Precision Wired Up with Cambiare 5-Wire Lambda Sensors
Vehicle manufacturers have been fitting lambda sensors to cars since the late 1970’s. The sensors provide valuable information to the ECU that help the vehicle’s engine run as efficiently as possible whilst producing as few emissions as possible.
BACK TO BASICS
In order for a vehicle’s engine to run at optimal performance, a specific mixture of air and fuel is essential. The ‘perfect’ ratio for this mixture is known as stoichiometric air/fuel ratio which in petrol engines consist of 14.7 parts of air for every 1 part of fuel (14.7:1). This means that when ignited, the volume of air present in the mixture is the ‘perfect’ amount to completely burn all of the available fuel within the combustion chamber.
This perfect air-to-fuel ratio is difficult to achieve within a vehicle’s engine. Lambda sensors are therefore used to monitor oxygen levels that pass through the exhaust following combustion. The residual air indicates whether the air-to-fuel ratio is too rich (too much fuel) or too lean (too much air).
Lean mixtures improve a vehicle’s fuel economy. However, it can reduce power and cause an increase in oxides of nitrogen (NOx) whereas rich mixtures can increase power but cause higher carbon monoxide (CO) emissions.
The Lambda sensor produces a voltage signal based on the volume of air detected in the exhaust. If the mixture is too rich, the sensor produces a voltage of around 0.9 volts. When the mixture is too lean, it produces around 0.1 volts, and the perfect stoichiometric air/fuel ratio produces 0.45 volts. To compensate for imperfect mixture ratios, the ECU adjusts the fuel mixture by adding more fuel when the mixture is lean, or using less fuel when it is rich.
Although there have been advances over the years to improve various aspects of the sensor, this basic signal technology has been used for decades.
THE NEWEST GENERATION OF LAMBDA SENSORS
Since 2005 with the introduction of the Euro 4 emissions standards in which the acceptable levels of pollutants emitted from a vehicle were lowered, the 5-wire Lambda Sensor (aka wideband sensor) has become an essential component in modern, lean burn and direct injection engines. This is due to the operating limitations of the original Lambda sensors technology, in that it’s unable to indicate to the ECU how rich or lean the air to fuel mix is.
5-wire Lambda Sensors send a more precise indication to the ECU of the exact air-to-fuelfuel ratio. The signal emitted is a live, continuous current measured in milliamps and converted into a voltage by the engine’s ECU. This helps the engine to adjust fuel injection according to the measurements, deliver greater accuracy and achieve stricter emission targets than other types of sensors.
The 5 wire functions
1st wire = signal voltage
2nd wire = isolates the ground of the signal to reduce signal noise
3rd and 4th wires = heating element so the sensor starts operating faster and more reliably
5th wire = detects by how much the air-fuel ratio is too rich or lean
Vehicle electronics specialist Cambiare has recently introduced twenty- five 5-wire lambda sensors to range, covering more than 700,000 vehicles on the UK roads.
• VE381747 for Suzuki Swift 1.2 (10/2010>)
• VE381745 for Renault Megane 1.6 (11/2008-08/2015)
• VE381751 for VW Golf 1.4 (11/2012>)
All new-to-range parts are OE quality, backed by 2 year/30,000 mile warranty. Find out more from the Cambiare website (www.cambiare-ve.com).