1997 ACURA NSX sensor

Cylinder Heads

Illustrated Index

CAUTION: To avoid damage, wait until the engine coolant temperature drops below 100°F (38°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.

CAMSHAFT HOLDER

O-RING

Replace.
CAMSHAFT HOLDER

PLATE

CKP/CYP SENSOR

RUBBER SEALS

Replace when damaged

or deteriorated.

BACK COVER
Apply oil to the bolt threads.

FRONT INTAKE

CAMSHAFT

RUBBER SEALS

Replace for oil

leakage.

FRONT EXHAUST

CAMSHAFT

DOWEL PIN

CAMSHAFT PULLEY

(cont'd)ProCarManuals.com

Cylinder Heads

Installation (cont'd)

Rear:

8 x
1.25
mm

22 N-m (2.2 kgf-m,

16 Ibf-ft)
REAR PRIMARY

HEATED OXYGEN SENSOR

(REAR PRIMARY HO2S)

44 N-m (4.5 kgf-m,

33 Ibf-ft)

Be careful not to damage.

GASKET

Replace.

REAR EXHAUST

MANIFOLD

EXHAUST

MANIFOLD

COVER

SELF-LOCKING NUT

8 x
1.25
mm

30 N-m (3.1 kgf-m,

22 Ibf-ft)

Replace.

3. Install the cylinder heads on the engine block.

The cylinder head dowel pins and the head oil con-

trol orifice must be aligned.

• Always use a new cylinder head gasket.

• Clean the oil control orifice before installing.

CYLINDER HEAD

GASKET

Replace.
OIL CONTROL

ORIFICES

Clean.
CYLINDER HEAD

GASKET

Replace.

DOWEL PIN
DOWEL

PINS

O-RING

Replace.
4. Tighten the cylinder head bolts sequentially in two

or three steps.

• Apply clean engine oil to the bolt threads and

washer contact surfaces.

Specified Torque

M/T:
11 x 1.5 mm

96 N-m (9.8 kgf-m, 71 Ibf ft)

A/T:
11 x 1.5 mm

76 N-m (7.8 kgf-m, 56 Ibf ft)

NOTE: We recommend using a beam-type torque

wrench. When using a preset-type torque wrench,

be sure to tighten slowly and not to over-tighten.

CYLINDER HEAD BOLTS TORQUE SEQUENCE

CYLINDER HEAD BOLT

M/T:
11 x 1.5 mm

96 N-m (9.8 kgf-m, 71 Ibf-ft)

A/T:
11 x 1.5 mm

76 N-m (7.8 kgf-m, 56 Ibf-ft)

Apply clean engine oil to the

bolt threads and washer contact

surfaces.ProCarManuals.com

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 .
M/T:
REAR SECONDARY HEATEDOXYGEN SENSOR (REARSECONDARY HO2S )
4 4 N- m (4.5 kgf-m , 3 3 Ibf-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 . LON
G BOL T
8 x 1.2 5 mm22 N- m (2. 2 kgf-m , 1 6 Ibf-ft )Replace .Tighten th e flang e bolts in steps ,
alternatin g side-to-side .
MUFFLER
SHORT BOL T8 x 1.2 5 mm22 N- m (2. 2 kgf-m ,16 Ibf-ft )Replace .Tighten th e flang e bolt s
i n steps , alternatin g
side-to-side .
GASKETReplace .
FRON T THRE E WA Y
CATALYTI C CONVERTE R(TWOInspectio n a s show n
pag e 9-7.GASKE TReplace .
REAR TW CInspectio n a s show n
page 9-7. REA
R SECONDAR Y
HEATED OXYGE NSENSOR (REA RSECONDAR Y HO2S )44 N-m (4.5 kgf-m,33 Ibf-ft)• B e carefu l no t t o
damage .
• Us e th e specia l too lfor remova l an dinstallation .
6 x 1. 0 m m9.8 N- m (1. 0 kgf-m ,
7. 2 Ibf-ft )
GASKET SReplace.
LON G BOL T
8 x 1.2 5 mm22 N- m (2. 2 kgf-m , 1 6 Ibf-ft )Replace .Tighten th e flang e bolt s i n steps ,
alternatin g side-to-side .
ProCarManuals.com

