Cleaning the IAC valve on the Saab 9000 turbo (Trionic models)
The engine idling speed on the Saab 9000 is controlled by an electrically operated idle air control (AIC) valve, also referred to as an automatic idle control (IAC) valve on some models. One end of this valve is connected by a rubber hose to the air filter side of the throttle plate, while the other end is connected by a rubber hose to the engine side of the plate. By varying the opening of the valve, the engine management system can vary the amount of air (and fuel) supplied and maintain an appropriate idle speed regardless of engine load, for example from the air conditioning system.
This procedure deals specifically with turbo models fitted with the Trionic engine management system, and without traction control. There are some differences on other models, but I have no experience of them. The information here may be of some use to owners of other models, though. Specifically, on the B202 (2.0 litre engine without balance shafts), the valve is mounted on top of the inlet manifold and is readily accessible.
The reason I undertook this procedure was that my '96 Aero had been idling
erratically for some time, and one day refused to idle when started after a
short stop. Using the throttle to keep the engine running resulted in the engine
idling erratically between about 2500-3000 RPM. Cleaning the valve (after around
160K miles) cured this completely and the idle is now smooth and precise.
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All information is presented in good faith. However, I am not a trained mechanic, just an enthusiast.Therefore, it is your responsibility to ensure that you are competent to carry out any procedures presented here and that they are correct. No responsibility can be accepted for any inaccuracies or consequential loss, injury or damage.
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