944 Vibration question

thill944 · thill944's Garage

When my 87 944 is at idle I have a very bad shudder/vibration. When I give it gas and the rpms go to around 1100 the car is as smooth as silk. I have only had the car a few weeks so I don't know much of the history about it. My first take is that possibly the balance shafts are slightly out of adjustment. But I also notice that the idle RPM's fluctuate between approximately 800 to 900 rpm (constantly when at idle) This could possibly be a bad Idle Stabilizer. What do you think?

Thanks Terry

flash968 · 07-20-2009, 07:21 AM

probably a motor mount

John_AZ · 07-20-2009, 07:37 AM

Hi thill944 & welcome.

See 5.6.2
http://www.connact.com/~kgross/FAQ/944faq05.html

NOW
Pelican Parts our sponsor and your parts supplier if at all possible, sells motor mounts for either $32 each or $123 each. HUH???? OK, the cheaper MM will last a couple of years and the OEM will last a lot longer and continue to give you a frim ride with no vibration. EBay sells the cheaper set for about $100 a pair, again they will last a couple of years.

Get a bolt kit or go to www.Clarks-Garage.com for info on motor mounts.

GL
John_AZ
1988 924S + 1987 924S

Icey1174 · 07-20-2009, 08:21 AM

This year when I took my car out I had the same problem. I found the vacuum line worked itself off the fuel pressure regulator. Exact same thing that you are experiencing. I put it back on the FPR and I maintained about 850 to 900 RPMs and it is smooth again. The RPMs do not fluctuate anymore, it's just somewhere in that range.

Icey1174 · 07-20-2009, 08:25 AM

Also, I would guess if your balance shafts were out that the vibration would at least stay the same or get worse with higher RPMs.

Someone just had a good post about checking the simple things first. Try the vacuum lines. They are easy enough to play with. There is also a part of the vacuum line that is known to dry rot under the intake manifold.