1997 ACURA NSX service

A/T:

Intake Valve Dimensions

A Standard (New): 34.9 - 35.1 mm

(1.374 - 1.382 in)

B Standard (New):

C Standard (New):

C Service Limit:

D Standard (New):

D Service Limit:
111.10-111.40 mm

(4.374 - 4.386 in)

5.475-5.485 mm

(0.2156-0.2159 in)

5.445 mm (0.2144 in)

1.05—1.35 mm

(0.041-0.053 in)

0.85 mm (0.033 in)

Exhaust Valve Dimensions

A
Standard (New):
29.9-30.1
mm

(1.177-1.185 in)

109.60-109.90
mm

(4.315-4.327 in)

5.45-5.46
mm

(0.2146-0.2150 in)

5.42 mm (0.2134 in)

1.65-1.95
mm

(0.065-0.077 in)

1.45 mm (0.057 in)
B Standard (New):

C Standard (New):

C Service Limit:

D Standard (New):

D Service Limit:ProCarManuals.com

Valve Guides

Valve Movement

Measure the guide-to-stem clearance with a dial indicator

while rocking the stem in the direction of normal thrust

(wobble method).

Intake Valve Stem-to-Guide Clearance:

Standard (New): 0.05 — 0.11 mm

(0.002 — 0.004 in)

Service Limit: 0.16 mm (0.006 in)

Exhaust Valve Stem-to-Guide Clearance:

Standard (New): 0.10 — 0.16 mm

(0.004 — 0.006 in)

Service Limit: 0.22 mm (0.009 in)

Valve extended 10 mm out from seat.

If measurement exceeds the service limit, recheck

using a new valve.

If measurement is now within the service limit,

reassemble using a new valve.

If measurement still exceeds limit, recheck using

alternate method below, then replace valve and

guide, if necessary.
NOTE: An alternate method of checking guide to

stem clearance is to subtract the O.D. of the valve

stem, measured with a micrometer, from the I.D. of

the valve guide, measured with an inside microme-

ter or ball gauge.

Take the measurements in three places along the

valve stem and three places inside the valve guide.

The difference between the largest guide measure-

ment and the smallest stem measurement should

not exceed the service limit.

Intake Valve Stem-to-Guide Clearance:

Standard (New): 0.025 — 0.055 mm

(0.001 — 0.002 in)

Service Limit: 0.08 mm (0.003 in)

Exhaust Valve Stem-to-Guide Clearance:

Standard (New): 0.05 — 0.08 mm

(0.002 — 0.003 in)

Service Limit: 0.11 mm (0.004 in)ProCarManuals.com

Piston/Connecting Rod

Assemblies

Inspection

1. Check the piston for distortion or cracks.

NOTE: If cylinder is bored, an oversized piston

must be used.

2. Measure piston diameter at a point 17 mm (0.67 in)

from the bottom of the skirt.

NOTE: There are two standard-size pistons (A =

no letter and B). The letter is stamped on the top of

the piston. These letters are also stamped on the

block as cylinder bore sizes.

M/T:

Piston A (no letter) Diameter

Standard (New): 92.990 - 93.003 mm

(3.6610-3.6615 in)

Service Limit: 92.97 mm (3.6602 in)

Piston B Diameter

Standard (New): 92.980 - 92.993 mm

(3.6606-3.6611 in)

Service Limit: 92.96 mm (3.6598 in)

A/T:

Piston A (no letter) Diameter

Standard (New): 89.986 - 90.004 mm

(3.5427 - 3.5435 in)

Service Limit: 89.97 mm (3.5421 in)

Piston B Diameter

Standard (New): 89.976 - 89.994 mm

(3.5424 - 3.5431 in)

Service Limit: 89.96 mm (3.5417 in)ProCarManuals.com

Piston Rings

Ring-to-Groove Clearances

After installing a new set of rings, measure ring-to-groove

clearances:

Top Ring Clearance

M/T:

Standard (New): 0.035 - 0.065 mm

(0.0014-0.0026 in)

Service Limit: 0.13 mm (0.005 in)

A/T:

Standard (New): 0.030 - 0.055 mm

(0.0012 - 0.0022 in)

Service Limit: 0.13 mm (0.005 in)

Second Ring Clearance

M/T:

Standard (New): 0.030 - 0.060 mm

(0.0012-0.0024 in)

Service Limit: 0.13 mm (0.005 in)

A/T:

Standard (New): 0.030 - 0.055 mm

(0.0012-0.0022 in)

Service Limit: 0.13 mm (0.005 in)ProCarManuals.com

Engine Control Module (ECM) Reset Procedure

Either of the following actions, will reset the ECM.

Using the OBD II scan tool or Honda PGM Tester to clear the ECM's memory.

NOTE: See the OBD II scan tool or Honda PGM Tester user's manuals for specific operating instructions.

Turn the ignition switch OFF. Remove the CLOCK (7.5 A) fuse from the under-hood fuse/relay box for 10 seconds.

