Boost Pressure

WARNING: This page is about a different car, the 1989 Mazda RX-7. However, it is still accessible from the selected car via links, so may be relevant.

Disconnect air hose between intercooler and solenoid valve. Connect pressure gauge. See Fig 1 . Plug duty solenoid side of hose. Warm engine to normal operating temperature.
Measure boost pressure while suddenly increasing engine speed. At approximately 4000 RPM boost should begin. Above approximately 5000 RPM pressure should be more than .07 psi (0.049 kg/cm² ). If boost pressure is not within specification, proceed to following tests as necessary.

Fig 1: Testing Boost Pressure

Courtesy of MAZDA MOTORS CORP.