Jump to content

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)

Cold idle problem

Recommended Posts

I have a 2002 996 3.6l Carrera and when cold, it idles, but giving it any gas makes it bog down and the revs drop, similar to a carbed engine with the wrong choke setting. Once the engine reaches normal operating temperature it runs fine. I'm guessing a temp sensor is faulty and the fuel mixture the engine is getting is incorrect for its temp. Has anyone else experianced this and how can I diagnose the problem, I have an OBD 2 reader but it isn't showing any codes. I have cleaned the throttle body and MAF and no improvement.

Link to comment
Share on other sites

From cold, intake air temp 46F: Air flow 1.455 lb/min, LTFT B1 was -4.2, B2 was -14, STFT B1 was 0, O2 B1S1 was 0.8257v

at ECT 98F: Air flow was 0.760, LTFT B1 was -0.7 B2 was -9.3, STFT B1 varied 1.5 to 5, B2 varied 4.56 to 9.3

at ECT 108: Air flow was 0.735, LTFT B1 was 0, B2 was -7.8, STFT B1 varied 0.7 to 3.9, B2 varied 3.1 to 5.4, O2 varied 0.105 to 0.660

at ECT 123: Air flow was 0.694, LTFT B1 was 0.7, B2 was -6.2, STFT B1 varied 0 to 3.9, B2 varied 0.7 to 4.6, O2 varied 0.1 to 0.675

at ECT 140: Air flow was 0.661, LTFT B1 was 1.5, B2 was -6.2, STFT B1 varied -2.3 to 1.5 B2 varied -1.5 to -0.7 and O2 0.150 to0.7

At 140 degs the hesitation was gone.

Link to comment
Share on other sites

Have you checked your air filter for clogging or your air filter box for leaves, debris, etc.? It could be as simple as that.

Try starting the engine from cold with the air filter removed (and the air filter box clean). If it changes the idle behavior, replace the air filter.

Regards, Maurice.

Link to comment
Share on other sites

  • 4 weeks later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • 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.