Subject: Re: New Vanos rings- increased fuel consumption? Author: webhorn4477 : member since November, 2009 : 45 posts Posted on: 2010-01-25 08:20:37

Oops, overlooked your post, sorry.

At first, we should explain our definitions about fuel trim to make sure we are talking about the same things:
When you read the DME fuel adaption with INPA, you get three different values:
-Lambda integrator Bank 1/2 (this would be the short term fuel trim)
-Adaption value additive Bank 1/2 (this is the long term idle fuel trim, measured in miliseconds injection time deviation of programmed engine injection map)
-Adaption value multiplicative Bank 1/2 (this is the long term fuel trim for partial load, measured in % deviation of programmed engine injection map)

You wrote: "A positive number greater than 3% is an indication of a lean mix and this is often caused by a vacuum leak."
Are you sure about the vacuum leak? To me, it seems logical that a vacuum leak shows most clearly at idle, because the intake vacuum is the greatest. (The greater vacuum when coasting of course does not count, because no combustion happens there). And at idle, everything is fine... If you are right: Where could this leak be when it shows only under partial load and not at idle? CCV system? Or, as you said, malfunctioning MAF sensor?

You wrote: "The long term fuel trim adjustment percentage values should be less than +/- 3%"
Are you sure about the +/-3%? I once had a .pdf issued by BMW describing the functions of the fuel adaption on M52TU and M54 engines, which i sadly lost due to a HD crash. I´m quite sure they were talking about +/-20% there before actions have to be taken and a fault code is set...

You wrote: "Are you using OEM sensors, including the MAF?" Of course I am ;-) Strangely enough, my intake camshaft and crankshaft position sensor are still the first ones that came with the car (they have the production date on them), they usually don´t last that long. I only replaced the exhaust cam sensor with an OEM part- not because it was malfunctioning but because it was leaking oil.
I changed the MAF sensor when i got the car, just to make sure everything is fine, because the previous owner had been running an oiled K&N air filter insert. When i put the old MAF in, it makes almost no difference whatsoever to the engine running charakterisitics or adaption values.

Where do you have the info about the +/-3% from? If you´re right with that, that could be the clue for me for further investigation. I still somewhat suspect an aging fuel pump....

webhorn

• New Vanos rings- increased fuel consumption? - webhorn4477 2010-01-24 18:39:24 (1137 views)
  • Re: New Vanos rings- increased fuel consumption? - Rajaie 2010-01-24 22:00:24 (627 views)
    • Re: New Vanos rings- increased fuel consumption? - webhorn4477 2010-01-25 08:20:37 (685 views)
      • Re: New Vanos rings- increased fuel consumption? - Rajaie 2010-01-26 16:55:10 (579 views)
        • Re: New Vanos rings- increased fuel consumption? - webhorn4477 2010-01-27 08:55:18 (622 views)
          • Re: New Vanos rings- increased fuel consumption? - Rajaie 2010-01-27 16:22:50 (429 views)
            • Re: New Vanos rings- increased fuel consumption? - webhorn4477 2010-01-27 19:52:45 (424 views)
              • Re: New Vanos rings- increased fuel consumption? - koveras 2010-03-17 12:55:32 (416 views)
                • Yes, i did. See... - webhorn4477 2010-03-17 18:11:01 (393 views)
              • Ok. Let us know how things go (nt) - Rajaie 2010-01-28 20:16:58 (454 views)
  • Re: New Vanos rings- increased fuel consumption? - poolman 2010-01-24 19:06:05 (521 views)
    • reply@poolman - webhorn4477 2010-01-24 19:34:16 (461 views)
      • Re: reply@poolman - poolman 2010-01-24 20:26:06 (427 views)
        • Re: reply@poolman - webhorn4477 2010-01-24 20:43:17 (785 views)
          • Re: reply@poolman - Rajaie 2010-01-24 21:54:39 (457 views)
            • Re: reply@poolman - webhorn4477 2010-01-25 07:11:21 (461 views)
              • Re: reply@poolman - poolman 2010-01-26 19:36:01 (393 views)
                • Technically not... (pic) - ZetaTre 2010-01-27 17:26:42 (472 views)
                  • Great shot - poolman 2010-01-27 22:02:54 (410 views)
                    • Yea, but that's with the head off... - ZetaTre 2010-01-28 16:34:50 (379 views)
              • Re: reply@poolman (pic) - ZetaTre 2010-01-26 17:18:06 (458 views)
              • Thanks for the super info! (nt) - Rajaie 2010-01-26 15:41:51 (423 views)
              • Re: reply@poolman - poolman 2010-01-25 08:01:51 (396 views)