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)

Emissions Fail

Recommended Posts

Took the 986 for its MOT yesterday and filled up with 97 RON fuel rather than the usual 95 RON just before (long story) so that it went into the test with probably a 60:40 mix of 97:95

Would this (dumb) fuelling error have contributed to the following awful emissions numbers? No current CEL lights and the car seems to drive fine at the moment.

2500-3000 RPM

CO 5.09% actual 0.30% Max

HC 413ppm actual 200 Max

Lambda 0.91 actual 0.97-1.03 Allowed

These numbers seem to say to me that the fuel/air mix is too rich. If it is not the fuelling mistake any suggestions as to where to start (I would have said cats but the low Lambda number doesn't seem to be consistent with that; if it were those I would expect the Lambda figure to be too high).


Link to comment
Share on other sites

Hi, got out the Durametric and got the following fault codes:

P0154 O2 sensor ahead of cat

P1115 Resist limit O2S ahead of cat B1

P1119 Resist limit O2S ahead of cat B2

P0134 O2 sensor ahead of cat bank 2?

Cleared them and rebooted the software a couple of times but only P0130 O2 ahead of cat conv bank 1 appeared after that.

Other readings:

O2 sensor voltage 0.14V steady and 0.08-0.67V fluctuating

FRA 1.28/0.94

TRA 0.08/-0.06

MAF 1.35V 14.5 kg/h @ idle; 1.92V 44kg/h @ 2500RPM

The readings seem to point to the right hand O2 sensor being dodgy, but the reoccurring code seems to point to the left hand one...

Over to you, and TIA.

Link to comment
Share on other sites

Yes, engine was up to temp. I replaced the sensors about 3-4 years ago with a couple of cheap and cheerful ones. This time I'm going to get a couple of Bosch ones.

Thanks to you both for your help. And also Durametric for their code reader -- it proved useful a couple of years ago when I had a couple of ABS sensors pack up.

Suspect that I'll have to replace the cats as well: they are 14 years old now and all that HC contamination will not have done them any good...

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.

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.