1987 Saab 9000 Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Engine Performance: System: Turbocharger: Operation: Notes

As engine operation begins, exhaust gases flow through the turbocharger's turbine impeller, causing it to rotate. Gases are expelled through the turbine to the exhaust pipe. As the turbine spins, its shaft turns the compressor impeller, compressing the intake air.

At idle speeds the air compression has little effect upon its operation. However, as engine speed is increased (partial load), the pressurized air enters the system faster, and exhaust gases are expelled faster. The more exhaust gases passing over the turbine impeller, the faster it turns, and the more pressurized air is delivered to the engine.

At full load, the throttle valve is fully open and charge pressure increases. At 8.7-10.1 psi (.61-.71 kg/cm2 ), the valve in the charge pressure regulator opens, permitting exhaust gases to flow directly to the exhaust pipe, bypassing the turbine impeller.

In the event the valve sticks open, charge pressure increases to 13.1-14.5 psi (.92-1.02 kg/cm2 ). This causes a pressure switch to break current flow to the fuel pump, thereby preventing engine damage. Pressure switch is located on the turn signal flasher bracket under the instrument panel.

Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

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