[Caracal]

I have a 1993 Porsche 968 which has a vibration problem. The car vibrates at idle and up to 1300 rpm. It gets worse when I put the car in drive and even worse still when I turn on the a/c. If I rev the car to 1300 rpm it is nice and smooth even in gear and with the a/c on. Any ideas as to the cause? The engine mounts were replaced two years ago. I am unsure if they were Porsche or aftermarket.

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[flash]

ah - i didn't read that it was a tip in the other thread - that could put it in the trans - those flex plates are known to fail

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[rustech]

How's that ISV (Idle Stabilizer Valve)? Vacuum leak? These things would be overshadowed once the throttle body opened up which would be why you would only feel it at the low rpms.



Edit: Poor ignition wires also tend to have a larger effect at the lower rpms.

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[Greimann]

It does sound like the symptom of bad motor mounts.

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[Cloud9...68]

[quote name='Greimann' date='Apr 8 2006, 08:17 PM']It does sound like the symptom of bad motor mounts.

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Agreed. My car has the same problem, and I'm in the process of changing the mounts now (stuck at the moment trying to get the top bolts to align - the engine shifted a bit when I raised it, so I'm taking a break hoping to get a flash if inspiration as to how to shift this engine while on the jack to get the bolts to align). I'll let you know the impact on the vibration when (hopefully) I figure this out.



As another input, I noticed that the two top bolts on my left engine mount were VERY loose. Not sure if this by itself could have caused the significant vibration my car has (had?) at idle, but you might want to try to get a 13 mm wrench on these bolts, as well as checking the 17 mm nut that attaches the mounts from below to the cross-member, and check the tightness. In my case, I already had the swaybar off, the control arms moved aside, and the right mount removed, so I went ahead and continued with the mount replacement. Wish I had thought to check the bolt tightness before I started, though. Good luck.

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[Caracal]

I'll crawl under there tomorrow and see what I can find. Thanks for the input.



Cloud9...68, Did your's smooth out at around 1300 rpm? I hope you don't have much trouble getting everything lined up. Let us know how it goes.



Andy

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