Variable nozzle turbos were first launched in the industry by Garrett in the mid 90’s and are now found on most diesel engines. It was the introduction of variable nozzle (also known as variable geometry) technology in turbos at the same time as common rail fuel injection systems, which led to the huge increase in popularity of small displacement diesel engines in passenger cars.
As the decades moved on, emission levels have continued to reduce as vehicles have been designed to meet the Euro 4, 5 then 6 regulations. As a result of these changes, engine technology and turbo technology increased in complexity, and the settings and control of the variable nozzles in the turbocharger have become more critical to the correct operation of the turbo. This is now presenting new challenges to turbo repairers as the correct setting of the turbo on later models now requires further specialist equipment in the form of an air flow rig.