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Date: Mon, 08 May 2000 21:40:43 +0200
From: RCS <e9225126nopsam1.tuwien.ac.at>
Subject: Re: engine stalls on 900T16


The same problem every time on the 900! Iīm absolutely sure that itīs the same thing! Originally this problem starts at the front engine rest (sometimes the rest also breaks, you īll only notice that at an awful cruise driving at idle 1st gear) thatīs too weak and allows a too large up/down movement of the engine against the chassis. Thatīs the reason why the air intake pipes in front of the engine right after the radiator get loose or rub against other parts. After some years there are holes at the air intake pipe (at my car even a screw of a pipe connetor worked through the alloy pipe!!!). The air mass meter that tells all other components what to to is located in front of this holes so the metered air mass is wrong. That confuses the control of the AIC valve (Automatic Idling Control valve, a bypass of the closed throttle plate that keeps the engine running when the pedal is released). The engine stalls when you release the pedal after normal driving (traffic light, or it works better when you rev higher and abruptly release the pedal ) cause the throttle closes and the AIC opens, opens, opens until itīs closed on the other side. Sometimes also the AIC valve itself gets dirty and sticks but you can see this only when you drove on highways for a longer time and the idling is much too high when you left the highway. But over 90% there are leaks in the air intake pipes that cause rough starting, and unstable idling especially after starting the car like 3000rpm down to nearly stalling, 2800 rpm down to 500, up/down.... If you donīt know this itīs difficult to find it cause the engine management system is adaptive learning. You can change or adjust anything, everything is fine for a while cause every part is running in safe limits and adjusts a new operating point - then happens the same again. I have a very good SAAB mechanic but it took us nearly half year to locate the exact problem! Never change any part if you are not 100% sure itīs faulty (and itīs never the expensive APC unit), itīs no mistake to change the AIC potentiometer/switch cause it fades anyway. Greetings, RCS 1993 900 turbo convetible Werner : > I have noticed the following problem on my 1991 900T16: when driving very > slowly (city driving) or idling the engine sometimes stalls ans shuts off (I > see the revs go to zero). Same problem when I start the car: the revs go > up, drop to zero and the engine tries to keep the engine going and it does > most of the time. I suppose it has something to do with stationary idle. > Someone told me to take out the little part (don't know the name of it) that > controls the stationary idle and to clean it and I did but no much effect. > How do I know if this part is broken? Any way to check this? Or should I > go and look for other causes like problems with the APC box? > On the other hand I have no problems when driving at normal speeds, only > when slowing down for traffic lights or in city driving the engine sometimes > shuts off. > > Any comments greatly appreciated! > > Thanks, > > Werner

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