To boost, or not to boost...

Back in the January issue (issue 305), I explained a fault that had occurred with our Ducato-based motorhome.

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A brief summary is that when using the 'Resume' feature of the cruise control, a turbo boost pressure fault combined with a boost control 'out of range' fault happened and restricted the power of the engine. Driving normally avoided it happening, but when using Resume on the cruise control the system takes it all the way to 100% throttle to accelerate to the last set speed.

The boost control is done by variable vanes in the exhaust side of the turbo that adjust how much of the exhaust gases impinge on the impeller. If they don't open far enough the turbo can 'overboost', which is not good for the engine so it throws a fault code and restricts power.