1991 ACURA NSX low oil pressure

9. Relieve fuel pressure by loosening the service bolt
on the fuel filter about one turn (see section 11).
Do not smoke while working on the
fuel
system.
Keep open flame away from work
area. Drain fuel only into an approved container.
10. Remove the fuel feed pipe and fuel return hose.
11. Remove the wire harness cover, then remove the fuel pipe clamp.

22 N·m
(2.2 kg-m,
16 Ib-ft)

WIRE HARNESS

COVER
6 x 1.0 mm

12 N·m
(1.2 kg-m,

9 lb-ft)

FUEL FEED
PIPE

WASHERS
Replace.

FUEL RETURN

HOSE

12. Remove the brake booster vacuum hose and evapo- rative emission (EVAP) control canister hose.

BRAKE BOOSTER

VACUUM HOSE

EVAP CONTROL

CANISTER HOSE
13. Remove the expansion tank cap.

14. Raise the hoist to full height.
15. Drain the engine coolant (see page
10-5).
Loosen the drain plug from the radiator lower
tank. Remove two drain bolls from the water pipes.
Reinstall the drain bolts with new washers.
Loosen the front and rear engine drain bolts to
drain engine coolant from the cylinder heads.
Connect rubber hoses to the drain bolts.
16. Drain the transmission oil/fluid. Reinstall the drain plug with a new washer.
17. Drain the engine oil. Reinstall the drain plug with a
new washer.

18. Lower the hoist, then remove the air cleaner hous-

ing (see page 6-25 ('91-'93 Mode ls),or('95-'96 Models).

19. Disconnect two hoses, then remove the expansion

tank.

6 x 1.0 mm

10 N·m
11.0 kg-m,

7 lb-ft)

EXPANSION

TANK

WATER BYPASS

HOSES
(cont'd)ProCarManuals.com

Cylinder Heads

Illustrated Index (cont'd)
CAUTION:
To
avoid
damage,
wait
until
the
engine
coolant
temperature
drops
below
100°F
(39-C]
before
removing
the
cylin-

der head.

NOTE: Use new O-rings and gaskets when reassembling.

Prior to reassembling, clean all the parts in solvent, dry them, and apply lubricant to any contact parts.

REAR VARIABLE VALVE TIMING
AND VALVE LIFT ELECTRONIC CONTROL
SYSTEM (VTEC) SOLENOID VALVE

Troubleshooting, page 6-3 ('91-'93) or ('94-'96)

EXHAUST GAS
RECIRCULATI0N (EGR) VALVE

6 x 1 .0 mm
12 N·m
(1.2 kg-m.
9 Ib-ft)
8 x
1.25
mm

22 N·m
(2.2 kg-m,
16 Ib-ft)
ENGINE COOLANT
TEMPERATURE (ECT) SENSOR
18 N·m (1.8 kg-m, 13 Ib-ft)

8 x
1.25
mm
22 N·m (2.2 kg-m. 16 lb-ft)
FRONT VTEC SOLENOID VALVE

Troubleshooting. page 6-3

SEALING BOLTS

60 N·m
(6.0 kg-m,

43 lb-ft)

OIL PRESSURE

GAUSE SENDING
UNIT (section 23)

ROCKER

SHAFTS
WASHERS
Replace.

8 x
1.25
mm

22 N·m
(2.2 kg-m,16 Ib-ft)
DOWEL PIN

0-RING

Replace.

ECT SWITCH

28 N·m
12.8 kg-m.

20 lb-ft

O-RING

Replace.

O-RING

Replace.

ROCKER ARM ASSEMBLY[PRIMARY. MID, SECONDARY]

Inspection, page 6-32 ('91-'93) or ('94-'96)

ROCKER SHAFT

OIL CONTROL
ORIFICE

Remove with 5 mm

boit and clean.

FILTER
Replace.

GASKET

Replace.

