe n th e engin e coolan t temperatur e is belo w 153° F (67°C) , th e EC M control s th e EVA P purg e contro l solenoi d valv e
whic h cut s vacuu m to th e EVA P purg e contro l caniste r diaphragm .
6 . Intak e Ai r Bypas s (IAB ) Contro l Solenoi d Valv e
Whe n th e engin e spee d is belo w 4,80 0 rpm , th e IA B contro l solenoi d valv e is activate d b y a signa l fro m th e ECM . Intak e
ai r the n flow s throug h th e smalle r chamber , an d hig h torqu e is delivered . T o increas e ai r flo w a t engin e speed s highe r
tha n 4,80 0 rpm , th e solenoi d valv e is deactivate d b y th e ECM , an d th e intak e ai r flow s throug h th e large r chamber .
7 . Exhaus t Ga s Recirculatio n (EGR ) Contro l Solenoi d Valv e
Whe n th e EG R is require d fo r contro l o f oxide s o f nitroge n (NOx ) emissions , th e EC M supplie s groun d t o th e EG R
contro l solenoi d valv e whic h supplie s regulate d vacuu m to th e EG R valve .
EC M Fail-safe/Back-u p Function s
1 . Fail-Saf e Functio n
Whe n a n abnormalit y occur s i n a signa l fro m a sensor , th e EC M ignore s tha t signa l an d assume s a pre-programme d
valv e fo r tha t senso r tha t allow s th e engin e t o continu e t o run .
2 . Back-u p Functio n
Whe n a n abnormalit y occur s i n th e EC M itself , th e fue l injector s ar e controlle d b y a back-u p circui t independen t o f th e
syste m in orde r t o permi t minima l driving .
3 . Self-diagnosi s Functio n [Malfunctio n Indicato r Lam p (MIL) ]
Whe n a n abnormalit y occur s i n a signa l fro m a sensor , th e EC M light s th e MI L an d store s th e diagnosti c troubl e cod e
i n erasabl e memory . Whe n th e ignitio n i s initiall y turne d on , th e EC M supplie s groun d fo r th e MI L fo r tw o second s t o
chec k th e MI L bul b condition .
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Engine Control Module (ECM)

NOTE: If this symptom is intermittent, check for a loose No. 5 BACK-UP LIGHTS, ALTERNATOR,

TURN SIGNALS (15 A) fuse in the under-dash fuse/relay box, a poor connection at ECM terminal

A7, or an intermittent open in the BLU wire between the ECM (A7) and the gauge assembly.

Is the low oil pressure light on?

Try to start the engine.

Does the engine start?

Check for an open in the wire or

bulb:

1. Turn the ignition switch OFF.

2. Connect the ECM connector ter-

minal A7 to body ground with a

jumper wire.

3. Turn the ignition switch ON (II).

Is the MIL on?

Substitute a known-good ECM,

and recheck. If symptom/indica-

tion goes away, replace the origi-

nal
ECM.
— Repair short in the wire

between No. 5 BACK-UP

LIGHTS, ALTERNATOR, TURN

SIGNALS (15 A) fuse and

gauge assembly.

— Replace No. 5 BACK-UP

LIGHTS, ALTERNATOR, TURN

SIGNALS (15 A) fuse.

ECM CONNECTOR A (26P)

Check for an open in the wires

(PG line):

1. Turn the ignition switch ON (II).

2. Measure voltage between

body ground and ECM connec-

tor terminals A12 and A25 indi-

vidually.
WIRE SIDE OF FEMALE TERMINALS

Is there less than 1.0 V?
Repair open in the wire(s)

between ECM and G101 (located

at intake manifold) that had

more than 1.0V.

— Repair open in the wires

between ECM (A7) and gauge

assembly.

— Replace the MIL bulb.
WIRE SIDE OF FEMALE TERMINALS
ECM CONNECTOR A (26P)
Substitute a known-good ECM

and recheck. If symptom/indica-

tion goes away, replace the origi-

nal
ECM.
Turn the ignition switch ON (II).
The Malfunction Indicator Lamp

(MIL) never comes on (even for

two seconds) after ignition is

turned ON (II).ProCarManuals.com