Date: Thu, 12 Sep 2002 16:37:04 GMT From: Paul Halliday <pjghnopsamyonder.co.uk> Subject: FIXED: Violent Vibration at 50-60 MPH
Hi again, Thank you everybody who has given me hints and tips about this problem. It is now resolved. The car in question was a 1989 900 Turbo S, experiencing a violent shudder at 50MPH, which disappeared at 60MPH. I spend an hour or two the other day "tinkering" under the bonnet, giving my Saab the kind of TLC that garages do not. Among other things, such as checking the tightness of the sparks (which were okay), filling down the crap that builds up on the rotor arm, WD40'ing the electrical contacts, refreshing jubilee clips, checking the tightness & condition of all air hoses and so on I noticed two distinct problems with the air intake. 1. The air scoop pipe was not actually connected to the air filter!!! Needless to say, I reconnected the pipe and tightened it up. 2. There is a T-junction just below the recirculation hose from the APC solenoid that connects up to the throttle intake with a narrow half centemetre pipe and another wider hose that runs off into the engine bay. [Sorry, I'm not that mechanical so a vague description will have to do] This T-junction is connected into the pipe that runs from the air filter box into the turbo-charger. This T-junction is held into the pipe with a rubber grommit. On my car, it had worn and was actually being pushed aside by some electric wiring and other gubbins. I re-routed all the bits that were in the way and secured it down with a cable-tie around the turbo pipe. I furthermore secured the recirculation hose with a couple of cable ties and took the car for a drive. Well, what do you know??? ... handling, clutching, braking and turbo performance was vastly improved. The shudder at 50MPH was barely noticeable - infact, if you were not expecting it, you wouldn't notice it. Gone ... The APC gauge on the dash indicates that the turbo is boosting to around 3/4 up the yellow zone and staying there until about 3500 RPM, where is drops slightly. I also feel the "turbo mule kicking me in the back" again, which is huge fun. I got a lot of quick tail-off before which was disappointing. So, I think I know what the problem was :) Either, WD-40'ing all the electrical contacts, or tightening up all the air hoses, with particular attention to the turbo pipe, has made the difference. My cludges will, of course, be remedied when I take the car to my garage next time [a few new rubber grommits, please Mr Mechanic]. BTW, does anyone know of a good silicon hose retailer in the UK? I've a couple of pipes with "wizard's sleeve" ends secured with jubilee clips that I'd like to replace. Thanks again to everyone who has suggested possible fixes for this problem ... now where's my other APC box and a screwdriver ... time for some pot tweaking :) Keep on Saabing, Paul 1985 900i 16V 1989 900 Turbo S http://pjgh.go.dyndns.org/saab/index.html
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