Download 1992 Volvo 740 Turbocharger Service Manual – Turbo Boost Pressure Test 1. Connect pressure gauge Volvo tool #5230 (or equivalent) between line to boost pressure gauge and intake manifold connection. 2. Run gauge into passenger compartment. 3. Start engine and run until it reaches operating temperature. 4. Drive vehicle in 3rd gear (2nd for A/T) at approx 1500 RPM. 5. Press accelerator pedal to the floor (but do not engage kick-down). 6. Apply brakes at approx. 3000 RPM while still holding the accelerator pedal in the full load position. Do not apply brakes for more than five seconds. Read boost pressure on gauge. Reading: 50 ±4 kPa (7.1 ±0.6 psi) If boost pressure is correct, turbo system operates correctly. Disconnect all testing equipment and reinstall hose. If boost pressure is incorrect, adjust wastegate valve (refer to ADJUSTMENT PROCEDURES ) and retest. 7. If valve adjustment does not fix the problem, check the following: a. Wastegate valve b. Turbo charger c. By-pass valve d. Turbo over-boost pressure switch e. Turbo boost system Repair or replace bad component(s) and retest.