RPM 's Bounce

[Neighbor]

Performed the turbo actuator test, air pressure was built up to 120 psi, what happens every 2 or three times during the extended phase. Air leaks out the bottom of the diaphram for about 3 seconds then stops, but the arm stays extended. Did that test about 10 x same response every time. Is that normal? Also found code 0241 erratic speed sensor. Removed sensor and cleaned and knocked off some rust around tone ring.