Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSSAAB1990900 SPG, STANDARDREPAIR AND DIAGNOSISENGINE PERFORMANCEENGINE CONTROLS - ADJUSTMENTSIDLE SPEED

1990 Saab 900 SPG, Standard

Idle Speed

1990 Saab 900 SPG, StandardSECTION Idle Speed

NOTE: Idle adjusting procedure requires use of a dwell meter.

Ensure engine is at normal operating temperature. Loosen lock nut on throttle and lower dashpot clear of the throttle lever. Pull back rubber on the Automatic Idle Control (AIC) valve connector and connect dwell meter probes to pins No. 2 and No. 3.
Unplug connector from throttle position sensor. Connect jumper lead between pin No. 2 (Green wire) and pin No. 18 (Black/White wire) to simulate closed throttle position sensor. Loosen retaining screws for Throttle Position Sensor (TPS). Rotate TPS clear of throttle butterfly. Start engine and ensure all accessories are off.
NOTE: DO NOT make idle setting when radiator fan is operating.
On models not equipped with air bleed adjusting screw, loosen throttle stop screw lock nut. Turn adjusting screw counterclockwise until screw does not touch throttle linkage.
On models equipped with air bleed adjusting screw, loosen throttle stop screw lock nut. Adjust throttle butterfly-to-housing clearance to .002" (.05 mm). Loosen air bleed screw lock nut and turn air bleed screw clockwise until fully seated.
On all models, dwell meter reading should now be a minimum of 34 degrees. If reading is not to specification, check for vacuum leaks. Turn adjusting screw/air bleed screw clockwise until engine is 850 RPM.
Dwell meter reading should be 31-33 degrees. Tighten lock nut on adjusting screw/air bleed screw. Turn engine off. Check TPS adjustment. See THROTTLE POSITION SENSOR (TPS) ADJUSTMENT . Adjust throttle dashpot. See DASHPOT ADJUSTMENT .

RENDER: 1.0x

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When to See a Mechanic

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

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