O-RING

Replace.ProCarManuals.com

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

A/C Servic e Tip s an d Precaution s
The ai r conditionin g syste m use s HFC-134 a (R-134a ) refrigeran t an d polyalkyleneglyco l (PAG ) refrigeran t oi l (ND-OI L
8 : P/ N 38899-PR7-A01) , whic h ar e no t compatibl e wit h CFC-1 2 (R-12 ) refrigeran t an d minera l oil . D o no t us e R-1 2 refriger -
an t o r minera l oi l i n thi s system , an d d o no t attemp t t o us e R-1 2 servicin g equipment ; damag e t o th e ai r conditionin g
system o r you r servicin g equipmen t wil l result .
Only us e servic e equipmen t tha t i s U.L.-liste d an d i s certifie d t o mee t th e requirement s o f SA E J221 0 t o remov e R-134a;
fro m th e ai r conditione r system .
CAUTION : Exposur e to ai r conditione r refrigeran t an d lubrican t vapo r o r mis t ca n irritat e eyes , nos e an d throat , Avoi d
breathin g th e ai r conditione r refrigeran t an d lubrican t vapo r o r mist .
I f accidenta l syste m discharg e occurs , ventilat e wor k are a befor e resumin g service .
R-134 a servic e equipmen t o r vehicl e ai r conditione r system s shoul d no t b e pressur e teste d o r lea k teste d wit h compresse d
air.
Som e mixture s o f ai r an d R-134 a hav e bee n show n to b e combustibl e elevate d pressure s an d ca n resul t
i n fir e o r explosio n causin g injur y o r propert y damage . Neve r us e compresse d ai r t o pressur e tes t R-134 a servic e
equipmen t o r vehicl e ai r conditionin g systems .
Additiona l healt h an d safet y informatio n ma y b e obtaine d fro m th e refrigeran t an d lubrican t manufacturers .
1 . Alway s disconnec t th e negativ e cabl e fro m th e batter y wheneve r replacin g ai r conditionin g parts .
2 . Kee p moistur e an d dus t ou t o f th e system . Whe n disconnectin g an y lines , plu g o r cap the fitting s immediately ; don' t
remov e th e cap s o r plug s unti l jus t befor e yo u reconnec t eac h line .
3 . Befor e connectin g an y hos e o r line , appl y a fe w drop s o f refrigeran t oi l (ND-OI L 8 ) t o th e O-ring .
4. Whe n tightenin g o r loosenin g a fitting , us e a secon d wrenc h t o suppor t th e matchin g fitting .
5. Whe n recoverin g th e system , us e a R-134 a refrigeran t Recovery/Recycling/Chargin g System ; don' t releas e
refrigeran t int o th e atmosphere .
6 . Ad d refrigeran t oi l (ND-OI L 8 ) afte r replacin g th e followin g parts :
NOTE:
• D o no t retur n th e oi l t o th e containe r onc e dispense d an d neve r mi x wit h othe r refrigeran t oil s t o avoi d
contamination .
• Immediatel y afte r usin g th e oil , replac e th e ca p o n th e containe r an d sea l i t t o avoi d moistur e absorption .
• D o no t spil l th e refrigeran t oi l o n th e car ; i t ma y damag e th e paint ; i f th e refrigeran t oi l contact s th e paint , was h i t
of f immediately .
Condenser ........................ . 10 c c (1/ 3 fl oz )
Evaporato r ........................ . 1 0 c c (1/ 3 f l oz )
Lin e o r hos e ....................... . 2 0 c c (2/ 3 f l oz )
Receive r ........................... . 1 0 c c (1/ 3 f l oz )
Compresso r ....................... . O n compresso r
replacement , subtrac t th e volum e o f oi l drain -
e d fro m th e remove d compresso r fro m 14 0 c c
(4-2/ 3 f l oz) , an d drai n th e calculate d volum e
o f oi l fro m th e ne w compressor : 14 0 c c (4-2/ 3
f l oz ) — Volum e o f oi l fro m remove d com -
presso r = Volum e t o drai n fro m ne w com -
pressor .
CORROSIO N RESISTAN T BOL T
Suctio n hos e an d discharg e hos eto A/ C line s ..................... . 2 2 N- m (2. 2 kg-m , 1 6 Ib-ft )Discharg e lin e C(bot h sides ) ..................... . 2 3 N- m (2. 3 kg-m , 1 7 Ib-ft )Condense r lin e A(bot h sides ) ..................... . 2 3 N- m (2. 3 kg-m , 1 7 Ib-ft )Condense r lin e C to lef t sid econdense r ....................... . 1 4 N- m (1. 4 kg-m , 1 0 Ib-ft )Receiver/drye r ................. . 1 4 N- m (1. 4 kg-m , 1 0 Ib-ft )
Receive r lin e an d suctio n lin e t o heate rassembl y ........................ . 2 2 N- m (2. 2 kg-m , 1 6 Ib-ft )Compresso r hos e mountin gbolts .............................. . 2 2 N- m (2. 2 kg-m , 1 6 Ib-ft )Compresso r mountin gbolts .............................. . 2 5 N- m (2. 5 kg-m , 1 8 Ib-ft )Compresso r bracke tmountin g bolt s ................ . 5 0 N- m (4. 5 kg-m , 3 6 Ib-ft )Idler pulle y cente r nu t ....... . 4 5 N- m (4. 5 kg-m , 3 3 Ib-ft )6 m m bol t ................... . 1 0 N- m (1. 0 kg-m , 7 Ib-ft )
ProCarManuals.com

Recovery

Only use service equipment that is U.L.-listed and is cer-

tified to meet the requirements of SAE J2210 to remove

HFC-134a (R-134a) from the air conditioning system.

CAUTION: Exposure to air conditioner refrigerant

and lubricant vapor or mist can irritate eyes, nose

and throat. Avoid breathing the air conditioner

refrigerant and lubricant vapor or mist.

If accidental system discharge occurs, ventilate work

area before resuming service.

R-134a service equipment or vehicle air conditioning sys-

tem should not be pressure tested or leak tested with

compressed air.

Some mixtures of air and R-134a have

been shown to be combustible at elevated pressures

and can result in fire or explosion causing injury or

property damage. Never use compressed air to pres-

sure test R-134a service equipment or vehicle air

conditioning systems.

