Acura NSX 1990-2005 Emissions & Sensor Bolt Torque Specifications
Acura NSX 1990-2005

Acura NSX 1990-2005 Emissions & Sensor Bolt Torque Specifications

This page provides detailed torque specifications for all emissions sensors on the 1990-2005 Acura NSX, including oxygen sensors, EGR valve, and other related components.

Updated

Important Information

Safety guidelines and reference information for proper torque application

Quick Reference Guide
ft-lbs → Nm
× 1.356
ft-lbs → kg-m
× 0.138
Nm → ft-lbs
× 0.738
in-lbs → ft-lbs
× 0.083

Common Torque Patterns

Star Pattern

Used for wheels and other circular bolt patterns

Star Pattern torque pattern diagram showing proper bolt tightening sequence
Cross Pattern

Used for gaskets and cover plates

Cross Pattern torque pattern diagram showing proper bolt tightening sequence
Sequential Pattern

Used for head bolts and other critical components

Sequential Pattern torque pattern diagram showing proper bolt tightening sequence

Common Mistakes to Avoid

Over-tightening

Exceeding the specified torque value can stretch or break fasteners, damage threads, or crack components.

Prevention:

Always use a calibrated torque wrench and follow specifications exactly.

Incorrect Torque Sequence

Tightening bolts in the wrong order can cause uneven pressure distribution and potential leaks or damage.

Prevention:

Follow the manufacturer's specified torque sequence pattern.

Dirty Threads

Dirt, rust, or old thread locker can affect torque readings and proper fastener tension.

Prevention:

Clean and inspect all threads before assembly. Use new thread locker if specified.

Reusing TTY Bolts

Torque-to-yield bolts are designed to stretch and must not be reused.

Prevention:

Always replace TTY bolts with new ones. They are single-use only.

Dry vs. Lubricated

Not accounting for whether torque specs are for dry or lubricated fasteners can lead to incorrect tension.

Prevention:

Check if specs are for dry or lubricated threads. Use specified lubricant when required.

Recommended Tools

Torque Wrench (1/4" Drive)

Range: 2-25 ft-lbs
Small fasteners, delicate components

Torque Wrench (3/8" Drive)

Range: 10-100 ft-lbs
Most common automotive fasteners

Torque Wrench (1/2" Drive)

Range: 30-250 ft-lbs
Large fasteners, wheels

Angle Gauge

Torque-to-yield (TTY) bolts

Torque Wrench Care

  • Calibrate annually or after 5,000 clicks
  • Store at lowest setting
  • Keep clean and lubricated

Search Specifications

Search by component name, bolt size, or description

Torque Calculator

Convert between different torque units

3.0l-engine Cylinder Head

Torque specifications for the cylinder head and related components.

1

Exhaust Manifold/Header Bolts

M8 x 1.25
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Torque bolts in a star pattern to ensure even clamping pressure. Apply anti-seize compound to threads.

3.0l-engine Block

Torque specifications for engine block components.

1

Crankshaft Position Sensor Bolt

M6 x 1.0
Torque Value
8 ft-lbs (11 N·m)
Important Notes
Ensure sensor is properly seated before tightening. Do not overtighten.
2

Camshaft Position Sensor Bolt

M6 x 1.0
Torque Value
8 ft-lbs (11 N·m)
Important Notes
Ensure sensor is properly seated before tightening. Do not overtighten.
3

Knock Sensor Bolt

M8 x 1.25
Torque Value
15 ft-lbs (20 N·m)
Important Notes
Ensure sensor is properly seated before tightening. Do not overtighten.

Intake Manifold

Torque specifications for the intake manifold and associated sensors.

1

Intake Manifold Bolts

M8 x 1.25
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Torque bolts in a criss-cross pattern to ensure even clamping force. Ensure proper gasket is in place.
2

MAP (Manifold Absolute Pressure) Sensor Mounting Bolt

M5 x 0.8
Torque Value
8 ft-lbs (11 N·m)
Important Notes
Do not overtighten, as this could damage the sensor. Estimated value.
3

IAT (Intake Air Temperature) Sensor Mounting Screw/Bolt

M4 x 0.7
Torque Value
5 ft-lbs (7 N·m)
Important Notes
Do not overtighten. Estimated value.

Exhaust System

Torque specifications for the exhaust system and associated sensors.

1

Exhaust Pipe to Exhaust Manifold/Headers Bolts

M8 x 1.25
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Apply anti-seize compound to threads.
2

Catalytic Converter to Exhaust Pipe Bolts

M8 x 1.25
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Apply anti-seize compound to threads.
3

Oxygen (O2) Sensor

M18 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
Apply anti-seize compound to threads to prevent seizing.

Fuel System

Torque specifications for fuel system components.

1

Fuel Rail Bolts

M6 x 1.0
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Ensure fuel rail is properly seated on the intake manifold.
2

Fuel Injector Bolts

M6 x 1.0
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Ensure fuel injector O-rings are properly seated to prevent leaks.

Throttle Body

Torque specifications for the throttle body and associated sensors.

