PAT


suppliers


aaaa logo

Member of Australian Automotive Aftermarket Association

PRTC Council Member

4WD Council Member



Latest News

Variable Camshaft Actuators (VCA) Oil control Valves

What a Technician needs to know when working on or diagnosing faults on a Variable Valve Timing (VVT) system.

Brief description of VVT system.

The variable valve timing system is now commonly fitted by most vehicle manufacturers to advance and retard the camshaft in relation to the crankshaft position within the cylinder.

Early VVT systems were utilised to increase engine performance.
Later (more advanced) Cam – Changing and Cam – Phasing VVT systems are utilised to increase Torque, Power, Efficiency and Idle performance throughout the total RPM range.

A typical advanced system is the Toyota VVTL-i with continuous cam-phasing VVT and 2 stage variable valve lift plus valve opening duration applied to both intake and exhaust valves.

A typical simple VVT valve cycle.

The BMW (VVT) Vanos system (Variable Nockenwellen Steuerung) at lower engine speeds, opens the valves later during the intake stroke. This increases the vacuum and scavenging effect which improves idle quality and acceleration from a stationary condition. As the engine RPM increases, the valves are opened earlier to enhance Torque.



In the E46 3-series, the Double-Vanos shifts the intake and exhaust camshaft within a range of 40° and 25° respectively.

How does the VVT actuator oil control valve affect the VVT system?

The VVT system generally utilises oil pressure as the internal force for the actuator to change the Camshaft phasing. The flow control of the oil pressure is performed by the VVT actuator control valve that is operated by a pulse width modulated signal from the PCM. The control valve integrates a solenoid and spool valve that allows engine oil to be directed to various paths.

 

A typical VVT hydraulic circuit schematic.


Typical VVT faults and causes that affect its operation.

Being a mechanical/hydraulic system that is controlled by electronics, there are a few areas of concern if the system is not maintained correctly.

  • When the engine oil is contaminated due to extended service intervals or incorrect engine oil viscosity used during an oil service, the VVT system may create a sluggish or seized VVT actuator that can result in poor engine performance and even a no start condition.
  • Excess contamination may generally cause the spool valve in the VVT actuator control valve to jam and create an excessive advanced or retarded camshaft condition.
  • Failed electrical circuits will cause the actuator to remain in the retarded or advanced position that would depend on the spool valve position in the VVT oil control valve.
  • VVT Actuator internal gears and seals may wear over time and cause incorrect VVT operation.
  • Low engine oil pressure that can cause incorrect VVT operation and misdiagnosis.
  • Incorrect valve timing due to wear in the drive chain/belt or after drive chain /belt replacement.

Note:  It is important to investigate any Service Information Bulletins that relate to the VVT system when a malfunction in the system occurs. A malfunction in the VVT system may cause the “Service Engine Soon” (MIL) light to illuminate and multiple fault codes logged in conjunction with loss of engine power and possible rattling sounds.

Oil service schedules need to be adhered to as delaying service intervals is a main factor for VVT failure due to oil contamination and mechanical wear.

Testing the Oil Control Valve.

If the oil control valve is suspected of being faulty, checking the electrical resistance of the coil windings is a simple task.
           
Typical resistance readings for KIA vehicle VVT valves at 20 Deg C are:

  • Denso - 6.9 to 7.9 Ohms
  • Delphi - 6.7 to 7.7 Ohms
  • Siemens - 6.8 to 8.0 Ohms

If the resistance is within specs, the movement of the spool valve may be inhibited by internal foreign objects. Movement of the spool valve may be checked by powering the 2 terminals of the unit and it is recommended to renew the valve if it is suspect.

On car testing of the VVT.
           
Utilising a suitable scanner and a suitable oscilloscope. Checking Camshaft and Crankshaft position sensor signals as well as PWM signals can assist the Technician with VVT operational diagnosis.

Typical VVT vehicle system identification.

VVT Chrysler, GM, Proton, Suzuki, Isuzu, VAG group, Toyota
VVTi  Toyota, Lexus
AVCS Subaru
AVLS Subaru
CPS Proton
CVVT Hyundai, KIA
DCVCP General Motors
DVVT  Daihatsu
MIVEC Mitsubishi
MultiAir  Fiat
N-VCT  Nissan
S-VT  Mazda
Ti-VCT Ford
VANOS  BMW
ValveTronic BMW (also adjusts valve lift)
VarioCam Porsche
VTEC Honda
i-VTEC  Honda
VTi   Citroen
VVC   MG, Rover
ValveLift Audi
VVEL Nissan, Infinity
CamTronics  Mercedes

The Premier Auto Trade Emission range includes more than 45 Variable Camshaft Actuators (VCA), covering over 4.1 million vehicle applications in Australia and NZ.

When you supply and fit products from Premier Auto Trade you can expect a product designed and tested to the vehicle manufacturer’s specifications offering OE form, fit and function. Premier Auto Trade distributes products throughout Australia via a network of specialised resellers and leading automotive groups.

 



Latest News

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