Subject: Re: New Vanos rings- increased fuel consumption? Author: webhorn4477 : member since November, 2009 : 45 posts Posted on: 2010-01-27 08:55:18

You wrote: "I have noticed from reading multiple cars that a good LTFT adjustment percentage is less that +/- 3%."
I like that- values from "the real world" with lots of experience from reading good and bad running cars. Will try to reach the 3%.

You wrote: "I wonder if your large LTFT adjustments values, the engine pinging, and the oil burning are all related."

I thought about that, too- afait there is a connection between oil consumption and pinging, not only because burning oil causes pinging-inducing deposits but also because oil in the cumbustion chamber reduces octane rating of fuel.


You wrote: "The new vanos seals might have exacerbated this problem and caused the increased fuel consumption."

I think so, too. As far as i have read (especially here), new vanos seals may uncover a problem with an engines mixture preparation that had been covered before.

You wrote: "If the engine is burning oil it's also likely importing not just oil but also air into the cylinder. The oil and extra air in the cylinder could cause the pinging."

I do not quite think so- it´s a good thaught though. Reason beeing, engine´s oil consumption is the greatest when coasting- but no combustion happens there and thus the oxygen sensors don´t get read out and no fuel adaption happens, and the cylinders are full of air, on every engine.
My english is probably not good enough to clearly express what i really want to say, but anyways: Though the engine consumes oil (consumption is still insinde manufacturers spec.), i should be able to get it to run right and economical.

Why i suspect a fuel starvation issue and not a vacuum leak:

1. From the experience with my ex E39 523iA w/M52TU engine, vacuum leaks do show most clearly at idle, in the so called "additive mixture" trim measured in milliseconds. This is the LTFT for idle and very low load running conditions.
This engine had literally every vacuum leak possible and it took me ages to figure everything out, because i didn´t know then what i know now.
It´s also logical that a vacuum leak shows most clearly on idle conditions, because the vacuum in the intake manifold is the greatest.

2. A vacuum leak that only shows under higher load conditions, can only be between MAF and throttle plate. Reason beeing, throttle plate is quite open, engine sucks in a greate volume of air, thus intake manifold vacuum is low, but due to the high suction on the air filter side of the throttle plate, vacuum leaks (i.e. crack in idle adjuster elbow) can now play an important role and let unmetered air in the engine. It then does not show in the abovementioned idle adaption, but in the so called "multiple active mixture" adaption, which is measured in percent and is the LTFT for partial load conditions.

My hoses from air filter to intake manifold are all perfectly fine.

3. For testing purposes, i do read out the DME live values via OBD while driving, with my laptop and an interface. When i drive a long distance with constant quite low speed (cruise control at 100 km/h ~60 mph?), my multiple active mixture adaption (LTFT for partial load) slowly drops down to about +4,x % on both banks. When i accellerate to a higher speed (170 km/h) and keep that constant via cruise control, the multiple active mixture adaption rises to about 8%. This can only mean, when the MAF and the hoses to the throttle plate are intact, the engine doesn´t get enough fuel when it needs a lot of it. Reason might be a clogged fuel filter (mine is fairly new), dirty/clogged injectors (never heard of that before on an BMW 6 cyl. engine), defective fuel pressure regulator (is, on the M54, installed on and changed with the fuel filter) or an ageing fuel pump, which can still build up enough pressure and deliver the amount of fuel needed for idling, but can´t keep up with the increased fuel need at higher loads which causes the pressure to drop.

I will assemble a gauge system, with which i can check the actual fuel pressure in the rail while driving. Let´s see what this shows.

Won´t do it until in a few weeks, atm it´s by far too cold out.

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 (684 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)