Date: Fri, 21 Sep 2007 18:50:55 +0100
From: "Charles C." <c.k.christacopoulos.removeme.nospamee.ac.uk>
Subject: Re: Intermittent engine vibration


Doug Schwarz wrote: > I have a 1995 900S with an intermittent engine vibration. It appears to > be related only to engine speed and it comes and goes. Here are my > observations: > > 1. I notice the vibration mainly through the gear shift lever and the > gas pedal. > > 2. When it first started it would exist for an entire trip and then be > absent for another entire trip. Now it seems to start and stop during a > trip and the amplitude varies, i.e., it's not the same intensity all the > time, but you definitely can notice when it's there and when it's not. > > 3. It feels and sounds a bit like a hole in the exhaust system, but the > character of the sound does not change with the throttle. It will be > present at idle. If I get up to speed, press the clutch and then rev > the engine back up to the cruising rpm the vibration feels exactly the > same. As a result I conclude that it's not related to the tires or > other drivetrain components after the clutch and also not a hole in the > exhaust system. So it should happen with the car stationary. > > 4. It seems to peak in amplitude at about 3200 rpm. Ignition, any vacuum pipes. There is a possibility that the vibration is there after 3200 rpm but its frequency is such that you can't tell. > > 5. The other day I did quite a bit of driving around town on a hot day > (about 82 deg. F) and the vibration was absent so maybe it's temperature > dependent. > > > I called the local dealer and the service advisor said he'd never heard > of anything like that before. I didn't get a chance to talk to a > mechanic. Does the car have a Direct Ignition cassette? :-) Sorry, I had to have mine replaced recently (1997 9000) with the symptoms being mainly a misfire (there is vibration for you) and having got the new one I have realised that the car was rough for some time now ... but I could not tell. One approach is to drive the car until it gets worse. :-( Charles -- Please remove _removeme_ to reply.

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