Component Location s
Index
THROTTL E POSITIO N (TP ) SENSO R
FUE L TAN K
PRESSUR E SENSO R
EVAPORATIV E
EMISSIO N (EVAP )
CONTRO L CANISTE R
VEN T SHU T VALV E EXHAUS
T GA S RECIRCULATIO N (EGR ) VALV E
an d LIF T SENSO R
ENGIN E COOLAN T TEMPERATUR E (ECT ) SENSO R
INTAK E AI R TEMPERATUR E (IAT ) SENSO R
CRANKSHAF T POSITION /
CYLINDE R POSITIO N
(CKP/CYP ) SENSO R
FUEL PUM P RESISTO R
Troubleshooting , pag e 11-14 1
FUE L
INJECTO R
RESISTO R (A/T )
Testing ,page 11-13 6
EVAPORATIV
E EMISSIO N
(EVAP ) PURG E CONTRO L
SOLENOI D VALV E
EVAPORATIV E
EMISSION(EVAP) BYPAS S
SOLENOI D
VALV E
EVAPORATIV E EMISSIO N(EVAP) TW O WA Y VALV ETesting , pag e 11-17 8
CONTRO L BO X
page , 1 1 -8 THROTTL E VALV E
CONTRO L MOTO R
NEUTRA L SWITC H (M/T )
Troubleshooting , pag e 11-12 4
REVERS E LOCKOU T
SOLENOI D VALV E (M/T )
FRON T KNOC K SENSO R (KS2 ) SPAR
K PLU G VOLTAG E
DETECTIO N MODUL E
FRON T PRIMAR Y HEATE D
OXYGEN SENSOR (HO2S )
(BAN K 2 , SENSO R 1 )
SPAR K PLU G VOLTAG E SENSO R(built int o th e IGNITIO N COI LAssy. )
FRONT SECONDAR Y HEATE D OXYGE N
SENSO R (HO2S ) (BAN K 2 , SENSO R 2 )
REAR SECONDARY HEATED OXYGEN SENSOR (HO2S) (BANK 1, SENSOR 2)
REA R KNOC K SENSO R (KS1 )
REAR PRIMAR Y HEATE DOXYGEN SENSO R (HO2S )
(BAN K 1 , SENSO R 1 )
(cont'd )
For Troubleshooting of DTC related components, see chart on page 11-52.
ProCarManuals.com

FRONT PRIMAR Y HEATE D OXYGE N SENSO R (HO2S )
(BAN K 2 , SENSO R 1 )
REA R PRIMAR Y HEATE D OXYGE N SENSO R (HO2S )
(BAN K 1 , SENSO R 1 )
FRON T SECONDAR Y HEATE D OXYGE N SENSO R (HO2S )
(BAN K 2 , SENSO R 2 )
REAR SECONDARY HEATED OXYGEN SENSOR (HO2S)
(BANK 1, SENSOR 2)
MANIFOL D ABSOLUT E PRESSUR E (MAP ) SENSO R
ENGIN E COOLAN T TEMPERATUR E (ECT ) SENSO R
INTAK E AI R TEMPERATUR E (IAT ) SENSO R
FRON T KNOC K SENSO R (KS2 )
REA R KNOC K SENSO R (KS1 )
AI R CLEANE R (ACL )
FUE L INJECTO R
FUE L PRESSUR E REGULATO R
FUE L FILTE R
FUE L PUM P (FP )
FUE L TAN K
FUE L TAN K EVAPORATIV E EMISSIO N (EVAP ) VALV E
INTAK E AI R BYPAS S (IAB ) CHEC K VALV E
INTAK E AI R BYPAS S (IAB ) VACUU M TAN K
INTAK E AI R BYPAS S (IAB ) CONTRO L SOLENOI D VALV E INTAK
E AI R BYPAS S (IAB ) CONTRO L DIAPHRAG M
FRON T THRE E WA Y CATALYTI C CONVERTE R (TW O
REA R THRE E WA Y CATALYTI C CONVERTE R (TW O
POSITIV E CRANKCAS E VENTILATIO N (PCV ) VALV EEXHAUS T GA S RECIRCULATIO N (EGR ) VALV E
EXHAUS T GA S RECIRCULATIO N (EGR ) VALV E LIF T SEN -
SOREXHAUS T GA S RECIRCULATIO N (EGR ) VACUU M CONTRO LVALVEEXHAUS T GA S RECIRCULATIO N (EGR ) CONTRO L
SOLENOI D VALV E
EVAPORATIV E EMISSIO N (EVAP ) CONTRO L CANISTE R
EVAPORATIV E EMISSIO N (EVAP ) PURG E CONTRO L
SOLENOI D VALV E
EVAPORATIV E EMISSIO N (EVAP ) CONTRO L CANISTE R
VEN T SHU T VALV E
EVAPORATIV E EMISSIO N (EVAP ) BYPAS S SOLENOI D
VALVEEVAPORATIV E EMISSIO N (EVAP ) TW O WA Y VALV E
FUE L TAN K PRESSUR E SENSO R
THROTTL E BOD Y (TB )
RESONATO R
ProCarManuals.com

Troubleshooting

Troubleshooting Procedures (cont'd)

ECM Data

By connecting the OBD II scan tool or the Honda PGM Tester to the 16P data link connector (DLC), various data can be

retrieved from the ECM. The items listed in the table below conform to the SAE recommended practice.

The Honda PGM Tester also reads data beyond that recommended by SAE.

Understanding this data will help to find the causes of intermittent failures or engine problems.

NOTE:

The "operating values" given below are approximate values and may be different depending on the environment and

the individual vehicle.

Unless noted otherwise, "at idle speed" means idling with the engine completely warmed up, A/T in or position,

M/T in neutral, and the A/C and all accessories turned off.

Data
Description
Operating Value

Freeze Data

Diagnostic

Trouble Code

(DTC)
If the ECM detects a problem, it will store it as a code

consisting of one letter and four numbers.

Depending on the problem, an SAE-defined code

(POxxx)
or a
Honda-defined code
(P1xxx)
will
be
output

to the tester.
If no problem is detected,

there is no output.

YES

Engine Speed
The ECM computes engine speed from the signals sent

from the Crankshaft Position sensor.

This data is used for determining the time and amount

of fuel injection.
Nearly the same as

tachometer indication at

idle speed:

A/T:
780 ± 50 rpm

M/T:
800 ± 50 rpm
YES

Vehicle Speed
The ECM converts pulse signals from the Vehicle

Speed Sensor (VSS) into speed data.
Nearly the same as

speedometer indication
YES

Manifold

Absolute

Pressure (MAP)
The absolute pressure created in the intake manifold by

engine load and speed.
With engine stopped:

Nearly the same as atmo-

spheric pressure at idle

speed:

24-37kPa(180-280

mmHg, 7.1-11.0 inHg)
YES

Engine Coolant

Temperature

(ECT)
The ECT sensor converts coolant temperature into volt-

age and signals the ECM. The sensor is a thermistor

whose internal resistance changes with coolant tem-

perature. The ECM uses the voltage signals from the

ECT sensor to determine the amount of injected fuel.
With cold engine:

Same as ambient temper-

ature and IAT

With engine warmed up:

approx. 176-194°F

(80 - 90°C)
YES

Heated Oxygen

Sensor (HO2S)

(Bank 1, Sensor 1)

(Bank 1, Sensor 2)

(Bank 2, Sensor 1)

(Bank 2, Sensor 2)
The Heated Oxygen Sensor detects the oxygen content

in the exhaust gas and sends voltage signals to the

ECM. Based on these signals, the ECM controls the

air/fuel ratio. When the oxygen content is high (that is,

when the ratio is leaner than the stoichiometric ratio),

the voltage signal is lower. When the oxygen content is

low (that is, when the ratio is richer than the stoichio-

metric ratio), the voltage signal is higher.
0.0-1.25V

At idle speed:

about 0.1-0.9V

NOProCarManuals.com

DataDescriptio nOperating Valu eFreez e Dat a
HO2 S
Feedbac k
Loop Statu s
(Bank 1 : Rear )
(Bank 2 : Front )
Loop statu s i s indicate d a s "open " o r "closed" .
Closed : Base d o n th e H02 S output , th e EC M deter -
mine s th e air/fue l rati o an d control s th e amoun t o f
injecte d fuel .
Open : Ignorin g H02 S output , th e EC M refer s t o signal s
fro m th e TP , MAP , an d EC T sensor s to contro l th e
amoun t o f injecte d fuel . A
t idl e speed : close d
YES
Shor t Ter m
Fue l Tri m
(Ban k 1 : Rear )
(Bank 2 : Front ) Th
e air/fue l rati o correctio n coefficien t fo r correctin g
th e amoun t o f injecte d fue l whe n HO2 S feedbac k is in
th e close d loo p status . Whe n th e signa l fro m th e HO2 S
i s weak , shor t ter m fue l tri m get s higher , an d th e EC M
increase s th e amoun t o f injecte d fuel . Th e air/fue l rati o
graduall y get s richer , causin g a highe r H02 S output .
Consequently , th e shor t ter m fue l tri m is lowered , an d
th e EC M reduce s th e amoun t o f injecte d fuel . Thi s
cycl e keep s th e air/fue l rati o clos e to th e stoichiometri c
rati o whe n in close d loo p status .
-30%-+43 %
YES
Lon g Ter m
Fue l Tri m
(Ban k 1 : Rear )
(Bank 2 : Front )
Long ter m fue l tri m in compute d fro m shor t ter m fue l
tri m an d indicate s change s occurin g in th e fue l suppl y
syste m ove r a lon g period .
I f lon g ter m fue l tri m is highe r tha n 1.00 , th e amoun t o f
injecte d fue l mus t b e increased . I f i t i s lowe r tha n 1.00 ,
th e amoun t o f injecte d fue l mus t b e reduced .-19%-+25 %
YES
Intak e Ai r
Temperatur e
(IAT)
The IA T senso r convert s intak e ai r temperatur e int o
voltag e an d signal s th e ECM . Whe n intak e ai r tempera -
tur e is low , th e interna l resistanc e o f th e senso r
increases , an d th e voltag e signa l i s higher . Wit
h col d engine :
Sam e a s ambien t temper -
atur e an d EC T
YES
Throttl e
Positio n Base
d o n th e accelerato r peda l position , th e openin g
angl e o f th e throttl e valv e is indicated .At idle : Approx . 10 %
At ful l throttle : Approx .
90%
YE S
Ignitio n
Timing
The ignitio n advanc e angl e is se t b y th e ECM . Th e EC M
matche s ignitio n timin g t o th e drivin g conditions .A
t idl e speed : 1 5 ±2°
BTD C wit h th e SC S servic e
connecto r connected .
NO
Calculate d
Load Valu e
(CLV )
CLV is th e engin e loa d calculate d fro m th e MA P data . At idl e speed :
15-35%
At 2,50 0 rp m wit h n o load :
12-30 %
YES
ProCarManuals.com

Troubleshooting

Engine Control Module Terminal Arrangement

ECM CONNECTOR A (26P)

ECM CONNECTOR A (26P)
Wire side of female terminals

NOTE: Standard battery voltage is 12 V.

