PAT


suppliers


aaaa logo

Member of Australian Automotive Aftermarket Association

PRTC Council Member

4WD Council Member



Latest News

Idle Speed Control

Although all new petrol engine vehicles currently manufactured utilise the Electronic Throttle Body control system for both acceleration control and Idle stability, there are millions of vehicles still driving the streets that are fitted with a separate Idle control system that still requires servicing, testing and renewing and the occasional resetting.

We are looking at the characteristics of two of the most common systems used, which are the ECU operated Idle Air Control (IAC) control system and the Stepper Motor Idle speed control.

IAC – Idle Air Control.
This was a widely used system in the industry (generally local and Japanese vehicles) and because of its location on the throttle body can be problematic due to carbon build-up creating insufficient or excess idle speed.

All IAC systems retain common characteristics which include:

  • It has a “spring return” for the internal air control valve that retains to the base idle position when electrically disconnected or when not activated.
  • It is generally duty cycle pulsed by the ECU to move the internal control valve.
  • Some units may or may not have internal electronic circuitry, which make replacing with the correct unit important.
  • Some may, or may not, be adjustable.

Common Faults on this type of IAC.

  • Sticking internal valve creates high or low idle speeds (cleaning not always successful)
    Note: High Idle speed may cause hunting at idle only.
  • Moisture in the electrical connector may damage the electronics (if electronics fitted)
  • Dismantling this system to clean may make it difficult to calibrate. (do not dismantle)
  • Ensure correct test procedure for the unit being tested.

Stepper Motor Idle Control.
This was a commonly used system found in vehicles from all corners of the world.
Typically, the V6 and V8 GM vehicles utilised a simple stepper motor system that is operated by the ECU in small steps to open and restrict the idle bypass passage at the throttle body.

Note: Disconnecting the harness from this stepper type control valve, would lock the pintle in the position it was
Disconnected - until it is reconnected. It “does not” revert to a base position as the IAC valve does.

A fully extended pintle creating a fully closed passage (Base idle position) would have a diagnostic scanner reading of Zero steps. Contracting the pintle to a fully open position would then indicate approx. 255 steps on the scanner.
Neither of these positions are suitable for idle. The ECU will generally move the pintle to a position where there is sufficient air intake for a stable idle. A typical “hot idle step reading” displayed by a scanner on a system without major vacuum leaks or carbon build up would indicate near 25 steps. Any major variation would require close attention to these areas.

The desired Stepper Motor Position for idle is based on:

  • Coolant temperature
  • Actual RPM
  • Engine load
  • Battery volts

Common faults on this type of Idle control system.

  • Stepper motor windings open/short circuit.
  • Like the IAC motor, carbon build up can be problematic.
  • Incorrect unit fitted as a replacement. (pintles vary in sizes to suit different throttle bodies)
  • It is important to fit the correct unit as many smaller pintle units may fully unwind from the motor.

Many of the Stepper motors are integrated in a housing with a coolant temperature activated Auxiliary air control valve. This can be problematic with age, as the alloy housings corrode and coolant under pressure enters the stepper motor windings. A short circuit windings condition occurs and may damage the stepper motor circuit in the ECU. It is important to be aware of these precautions. Generally, a reset procedure is required on many of these combined stepper motor and auxiliary valve assemblies.



Latest News

Tech Tips - Wheel Speed Sensors (WSS)

Positive Crankcase Ventilation (PCV) and Oil Separators

Common Rail Diesel Pumps (HDP)

Exhaust Gas Temperature Sensor (EGT)

Hose Clamps

MAP Sensors (Manifold Absolute Pressure)

Electric Water Pumps

Pulse Width Modulation (PWM)

Mass Air Flow Sensors (Hot Wire/Film)

Petrol Fuel Injector Replacement

Electronic Throttle Bodies (TBO)

Dual Petrol Injection Systems – Technical Tip

Wheel Speed Sensors – More than just ABS

PAT Expands Emission Sensor Range

PAT Racing & Performance Injector Range Upgrade

Coils ain’t Coils!

