Cleaning the IAC valve on the Saab 9000 turbo (Trionic models)

Introduction

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.

Time required

30 minutes.

Tools required

• Flat-bladed screwdriver to fit the hose clips.

Procedure

1. Release the clip and remove the rubber air duct from the throttle housing.
   
   
   
   
2. Locate the IAC valve below the inlet manifold.
   
   
   
   
3. Release the clips and remove the upper hose from the IAC valve and the throttle body.
   
   
4. Release the clip and remove the lower hose from the throttle body.
   
   
   
   
5. Slide the rubber mounting off the mounting peg. It may be necessary to prise it off with a screwdriver. Be careful not to strain the wires as the mounting comes free.
   
   
   
   
6. Press in the spring clip on the connector to release it and unplug the connector from the valve. Lift the valve clear, complete with lower hose.
   
   
   
   
7. Release the clip and remove the lower hose.
   
   
8. Clean the valve by spraying carburettor/throttle body cleaner into both ends.
   
   
9. Refit the lower hose, but do not tighten the clip yet. If you have removed the rubber mounting, note that the valve must be refitted with the arrow pointing upwards.
   
   
   
   
10. Refit the connector and refit the rubber mounting onto the mounting peg..
    
    
11. Refit the lower hose to the throttle body and tighten both clips.
    
    
12. Refit the upper hose to the IAC valve and the throttle body and tighten both clips.