Pressure Check

Ensure all intake air hoses are connected. Place pressure hose and "T" fitting in actuator hose leading to intake manifold. See Fig 1. Start engine.
On manual transmission equipped models, accelerate vehicle with throttle valve fully open. Measure pressure when engine RPM is greater than 2500 RPM. See TURBOCHARGER PRESSURE table.
On automatic transmission equipped models, drive vehicle from standing start with transmission in L with throttle valve fully open. Measure pressure with engine speed greater than 3500 RPM. See TURBOCHARGER PRESSURE table.
If pressure is less than specification, check intake air and exhaust systems for leaks. If there are no leaks, replace turbocharger. If pressure is greater than specification, check actuator hose for leaks or cracks. If no leaks or cracks are present, replace turbocharger.

Fig 1: Checking Turbo Pressure (Celica Shown; Supra Is Similar)

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NOTE: To check turbocharger pressure sensor and vacuum switching valve, see ENGINE SENSORS & SWITCHES in this article.

TURBOCHARGER PRESSURE

Application	psi (kg/cm² )
Automatic Transmission	4.8-6.0 (.33-.44)
Manual Transmission	5.5-7.5 (.40-.55)