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Re: 99T lack of power Posted by JohnT [Email]  (#1654) [Profile/Gallery]
(more from JohnT) on Wed, 19 Feb 2003 23:19:04
In Reply to: Re: 99T lack of power, Miles Muri, Wed, 19 Feb 2003 15:31:59 Members do not see ads below this line. - Help Keep This Site Online - Signup |
OK, now I would check two things. The distributor and the ECU.
You can check the ECU pretty easily by simply plugging in another one to see if it works. According to my info, the same ECU was used on all 99 & 900 models with breakerless ignition from '78 to '83, both turbo and n/a. So it shouldn't be too hard to find a used one to try. (Sorry, I haven't a clue how it works or how to test it electronically. If you need me to, I can scan the pages out of the manual and maybe your mechanic will know what to do).
The other thing to check is the distributor. Like most older distributors it uses a centrifugal advance at low rpm, then the vacuum advance takes over. The turbo distrib is unusual in that it uses manifold vacuum to advance the timing at mid-range rpm, then at high rpm when the manifold is pressurised by the turbo, it starts to retard the spark to avoid pinging. At least this is how the Saab service manual explains it. So anyway I would make sure that the air line from the manifold to the distributor vacuum is not clogged or broken. Also make sure it is connected to the right place at the manifold. It has to connect to one of the barbs directly over the throttle valve for the pressure to be right. I'm not sure how you would test the vacuum unit except to make sure it doesn't leak.
One other thing: make sure the timing is set to 20° BTDC @ 2000 rpm with the vacuum disconnected & plugged. That seemed like a lot to me but that's what the manual says.
Well if none of that works I don't know what to tell you. I'm not a professional mechanic but I sure like a good Saab puzzle! Seems like you get a lot of them with the turbo. Keep us posted.
posted by 66.169.88...
, Wed, 19 Feb 2003 23:19:04 <-- Viewing This Message, Sun, 2 Mar 2003 22:46:40, Fri, 14 Feb 2003 14:20:12, Thu, 13 Feb 2003 11:02:21
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