Subject: Re: Increased fuel consumption: issue resolved- but no logical explanation... Author: henrikk : member since February, 2010 : 16 posts Posted on: 2010-03-07 15:44:17

Hi again webbhorn4477, sorry for the delay and sorry for my very bad explanation.

Webbhorn447 wrote: > That is also the reason why there are O2 sensors- to check the exhaust gas wether the correct mixture is achieved, and, if not, make the engine computer correct it. Luckily, this proportion of air/gas is also almost the best compromise for engine performance and fuel economy.<

You describe exactly why DME must correct the gas mixture and of course DME relies of the data sent from the engines sensor. The fuel and ignition computer in snowmobiles does the same thing and always compensate the fuel mix for the altitude. It is hard to believe that BMW DME is missing that function. In higher altitude more gas is needed to compensate for the lack of air this will save the catalytic converters in long terms. Less gas will always create more heat. Vanos is the function that will protect the catalytic converters. This will secure the engine from overheating and the safety of engine operation. Electronic fuel injection circuit with altitude compensation is not a new function and it depends on the MAF and a second electrical sensor absolute temperature MAT.

My guess is that you have a MAF sensor glitches. If that the case the DME will go to safety mode. That mode will restrict the engine and pump more gasoline to protect the engine.

Mixture of 14.7 and one part gasoline is what every car computer trying to blend. Most of to days modern car computers has rules that’s protect the engine when faulty values or values is out of range.

Your explanation according the mixture 14.7 is the standard rule for every car computer. Sorry but moisture in the air and the temperature and altitude is to dynamic even for to days car computers. Mixture 14.7 to one is in theory the best mixture but that mixture will never happen in a car combustion engine.

A perfect mixture of two tablespoons of gasoline and air holds enough energy to blow up two streets. And yes mixture 14.7 to one is the best for emissions and combustions engines not for energy outtake. Mixture 14.7 to one applies to combustions engines.

This is not confirmed but what l heard from BMW DME will always protect the engine even if the emission gets out of range temporary. That happened to me once and the answer from BMW was clear. O2 sensors and catalytic converters can be sacrificed in some circumstances. Witch circumstance is unclear.

I read that you got the same symptom as me after you installed new vanos seals. I got a warmer valve cover witch l think is the solution for the sludge in the crankcase ventilation. Any way it is great to hear that I am not alone with that side effect.

• Increased fuel consumption: issue resolved- but no logical explanation... - webhorn4477 2010-02-28 19:02:13 (798 views)
  • Re: Increased fuel consumption: issue resolved- but no logical explanation... - henrikk 2010-03-01 09:59:46 (535 views)
    • Re: Increased fuel consumption: issue resolved- but no logical explanation... - webhorn4477 2010-03-01 17:41:56 (500 views)
      • Re: Increased fuel consumption: issue resolved- but no logical explanation... - henrikk 2010-03-07 15:44:17 (445 views)
        • Re: Increased fuel consumption: issue resolved- but no logical explanation... - webhorn4477 2010-03-17 18:51:08 (378 views)
          • Re: Increased fuel consumption: issue resolved- but no logical explanation... - henrikk 2010-03-22 08:04:59 (326 views)
            • Re: Increased fuel consumption: issue resolved- but no logical explanation... - webhorn4477 2010-03-22 15:40:54 (413 views)
  • Re: Increased fuel consumption: issue resolved- but no logical explanation... - Rajaie 2010-02-28 23:36:33 (496 views)
    • Found even better mileage! - webhorn4477 2010-03-19 07:11:37 (453 views)
      • Re: Found even better mileage! - webhorn4477 2010-03-19 22:20:26 (466 views)
      • Re: Found even better mileage! - poolman 2010-03-19 12:21:20 (369 views)
        • Re: Found even better mileage! - webhorn4477 2010-03-19 22:25:57 (440 views)