ICON SERIES Range Grows

Oil Level and Oil Temperature Sensors Operation

Failed Air Temperature Sensors Symptoms

MAP Sensors Testing

TI Automotive Mustang Performance Pump

New ICON SERIES Hose Clamp Range

New Premium Sensors Ranges

Relay problems on vehicle

Test Equipment and Tools

Fuel Rail Sensors (FRS)

Failing Secondary Ignition

Testing Electric Fuel Pumps

Performance Fuel Rails and Filters

Testing CAM Angle Sensors (CAM)

Testing Electric Valve Solenoids (EVS)

Electronic Throttle Bodies

Performance Fuel Cells & Surge Tanks

Fault Finding Fuel Pressure Regulators (FPR)

Testing Variable Camshaft Actuators (VCA)

Testing Accelerator Pedal Position Sensors (APS)

Diagnosing Crank Angle Sensors (CAS)

Performance Regulators and Gauges

Differentiating Wheel Speed Sensors (WSS)

Mass Air Flow Sensors - Hot Film

Mechanical Fuel Pumps (MFP)

ICON Series Hoses

Particulate Matter Sensors (PMS)

Performance Fuel Injectors

Fuel Injectors (GDI)

DENSO Spark Plugs

Performance Fuel Pumps

Cooling Fan Switches (CFS)

Water Temperature Sensors (WTS)

Reverse Light Switches

Oil Temperature Sensors (OTS)

BMC Air Filters

Flasher Cans

Exhaust Pressure Sensors (EPS)

Power Steering Switches

Coolant Temperature Sensors (CTS)

Variable Intake Manifolds (VIM) and Intake Control Valves (ICV)

Oil Level Sensors (OLS)

Throttle Position Sensors (TPS)

Air Temperature Sensors (ATS)

Ignition – Condensers, Contact Sets, Distributor Caps and Rotors

Fuel System Accessories (FSA)

MAP Sensors (MAP)

Relays (REL)

HALL Sensors and Pickups (HAL)

Fuel Rail Sensors (FRS)

Speed Sensors (SPS)

New ICON Series Fuel Pump Range

New ICON Series Hose Range

Performance Range Increase Continues

PAT Oxygen Sensor Range Expands

PAT Expands Automotive Aftermarket Presence

Equipment and Tools

Electric Fuel Pumps (EFP)

Electric Valve Solenoids (EVS)

CAM Angle Sensors (CAM)

Ignition Modules (MOD)

Injector Service Components

Exhaust Gas Temperature Sensors (EGT)

Throttle Bodies

Knock Sensors

Ignition Coils

Fuel Injectors (Petrol)

Variable Camshaft Actuators (VCA) Oil control Valves

Accelerator Pedal Position Sensors (APPS)

Exhaust Gas Recirculation Valves (EGR)

Relocation of Sydney Distribution Centre

Wheel Speed Sensors (WSS)

High Tension - Ignition Lead Sets (ILS)

Suction Control Valves (SCV)

Mass Air Flow (MAF) Sensors

Crank Angle Sensors (CAS)

Fuel Pressure Regulators (FPR)

Oil Pressure Sensors

Exhaust Gas Oxygen Sensors

Shedding Light on Stop Light Switches

Ignition Distributors

Common Rail Diesel (CRD) Fuel Injectors

Idle Speed Control

New Distribution Centre Opening in ADELAIDE

New Distribution Centres Opening in PERTH and DARWIN

New Fuel Catalogue from Premier Auto Trade

BMC 4WD Air Filters Range Expands

New MVP Fuel Injector Range

PAT Developing Programs on Demand

New Premium Packaging for PAT

New Product Ranges Released By PAT

PlusQuip Test Equipment Range Expands

New Raceworks Catalogue

New Exhaust Gas Temperature Sensors

New Trade Catalogues from Premier Auto Trade

New Distribution Centre Opening in Adelaide

More European Parts from Premier Auto Trade

New PlusQuip Fuse Current Tester

PAT Pumped up!

Coils ain't Coils!

New PlusQuip Electronic EGR, Throttle Body, and Actuator Tester

New breed of High Performance products!

New Ignition Coil and Lead Set Kits

Wheel Speed Sensor Program Launched

Premier Ignition Lead Program Launch

Ignition Coils - Coils ain't Coils!

PlusQuip Battery Testers Launch

Premier Auto Trade Supporting Local Racing

Oval Trumpet Airbox (OTA) for 4WD applications from BMC Air Filters

BMC Air Filters NOW AVAILABLE from Premier Auto Trade

Premier Ignition Coils

MAP-013 and KNS-021 Now Back in Stock

BMC Air Filter partners with Premier Auto Trade

Premier Auto Trade opens South Australian Distribution Centre

Direct Fit Oxygen Sensor Range Hits 700

Automotive Electro-Mechanical Relays Types / Faults / Diagnosis

PlusQuip Tools and Equipment Launch

PlusQuip Fuel Line Repair Kit

PlusQuip Fuel Injector Service Kit

E85 High Performance with Premier Auto Trade

Testing EGR Systems (Pt 2)

New Delphi Fuel Module and Ignition Coil Range

Fuel Injector Service Components from Premier Auto Trade

Older News...

   privacy statement   terms of use   terms and conditions   sitemap   news  

© PremierAutoTrade