1

Throttle Body Bolts

M8 x 1.25
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Ensure throttle body gasket is properly seated to prevent vacuum leaks. Torque in a criss-cross pattern.
2

Throttle Position Sensor (TPS) Screws

M4 x 0.7
Torque Value
2 ft-lbs (3 N·m)
Important Notes
Do not overtighten, as this could damage the sensor. Estimated value.

Egr System

Torque specifications for EGR system components

1

EGR Valve Bolts

M8 x 1.25
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Ensure EGR valve gasket is properly seated to prevent leaks.

Troubleshooting Guide

Common issues, diagnostic steps, and prevention guidelines

Common Issues

Bolt stretching, stripped threads, uneven torque patterns

Loose Components

Symptoms:
  • Rattling or vibration noises
  • Visible movement in components
  • Uneven panel gaps
Solutions:
  • Clean threads and mounting surfaces
  • Replace damaged fasteners
  • Apply proper torque in sequence
  • Use thread locker if specified

Stripped Fasteners

Symptoms:
  • Unable to achieve proper torque
  • Fastener spins freely
  • Visible thread damage
Solutions:
  • Use thread repair kit if appropriate
  • Install thread insert (HeliCoil)
  • Replace component if threaded hole is damaged
  • Upgrade to higher grade fastener if recommended

Overtightened Components

Symptoms:
  • Cracked or deformed parts
  • Broken fasteners
  • Compressed gaskets or seals
Solutions:
  • Replace damaged components
  • Use new fasteners
  • Follow proper torque sequence
  • Verify correct torque specifications

Diagnostic Steps

Visual inspection, torque verification, thread assessment

1

Visual Inspection

Inspect the affected area for any visible signs of damage or wear

  • Check for cracks or deformation
  • Look for signs of excessive wear
  • Verify proper fastener installation
2

Torque Verification

Verify the torque applied to the fasteners

  • Check the torque wrench calibration
  • Verify the torque specification
  • Compare the applied torque to the specification
3

Thread Assessment

Assess the condition of the threads

  • Check for signs of thread damage
  • Verify the thread type and size
  • Check for proper thread engagement

Prevention Guidelines

Best practices, maintenance tips, tool care

Best Practices

  • Always follow the recommended torque specification
  • Use the correct type and size of fasteners
  • Verify the torque wrench calibration regularly

Maintenance Tips

  • Regularly inspect the affected area for signs of wear or damage
  • Replace damaged or worn-out components promptly
  • Keep the work area clean and organized

Tool Care

  • Regularly clean and maintain the torque wrench
  • Store the torque wrench in a dry and secure location
  • Verify the torque wrench calibration before each use

Frequently Asked Questions

Find answers to common questions about torque specifications

Q1

Why is it important to use the correct torque specifications for emissions sensors?

Using the correct torque specification ensures proper sealing and prevents damage to the sensor, exhaust components, and threaded mounting points. Over-tightening can strip threads or crack the sensor housing, while under-tightening can lead to exhaust leaks, false readings, and potential sensor failure. These issues can trigger the 'Check Engine' light and impact emissions performance.

Q2

What happens if I over-torque an emissions sensor bolt?

Over-torquing an emissions sensor bolt can lead to several problems. The most immediate is damage to the sensor itself, potentially cracking the housing or damaging internal components. You may also strip the threads in the exhaust manifold or bung, requiring costly repairs. Additionally, an over-torqued sensor may not seal correctly, leading to exhaust leaks.

Q3

What is the best way to tighten these bolts to the correct torque?

The best method is to use a calibrated torque wrench. Apply a steady, even pressure to reach the specified torque value. Avoid using excessive force or relying on a 'feel' method, especially with delicate sensors. Always double-check the torque setting on the wrench before tightening and verify its accuracy periodically.

Q4

Do I need to use any special type of thread lubricant or anti-seize on emissions sensor bolts?

It is generally recommended to apply a small amount of high-temperature anti-seize compound to the threads of emissions sensor bolts before installation, especially if the sensor is in the exhaust stream. This will prevent the bolts from seizing or binding over time due to heat and corrosion. However, avoid getting any anti-seize on the sensor’s electrical connectors.

Q5

If I am replacing an emissions sensor, is there anything else I should be checking?

Yes. When replacing an emissions sensor, it's good practice to inspect the electrical connector for any damage or corrosion. If damaged, the connector may also require replacement, and that can cause inaccurate sensor readings. Also, visually check the mounting location for any damage or leaks before installing the new sensor. Ensure that any wiring harnesses connected to the sensors are clear and undamaged.

