Date: Fri, 19 May 2000 15:17:51 -0700
From: Tom Reed <>
Subject: lack of boost in 900T

Hi all, I'm having a vexing time trying to figure out why I can't get any boost out of my turbo. I'm hoping someone can help me interpret my results so far. Car is an '85 900T 16v. It's just not getting boost (perhaps 2mm into the yellow area on the gauge), but the turbo itself seems to be functioning correctly (at least I can hear it spin). Here's what I've already tried (after reading through the archives at Deja) 1) Checked for back-pressure by disconnecting the exhaust upstream of the cat and muffler. No effect (but it did sound really cool). 2) Pulled the APC fuse. No effect (so I put the fuse back). 3) Disconnected the vacuum hose between the solenoid valve and the wastegate actuator (or whatever that thing right below and in front of the turbo is called). Resulted in more boost than I'd ever seen. So... what does this mean? I'm thinking that the wastegate may be stuck open, but if it is I can't hear it (at least not from inside the car while driving). Is the wastegate actuator bad or is it something else entirely? A little more info: a few months ago I tested the solenoid valve (connected it to 12vdc); it opened and there wasn't any chattering. A few weeks ago (after having a similar problem) I found one of electrical leads to the solenoid valve disconnected. I plugged it back in and boost levels were fine... for about a day. Now this problem. It doesn't seem to be the same problem, though, because with the solenoid disconnected I was having drivability and overheating problems, which I'm *not* having now. And a possibly related (or not) problem: whenever I've been driving for some distance without stopping (ie. on a freeway or even if I just hit the stoplights right), the idle is way too high when I first come to a stop. Is this the AIC valve or something else? Does anyone have any ideas, or should I just go see my friendly Saab expert mechanic? I hope I don't have to, because he's expensive. Thanks for any replies. Tom R. "The best book on programming for the layman is Alice in Wonderland, but that's because it's the best book on anything for the layman." --Alan Perlis

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