VNT Cleaning / Variable Vane Cleaning
If you are suffering intermittent lack of power then this could possibly be down to a jammed Turbo VNT variable vane nozzle ring assembly.
The Variable vane assembly in a turbo is used to control Turbo shaft speed and the Turbo boost pressure required for the RPM and throttle position of your vehicle. The vanes work by directing the exhaust airflow through the Turbo exhaust wheel to increase Turbocharger shaft speed and then open to allow air to pass around the exhaust wheel in order to either maintain shaft speed or reduce as required.
Due to the efficiency required and the accurate adjustment, the clearances in the variable vane nozzle ring are very small.
When an engine is started cold, the vehicles ECU injects more fuel than that of a warm engine, this in turn in many respects means increased emissions and carbon.. Carbon deposits cling to the internals of the Turbo exhaust housing including the nozzle ring. If cold starts are common like on short trips or if the car is used on stop start journeys like around town, then the Turbo will rarely get hot enough to burn off the carbon deposits. As the carbon continues to build up, the variable vane start to jam on the carbon, locking them in position. Once jammed in position the air fuel ratio will no longer be correct with the most common result being not enough air for the amount of fuel entering the engine, the result? overfuelling and MORE carbon build up!.
If caught early enough a good run on a motorway to get the engine nice and hot can cure the issue, in many cases the engine ECU will continue to go into limp mode.
We can offer a cleaning service for this common problem to overcome this issue.
Simply send your Turbocharger into ourselves where we will strip and assess unit. We will then strip the Variable vane nozzle ring into individual component form and clean and polish before assembling and calibrating before returning unit back to yourself. The cost? £60 plus vat and which includes delivery!