951 VIOLENT idle and a few other things.

[perfecto951]

(1986 951 110Kmiles)

1) Ok, I have read about all there is to read about a rough idle on this BBS. My balance shafts are fine, new belts, seals, ect. Even after those parts were replaced the rough idle has continued. The shafts are aligned properly.

And this isn't just any normal rough idle, the steering wheel shakes and makes a loud noise because the whole car shakes so bad. The seats feel like vibrate so much it feels like something you would have bought them from Brookstone or Sharper Image. I can't see out of any of my mirrors due to the vibration.

When i depress the pedal the vibration ceases about 1,600 RPM. Not totally, but the very good majority of it. I have checked all that i can think of, i have looked for boost leaks, cleaned my injectors, cleaned all my plumbing, air filter, ect. Everything i can do i have done except one thing. The fuel filter looks like it has 70-80 thousand miles on it. I am going to replace it tomorrow, however i seriously doubt that will be the problem. The car runs pretty well with the exception of that. Could a clogged fuel filter do this? I haven't checked engine compression, but i guess i ought to.

2) Now another thing that relates to the above. I was curious if everyone else with a 951 can listen up front near the re-circ valve (blow-off, whatever) and hear a distinct whistling noise when you depress on the throttle body. Right when you give it a little rev it whistles just a bit and then it can't be heard over the engine noise...perhaps that may be part of the problem? I would guess there is a little crack in my rubber "J" shaped boot there - but surely that couldn't create such a problem with idle.

3) And another.... When the clutch pedal is completely out you can hear a loud squeaking. If you press it in just until you feel the resistance of the main spring the noise goes away. I have been told it could be my Throw-Out barring. I was thinking that maybe if i adjusted the clutch pedal down to where it doesn't make any noise it would stop.... problem with that is i would be worried about wearing my clutch down to nothing if it is engaging the slightest bit.

4) Ok, last thing. Pretty minor, but it bothers me a bit. My "gas low light" stays on, but my gauge works fine. Is there a float in the tank that would get stuck or go bad, or is it electrical possibly?

Everything but #4 is old. I have lived with these problems too long and I’m tired of it. I just want my 944 to work! Thanks guys you are always a great help.

-Jamie

[perfecto951]

thanks. shouldn't be too terribly difficult to install with the right tools. i guess i should buy a pair of OE mounts?

[Pike]

_ It could very well be motor mounts, however, I had a bad (not as bad as yours) idle shake that was fixed by checking timing and cleaning the injectors. One was not giving a good spray pattern at low RPM, once I gunned it, the shake went away because the spray evened up (higher pressure for the injector. Unfortunitly, I don't think that you have the same injection system I have (CIS).

[944pete]

If it smooths out around 1400 to 1600rpm as you say I would bet money on motor mounts. Do not, I repeat, do not buy the cheap ($60 or so) aftermarket mounts. They will last a few thousand miles and you'll be right back here again with the same problem (ask me how I know). The OEM Porsche mounts are around $100 each but they will last a long, long time. This isn't the most fun job so you don't want to do it twice.

[perfecto951]

sweet. i ordered new OEM mounts. and i replaced my fuel filter. oddly enough it idles more evenly. but the wheel shill feels like it's goin to come off. i inspected the mounts and they look collapsed from what i can tell.....and coated in oil.

[ilikemy944]

I saw your car at the mall a few days ago
Good luck with the mounts, hope that does it!

[ilikemy944]

BTW, my buddy and I plan on hitting some northern curvy roads in a few weeks... I guess I'll call later and let you know the specifics.