UNDER-HOOD

FUSE/RELAY BOX
CLOCK

(7.5 A) FUSE

III. Final Procedure (this procedure must be done after any troubleshooting)

1. Remove the SCS Service Connector if it is connected. If the SCS service connector is connected and there are no

DTCs stored in the ECM, the MIL will stay on when the ignition switch is turned on.

2. Do the ECM Reset Procedure.

3. Turn the ignition switch OFF.

4. Disconnect the OBD II scan tool or Honda PGM Tester from the Data Link Connector (16P).

IV. Known-Good ECM Substitution

The ECM is part of the immobilizer system. If you substitute a known-good ECM, the ECM will have a different immo-

bilizer code. In order for the engine to start, you must rewrite the immobilizer code with the Honda PGM Tester.

(cont'd)ProCarManuals.com

PGM-FI System

System Description (cont'd)

3. Fuel Cut-off Control

During deceleration with the throttle valve closed, current to the fuel injectors is cut off to improve fuel economy at

speeds over 1,500 rpm.

Fuel cut-off action also takes place when engine speed exceeds 8,300 rpm, regardless of the position of the throttle

valve, to protect the engine from over-revving.

4. A/C Compressor Clutch Relay

When the ECM receives a demand for cooling from the air conditioning system, it delays the compressor from being

energized, and enriches the mixture to assure smooth translation to the A/C mode.

5. Evaporative Emission (EVAP) Purge Control Solenoid Valve

When the engine coolant temperature is below 153°F (67°C), the ECM controls the EVAP purge control solenoid valve

which cuts vacuum to the EVAP purge control canister diaphragm.

6. Intake Air Bypass (IAB) Control Solenoid Valve

When the engine speed is below 4,800 rpm, the IAB control solenoid valve is activated by a signal from the ECM. Intake

air then flows through the smaller chamber, and high torque is delivered. To increase air flow at engine speeds higher

than 4,800 rpm, the solenoid valve is deactivated by the ECM, and the intake air flows through the larger chamber.

7. Exhaust Gas Recirculation (EGR) Control Solenoid Valve

When the EGR is required for control of oxides of nitrogen (NOx) emissions, the ECM supplies ground to the EGR

control solenoid valve which supplies regulated vacuum to the EGR valve.

ECM Fail-safe/Back-up Functions

1. Fail-Safe Function

When an abnormality occurs in a signal from a sensor, the ECM ignores that signal and assumes a pre-programmed

valve for that sensor that allows the engine to continue to run.

2. Back-up Function

When an abnormality occurs in the ECM itself, the fuel injectors are controlled by a back-up circuit independent of the

system in order to permit minimal driving.

3. Self-diagnosis Function [Malfunction Indicator Lamp (MIL)]

When an abnormality occurs in a signal from a sensor, the ECM lights the MIL and stores the diagnostic trouble code

in erasable memory. When the ignition is initially turned on, the ECM supplies ground for the MIL for two seconds to

check the MIL bulb condition.

4. Two Trip Detection Method

To prevent false indications, the Two Trip Detection Method is used for the H02S, fuel metering-related, idle control

system, ECT sensor, EGR system self-diagnostic functions and EVAP control system. When an abnormality occurs,

the ECM stores it in its memory. When the same abnormality recurs after the ignition switch is turned OFF and ON (II)

again, the ECM informs the driver by lighting the MIL.

However, to ease troubleshooting, this function is cancelled when you short the service check connector. The MIL will

then blink immediately when an abnormality occurs.

5. Two (or three) Driving Cycle Detection Method

A "Driving Cycle" consists of starting the engine, beginning closed loop operation, and stopping the engine. If misfir-

ing that increases emissions or EVAP control system malfunction is detected during two consecutive driving cycles,

or TWC deterioration is detected during three consecutive driving cycles, the ECM turns the MIL on.

However,
to
ease
troubleshooting,
this
function
is
cancelled when
you
short
the
service check connector.
The MIL
will

then blink immediately when an abnormality occurs.ProCarManuals.com

Clutch Disc

Inspection

1. Inspect the lining of the clutch disc for signs of slip-

page or oil. Replace it if it is burned black or oil

soaked.

2. Measure the clutch disc thickness.
3. Measure the depth from the lining surface to the

rivets, on both sides.

If the thickness is less than the service limit,

replace the clutch disc.
If the depth is less than the service limit, replace

the clutch disc.ProCarManuals.com

Reverse Shift Arm, Reverse Shift Fork

Clearance Inspection

1. Measure the clearance between the reverse shift

arm and the reverse shift piece.

2. If the clearance exceeds the service limit, measure

the width of the groove in the reverse shift arm.

If the width of the groove exceeds the standard,

replace the reverse shift arm with a new one.

If the width of the groove is within the standard,

replace the reverse shift piece with a new one.
If the width is less than the standard, replace the

reverse shift arm with a new one.

If the width is within the standard, replace the

reverse shift fork with a new one.
3. Measure the clearance between the reverse shift

arm and reverse shift fork.

4. If the
clearance exceeds
the
service
limit,
measure

the width of the reverse shift arm.ProCarManuals.com