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Discussion Starter #1
I recently lost my idle control on my '89 900 sport. I have an LH 2.2 ECU from an '86 900 turbo, since my car was converted to a turbo. My idle dropped to about 250-500 rpm when warm and won't even idle when it is cold. I discovered that the ECU is not sending any output signals to the AIC valve, and the AIC valve is apparently stuck shut resulting in an extremely low idle. I discovered that it was my ECU causing the problem, not the AIC valve when I decided to swap my ECU out for another matching ECU, and this fixed the low idle issue.

My question is this. Is it possible to repair my ECU with the faulty idle control? Other than this problem, it is a perfectly functioning ECU and I would hate to see it go to waste. Is this a common problem, that anyone else has expereinced? Could I possibly have some bare wires somewhere in the wire loom causing some sort of short in the AIC valve wiring. Would this result in a fried idle circuit in the ECU?

Any help would be great. Thanks!!
 

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That sounds like the same problem my car just started having. A lower-than-normal lumpy idle, and dies when cold. Hmmm....
 

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JGaren said:
That sounds like the same problem my car just started having. A lower-than-normal lumpy idle, and dies when cold. Hmmm....
The symptoms you desribe are very common and are usually caused by a vacuum leak. A faulty ECU is far less likely to be the problem. I had variable idle a few days ago, checked all vacuum hoses and connectors and then cleaned out the AIC valve with carb cleaner followed by WD40, which fixed the problem. There's a guide here.

Welcome to Saab Central :cool:
 

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Discussion Starter #4
I know it is definately not an air leak, because as soon as I swapped ECU's the problem was gone. normally the AIC valve should be vibrating and making some noises and when you pinch the AIC vlave hoses the idle should get slower. The valve was making no noises and was simply staying shut. I know it was shut, becuase when I pinched the hose the idle didn't change at all. It's a faulty ECU, just wondering if anyone here has had the same problem.

Thanks!!
 
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