Terminal

number

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

20

21

22

23

24

25

26
Wire

color

BRN

RED

BLU

BLK/YEL

GRN/BLK

GRN

BLU

RED/BLU

GRY

LTGRN

PNK

BLK

YEL/BLK

YEL

BLK/RED

WHT/BLU

ORN

PNK/BLU

RED/YEL

GRN/RED

ORN/BLK

BRN

BLK

BRN/BLK
Terminal name

INJ1 (No. 1 FUEL INJECTOR)

INJ2 (No. 2 FUEL INJECTOR)

INJ3 (No. 3 FUEL INJECTOR)

VSV (EVAP CONTROL CANIS-

TER VENT SHUT VALVE)

FLR1 (FUEL PUMP RELAY)

ESOL (EGR CONTROL

SOLENOID VALVE)

MIL (MALFUNCTION

INDICATOR LAMP)

ACC (A/C CLUTCH RELAY)

FS02SHTC (FRONT SEC-

ONDARY HEATED OXYGEN

SENSOR HEATER CONTROL)

RS02SHTC (REAR SEC-

ONDARY HEATED OXYGEN

SENSOR HEATER CONTROL)

IGN COIL1 (No. 1 IGNITION

COIL part of IGNITION

CONTROL MODULE)

PG1 (POWER GROUND)

IGP1 (POWER SOURCE)

INJ4 (No. 4 FUEL INJECTOR)

INJ5 (No. 5 FUEL INJECTOR)

INJ6 (No. 6 FUEL INJECTOR)

2WBS (EVAP BYPASS

SOLENOID VALVE)

IABCS (IAB CONTROL

SOLENOID VALVE)

PCS (EVAP PURGE CONTROL

SOLENOID VALVE)

FP02SHTC (FRONT PRIMARY

HEATED OXYGEN SENSOR

HEATER CONTROL)

RP02SHTC (REAR PRIMARY

HEATED OXYGEN SENSOR

HEATER CONTROL)

IGN COIL2 (No. 2 IGNITION

COIL part of IGNITION

CONTROL MODULE)

PG2 (POWER GROUND)

LG1 (LOGIC GROUND)
Description

Drives No. 1 fuel injector

Drives No. 2 fuel injector

Drives No. 3 fuel injector

Drives EVAP control canister vent

shut valve

Drives fuel pump relay

Drives EGR control solenoid

valve

Drives MIL

Drives A/C clutch relay

Drives front secondary heated

oxygen sensor heater

Drives rear secondary heated

oxygen sensor heater

Sends ignition pulse

Ground for the ECM power circuit

Power source for the ECM control

circuit

Drives No. 4 fuel injector

Drives No. 5 fuel injector

Drives No. 6 fuel injector

Drives EVAP bypass solenoid

valve

Drives IAB control solenoid valve

Drives EVAP purge control

solenoid valve

Drives front primary heated

oxygen sensor heater

Drives rear primary heated

oxygen sensor heater

Sends ignition pulse

Ground for the ECM power circuit

Ground for the ECM control

circuit
Signal

With engine running: pulses

With ignition switch ON (II):

battery voltage

0 V for two seconds after turning ignition

switch ON (II), then battery voltage

With EGR operating during driving with

fully warmed up engine: duty controlled

With EGR not operating: battery voltage

With MIL turned ON: 0V

With MIL turned OFF: battery voltage

With compressor ON: 0 V

With compressor OFF: battery voltage

With ignition switch ON (II): battery

voltage

With fully warmed up engine running: 0 V

With ignition switch ON: battery voltage

With fully warmed up engine running:

pulses

With ignition switch ON (II): 0 V

With engine running: pulses

Less than 1.0 V at all times

With ignition switch ON (II): battery voltage

With ignition switch OFF: 0 V

With engine running: pulses

With ignition switch ON (II): battery

voltage

With engine speed below 4,800 rpm:

battery voltage

With engine speed above 4,800 rpm: 0 V

With engine running, engine coolant

below 153°F (67°C): battery voltage

With engine running, engine coolant

above 153°F (67°C): 0 V

With ignition switch ON (II): battery

voltage

With fully warmed up engine running: 0 V

With ignition switch ON (II): battery

voltage

With fully warmed up engine running: 0 V

With ignition switch ON (II): 0 V

With engine running: pulses

Less than 1.0 V at all times

Less than 1.0 V at all timesProCarManuals.com