2003 Audi A6 • V8 AWD Automatic • 95,600 miles

The engine light came on my 2003 Audi A6 4.2 litre V-8 Quattro. Diagnostic test indicates insufficient air flow change while air pump switching test. Probable causes: secondary air vacuum hose off or leaking, secondary air hose off or damaged, failed air pump bypass solenoid, failed diverter valve system. My question: Can any of these conditions cause excessively loud engine roar during acceleration and a loud engine idle?
January 31, 2011.

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