Idle Speed Adjustment
How to adjust idle speed on 8V 944 and 944 Turbo models using the throttle body idle screw, with idle RPM specifications by market and instructions for defeating the idle stabilizer.
Introduction
Idle speed adjustment is not normally required on 944s. However, the idle speed adjusting screw occasionally backs out, causing the idle to fall out of specification.
Note: The 944S and 944S2 models use an "adaptive idle speed volumetric efficiency regulation" system and do not require idle speed adjustment via this procedure.
Tools
- Flat-tip screwdriver
- Wire jumper with round male connectors, or Special Tool 9246 (1985.5 and newer models)
- Temperature measuring device for engine oil
Idle Speed Specifications
| Vehicle | Idle Speed (RPM) |
|---|---|
| 944 (Europe) | 800 +50 |
| 944 (USA/Canada/Japan) | 900 ± 50 |
| 944 (Australia/Sweden) | 800 +50 |
| 944 Turbo (all markets) | 840 ± 40 |
For vehicles with automatic transmissions or power steering, adjust to the upper limit of the specification range.
Procedure
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Turn off the fan motor and A/C compressor before adjusting idle.
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Start the vehicle and run at idle to warm the engine. The factory specification calls for the oil temperature to be between 70–90 °C (158–194 °F). A contact temperature gauge on the bottom of the oil pan can be used as an alternative to the factory dipstick-tube temperature probe. If neither is available, run the engine for approximately 10 minutes after the coolant reaches normal operating temperature.
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On 1985.5 and newer models, defeat the idle stabilizer by installing a jumper wire between terminals B and C of the diagnostic plug (see diagram). If you have Special Tool 9246 (Test Relay), use it instead — the idle stabilizer is defeated when the green lamp on the test relay is lit.
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Using a flat-tip screwdriver or 7 mm (9/32") socket, turn the idle speed adjusting screw until the idle is within the specification for your vehicle.
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If the idle adjustment screw has a history of backing out, apply a small drop of silicone sealant on top of the screw after adjustment to prevent future movement.