Environmental Considerations

Temperature, humidity, and seasonal effects on torque specifications

Temperature Effects

Includes: High Heat, Cold Weather, Thermal Cycling

Temperature can significantly impact torque values and fastener behavior

Cold Weather

Effects:
  • Increased material brittleness
  • Higher torque required due to thread contraction
  • Reduced thread lubricant effectiveness
Recommendations:
  • Allow components to warm to room temperature when possible
  • Consider using winter-grade thread lubricants
  • Check torque values more frequently during winter months

Hot Weather

Effects:
  • Thermal expansion of components
  • Decreased friction in threads
  • Accelerated lubricant breakdown
Recommendations:
  • Check torque when components are at normal operating temperature
  • Use temperature-resistant thread lockers
  • Consider re-torquing after heat cycles

Humidity and Corrosion

Covers: Rust Prevention, Salt Exposure, Moisture Control

Moisture and corrosion can affect fastener integrity and torque values

High Humidity

Effects:
  • Accelerated corrosion formation
  • Reduced friction coefficient
  • Potential thread seizing
Prevention:
  • Use corrosion-resistant fasteners
  • Apply appropriate anti-seize compounds
  • Maintain proper protective coatings

Salt Exposure

Effects:
  • Rapid corrosion development
  • Thread damage
  • Seized fasteners
Prevention:
  • Regular underbody washing
  • Use of sacrificial anodes where appropriate
  • Application of protective coatings

Seasonal Maintenance

Spring, Summer, Fall, and Winter maintenance schedules

Spring

  • Inspect for winter damage
  • Clean and protect exposed fasteners
  • Check torque on critical components

Summer

  • Monitor heat-affected components
  • Check expansion-related loosening
  • Inspect cooling system mounts

Fall

  • Prepare for winter conditions
  • Apply corrosion protection
  • Verify all fasteners are properly torqued

Winter

  • More frequent inspection of critical fasteners
  • Check for salt damage
  • Monitor suspension component torque

Related Resources

Tools, service procedures, and technical bulletins

Recommended Tools

Torque Wrench (1/4" Drive)

A calibrated torque wrench capable of measuring in inch-pounds (in-lbs) or Newton-meters (Nm) for accurate torque application on emissions sensor bolts.

  • Adjustable torque settings
  • Click-type mechanism for audible feedback
  • Reversible ratchet head
Learn more

Socket Set (1/4" Drive)

A set of sockets in various sizes to accommodate different emissions sensor bolt heads. Typically includes 10mm, 12mm, and 13mm sockets.

  • Chrome vanadium steel construction
  • Variety of sizes
  • 6-point design for secure grip
Learn more

Socket Extensions (1/4" Drive)

Socket extensions to access emissions sensor bolts in tight or hard-to-reach locations.

  • Available in different lengths
  • Chrome vanadium steel construction
  • Ball detent for secure socket attachment
Learn more

Universal Joint (1/4" Drive)

A universal joint (or wobble extension) allows the socket to be angled, which is necessary when accessing some emissions sensor bolts.

  • Allows for socket angle
  • Chrome vanadium steel construction
  • Durable hinge mechanism
Learn more
Service Procedures

Emissions Sensor Bolt Torque Procedure

Procedure for correctly torquing emissions sensor bolts on a 1990-2005 Acura NSX. Always consult the service manual for the most accurate information.

  • Locate the specific emissions sensor bolt requiring torque adjustment. Refer to the service manual for sensor locations.
  • Ensure the threads of both the bolt and the receiving hole are clean and free of debris.
  • Position the appropriate socket on the bolt head.
  • Attach the socket to the torque wrench.
  • Set the torque wrench to the specified torque value (refer to your service manual for specific torque values per sensor). Typical torque values are around 10-12 Nm for most NSX emissions sensors.
  • Apply smooth and steady pressure on the torque wrench until it clicks or indicates the preset torque value has been reached.
  • Double check the torque value with another pass at a lower torque setting to confirm the initial torque was accurate, if necessary
View full procedure

Oxygen Sensor Removal and Installation

Procedure for removing and reinstalling oxygen sensors and applying proper torque to the fasteners

  • Disconnect the negative battery terminal.
  • Locate the oxygen sensor that needs to be removed. These can be in the exhaust manifold, downpipe, or catalytic converter section.
  • Disconnect the electrical connector of the oxygen sensor.
  • Use the correct size socket or oxygen sensor removal tool to loosen and remove the sensor.
  • Apply anti-seize compound to the threads of the new sensor.
  • Install the new sensor, tightening it by hand first.
  • Use a torque wrench to torque the oxygen sensor to the specified value (typically 40-50 Nm).
  • Reconnect the electrical connector of the sensor.
  • Reconnect the negative battery terminal.
View full procedure
Technical Service Bulletins

Incorrect Torque of Oxygen Sensor Mounting Flange

1998-05-15

Reports of exhaust leaks were found to stem from mis-torqued oxygen sensor mounting flange on early model NSXs. Incorrect torque settings can damage the flange and lead to leaks.

1990-1997

Resolution: Verify torque on Oxygen sensor mounting flange. Ensure proper torque value is applied, and replace any damaged exhaust flanges. The mounting flange is separate from the sensor itself.

EGR Valve Bolt Corrosion

2002-07-20

Reports of exhaust gas recirculation valve (EGR) bolts seizing due to corrosion. This can lead to difficulty in removal and potentially damage to threads during removal and reinstallation of EGR valves. Over-torquing during install is common.

1990-2005

Resolution: When removing the EGR valve, apply penetrating oil to the bolts before attempting removal. Clean and lubricate the threads before installation and apply the correct torque values. Replacement bolts may be necessary.

About the Author

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Alan Montanye - Automotive Technical Specialist
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Alan Montanye

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