When the throttle is closed, while the engine is running at cruise rpm (tip-out), the turbocharger boost pressure raises rapidly. The pressure wave strikes a compressor blades causing a knocking noise. To prevent this the ECM opens the recirculation valve which allows excessive boost pressure to vent back to the air cleaner side of the turbocharger compressor.
Tire rotation
To equalize tread wear, it is recommended
that the tires be rotated
every 12,000 km (7,500 miles) or
sooner if irregular wear develops.
During rotation, check the tires for
correct balance.
...
Preparation Of Tools And Measuring Equipment
Be sure that all necessary tools and measuring equipment are available starting
work. ...