Additional health and safety information may be obtained

from the refrigerant and lubricant manufactures.

1. Connect a R-134a refrigerant Recovery/Recycl-

ing/Charging System to the car as shown following

the equipment manufacturer's instructions.

2. Measure the amount of refrigerant oil removed

from the A/C system after the recovery process is

completed.

NOTE: Be sure to install the same amount of new

refrigerant oil back into the A/C system before

charging.
Recovery/Recycling/Charging System.ProCarManuals.com

Gauge Assembly

Bulb Locations

GAUGE LIGHTS (1.4W x 2)

SRS INDICATOR LIGHT (1.4 W)

RIGHT TURN SIGNAL INDICATOR LIGHT (1.4 W)

EPS INDICATOR LIGHT (1.4 W)

BRAKE SYSTEM LIGHT (1.4 W)

SEAT BELT REMINDER LIGHT (1.4 W)

TCS INDICATOR

LIGHT (1.96 W)

LOW FUEL INDICATOR

LIGHT (1.4 W)

GAUGE LIGHT

(1.4
W)
HIGH BEAM INDICATOR LIGHT (1.4 W)

LEFT TURN SIGNAL INDICATOR LIGHT (1.4 W)

ABS

INDICATOR LIGHT (1.4 W)

CHARGING SYSTEM LIGHT (1.4 W)

MALFUNCTION

INDICATOR

LAMP (MIL)

(1.4W)

LOW OIL PRESSURE

INDICATOR

LIGHT (1.4 W)

GAUGE LIGHT

(1.4
W)

GAUGE LIGHT

(3.0
W)
GAUGE LIGHT

(3.0
W)
GAUGE LIGHT

(3.0
W)
CRUISE INDICATOR LIGHT

(1.96
W)ProCarManuals.com

14. Relieve fuel pressure (see section 11).
Do not smoke while working on fuel
system; keep open flame or spark away from work
area. Drain fuel only into an approved container.
1 5. Disconnect the fuel feed pipe and the return hose
(page 5-21).

16. Remove the ignition coil covers, the wire harness covers, the ignition coils and the connectors (page
6-23).
17. Remove the water hoses, then remove the expan- sion tank (page 5-21).
18. Remove the breather hose, and the air cleaner housing (page 5-22).
19. Remove the brake booster hose, the evaporative emission (EVAP) control canister hose and other
hoses from the intake manifold and throttle body
(page 5-22).
20. Remove the emission control box (page 5-23). Do not disconnect emission hose.Disconnect the three connectors before
removing.
21. Remove the connector, the terminal and the alternator.
22. Disconnect the following engine wire harness con- nectors, then remove the harness clamps from thecylinder head and the intake manifold.
Front cylinder head:

Crankshaft position (CKP)/cylinder position
(CYP) sensor connector
Air conditioning (A/C) compressor magnetic clutch connector
Heated oxygen sensor (H02S) connector
Ground cable terminals Three injector connectors (cylinders No. 4, 5

and 6)

Intake air temperature (IAT) sensor connector
Ignition control module (ICM) connector
Condenser connector

Engine oil pressure gauge sending unit

connector

VTEC solenoid valve connector
VTEC pressure switch connector
Engine coolant temperature (ECT) sensor

connector
ECT sending unit connector
Accelerator pedal opening sensor connector

(throttle body)

Radiator fan control sensor connector
Rear cylinder head: Engine oil pressure switch connector (oil cooler

base)

Heated oxygen sensor connector
Three injector connectors (cylinders No. 1, 2

and 3)
Idle air control (IAC) valve connector
Knock sensor connector
Throttle actuator motor connector

Throttle position sensor connector

VTEC solenoid valve connectorVTEC pressure switch connector
ICM connector

Ground terminal

ICM CONNECTORS THROTTLE ACTUATOR

MOTOR CONNECTOR

THROTTLE POSITION
SENSOR CONNECTOR
ACCELERATOR PEDAL OPENING
SENSOR CONNECTORProCarManuals.com

Troubleshooting Flowchart

Engine Control Module (ECM)
Malfunction Indicator Lamp (MIL)
never comes on (even for two se-
conds) after ignition is turned on.
Is the low oil pressure light on?

Turn the ignition switch OFF.

Connect the test harness between
the ECM and connectors (see page 11-37).
Connect A13 terminal to body
ground.

Turn the ignition switch ON.
Is the MIL on?

Measure voltage between body
ground and the following termi-
Is there less than 1.0 V?
Substitute a known-good ECM
and recheck. If symptom/indica-
tion goes away, replace the origi-

nal
ECM. Inspect No. 5 (10 A) fuse in the
under-dash fuse box.
Is the fuse OK?
Repair open in YEL wire between
No. 5 (10 A) fuse and gauge as-

sembly.

Replace the MIL bulb.
Repair open in BLU wire be-
tween ECM (A13) and gauge

assembly.

Repair open in wire between ECM
and G101 (located at right middle of engine) that had more than 1.0

V.
Replace the fuse.
G101
(cont'd)

nals individually:

A23,
A24,

A26,
B2.ProCarManuals.com