Jump to content

The RennTech.org community is Member supported!  Please consider an ANNUAL donation to help keep this site operating.
Click here to Donate

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)

Recommended Posts

MY99, 996 six speed.

With A/C switched off engine is a bit rough idle and noticable at inside.

With A/C switched on perfect idle (and slightly higher as without A/C)

No error codes shown on Durametric.

I cleaned the ICV and throttle body but no improvement. Any ideas befor buying a new ICV?

Link to comment
Share on other sites

When you say rough, is the idle wandering? Or is the engine just vibrating a little more than it does at higher RPMs. Does an empty passenger seat shake violently or just a little bit? Make sure the oil is topped off.

I'm not 100% on this and would wait for others to chime in, but if the ICV were bad you would most likely have a wandering idle - if it stays steady I doubt it's the valve. You could also try cleaning the ICV. if the engine RPM raises when you turn on the A/C and stays steady then it is probably doing it's job.

My humble opinon is that slight idle vibration is farily normal for these cars (and have seen threads describing the same thing which people say is normal), but there could be a littony of reasons for engine vibration, if there truly is a problem. I doubt you have these problems though.

Vaccum leak

AOS

DMF - does it change when you press the clutch in?

IMS bearing going out causing balance shaft to wobble - doubtful though since I've heard they just "pop"

Worn engine mount

Worn transmisson mount

Worn variocam pads? (not sure about this one, perhaps if severe enough?)

Scored cylinder causing one or more to be out of spec

Worn valve guides causing one or more cylinder to be out of spec

The above problems or others causing low compression causing one or more cylinder to be out of spec

Cracked coil pack or bad spark in a cylinder - likely to throw codes.

A lot of these things will throw codes "if they are bad enough".

Edited by logray
  • Upvote 1
Link to comment
Share on other sites

You're assumtion of my idle problem is correct. It is more a bad vibration, RPM is not bouncing noticably at all.

However passenger seat is shaking a bit without A/C on (750RPM) With A/C on it is on the RPM is at 800.

Reading your link it seems to be normal. Anyways I do suspect engine mounts, will try to replace those first.

Thanks, Rob

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.