In Detail: The 2.8L Duramax diesel’s VGT Turbo
The new 2.8L Duramax turbo-diesel is available in 2016 Colorado and Canyon LT and Z71 Crew Cab models. It generates 181 horsepower and 369 lb.-ft. of torque, has a compression ratio of 16.5:1, along with a common rail direct injection fuel system, dual overhead camshafts and a variable geometry turbocharger (VGT).

The turbocharger is water cooled and bolted to the exhaust manifold of the engine. Its body assembly contains a contactless inductive VGT position sensing element that is managed by a customized integrated circuit. The VGT position sensor is mounted within the VGT body assembly and is not serviceable. The turbocharger vanes are normally open when the engine is not under a load.

The ECM will close the turbocharger vanes to increase engine power and to create a high pressure, using a boost pressure actuator. The ECM will often close the turbocharger vanes to create back pressure to drive exhaust gas through the exhaust gas recirculation (EGR) valve as required. At extreme cold temperatures, the ECM may close the turbocharger vanes at low load conditions in order to accelerate engine coolant heating. The ECM may also close the turbocharger vanes under exhaust braking conditions.