Results 1 to 4 of 4

Thread: fuel/air mixture

  1. #1
    DonTom
    Guest

    fuel/air mixture

    I have a few questions about fuel air mixture.

    I know that while cruising, the ultimate air to fuel mixture is 14.7 to one. But what would be considered as a normal range at a cruising speed on the freeways?

    In my RV, I have an air mixture gauge on a switch to go to either exhaust pipe. I can also separately switch the O2 sensor that the ECM uses.

    But with a warm engine cruising on the freeway, no matter how I set either, my mixture gauge reads that it's 13 to one. Is this considered too rich?

    And I believe it is a bit rich, because I have had a "Too rich at O2 sensor" (OBD-1 code 45) a few times. Since then, I reduced the fuel pressure a bit and the code has not yet returned, but the gauge still reads as rich.

    And do newer (or freshly rebuilt) engines run richer than well broken in engines? There are not that many miles on this 400 CID GM SB rebuilt.

    And if I get the mixture closer to 14.7, will my MPG improve much?

    BTW, it runs perfectly as is.

    Next week I will put a few hundred miles on it. I have it already for a trip for the week and a half I have off next week.

    And Eric, it runs great with the more than one year old gasoline withOUT any Sta-Bil! But I will add some fresh gas in it before the trip and go through a few tank fulls before we get back.

    BTW, I see the gasoline price is coming down as long as it's 50 miles or so from SF. The cheapest we found today on the way home from Reno is $3.019. I expect it to be below $3.00 by next week in that area (Dixon, CA).

    BTW, are they still going to have the .9 cent nonsense when gasoline gets to a hundred bucks ($100.009) per gallon?

    Around here in SSF, still expect to pay about $3.65 per gallon of regular. Here in South SF, the price is even higher than in SF and I assume the highest in the country.

    -Don- (back in SSF)

  2. #2
    Vulture of The Western World Eric's Avatar
    Join Date
    Jul 2006
    Location
    The Land of The Edentulites
    Posts
    22,762

    Re: fuel/air mixture

    It is always better to run a little bit rich vs. too lean.

    And from everything I have read (and my own personal experience) an engine will run better if it's jetted/calibrated just a tad rich.

  3. #3
    DonTom
    Guest

    Re: fuel/air mixture

    "And from everything I have read (and my own personal experience) an engine will run better if it's jetted/calibrated just a tad rich."

    I wonder if they are normally leaner than what's optimum is because a bit lean is better for smog.

    -Don-

  4. #4
    Vulture of The Western World Eric's Avatar
    Join Date
    Jul 2006
    Location
    The Land of The Edentulites
    Posts
    22,762

    Re: fuel/air mixture

    Quote Originally Posted by DonTom
    "And from everything I have read (and my own personal experience) an engine will run better if it's jetted/calibrated just a tad rich."

    I wonder if they are normally leaner than what's optimum is because a bit lean is better for smog.

    -Don-
    That's what they used to do - fer sure! (Remember the Chrysler "Lean Burn" system from the '70s?)

    Also, many bikes seem to be jetted on the lean side from the factory; the aftermarket kits (jets or ECM reprogrammers) seem to always fatten up the mixture a bit...

Similar Threads

  1. Should I use fuel additives?
    By dom in forum Automotive FAQs
    Replies: 5
    Last Post: 11-27-2010, 05:28 PM
  2. fuel additives
    By pearly8 in forum Car Care & Repair
    Replies: 8
    Last Post: 03-01-2010, 06:57 AM
  3. Fuel Use RR
    By robmcg in forum Motor Mouth
    Replies: 3
    Last Post: 06-12-2008, 10:44 AM
  4. And Now We Grow Fuel?
    By robmcg in forum Motor Mouth
    Replies: 2
    Last Post: 03-20-2008, 09:43 PM
  5. Grease fuel!
    By Eric in forum Automotive News
    Replies: 4
    Last Post: 07-30-2006, 08:49 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •