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Thread: Mirage mileage readout A and B?

  1. #21
    Moderator Eggman's Avatar
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    Quote Originally Posted by Cobrajet View Post
    The injectors are shut off. It is called "Deceleration Fuel Cut-Off" (DCFO). On my Mirage the injectors kick back on at about 1200 rpm when I am engine-braking to a stop.
    Cobrajet, I've noticed the same thing and thought the injectors were also shut off. However, I recently got a bluetooth OBDII adapter that lets me monitor stuff while underway and I've noticed that I get high instant fuel economy numbers while coasting in gear but when I shift into neutral those numbers go up. It goes against what I thought DFCO was all about. Have you watched instant fuel economy while coasting? Maybe I'm missing something.


        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.0 mpg (US) ... 20.8 km/L ... 4.8 L/100 km ... 58.8 mpg (Imp)


  2. #22
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    Quote Originally Posted by Eggman View Post
    Cobrajet, I've noticed the same thing and thought the injectors were also shut off. However, I recently got a bluetooth OBDII adapter that lets me monitor stuff while underway and I've noticed that I get high instant fuel economy numbers while coasting in gear but when I shift into neutral those numbers go up. It goes against what I thought DFCO was all about. Have you watched instant fuel economy while coasting? Maybe I'm missing something.
    You have to be in gear for DCFO to work. It keeps the engine running by the energy of the car rolling. If you shift into neutral, you're disengaging the engine from that free energy and the car then has to find some other energy to keep the engine turning, so it switches to idle and kicks the injectors back on. if you want movement with no fuel you either have to leave it in gear while coasting or turn the key to shut the engine off completely.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage DE 1.2 automatic: 47.1 mpg (US) ... 20.0 km/L ... 5.0 L/100 km ... 56.6 mpg (Imp)


  3. #23
    Senior Member Top_Fuel's Avatar
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    Quote Originally Posted by Top_Fuel View Post
    My car has 21,000 miles and I have never seen/reset my car's lifetime average. Looks like it's pretty accurate in my case:

    51.4 mpg = Calculated lifetime average
    51.8 mpg = Computer lifetime "B" average
    Now that this thread has come back up, I need to clarify the above comment I made back in Post #10.

    My computer lifetime "B" average has been with 185-55-15 tires on the car. This causes the odometer to read about 2.5% lower than the actual miles traveled. So this may explain why most of you guys are saying the computer is off by 1+ mpg and mine appears to be more accurate.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 51.6 mpg (US) ... 21.9 km/L ... 4.6 L/100 km ... 62.0 mpg (Imp)


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  5. #24
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    Quote Originally Posted by theforerunner343 View Post
    You have to be in gear for DCFO to work. It keeps the engine running by the energy of the car rolling.
    Thanks! I'm just reporting what I see on my OBDII app and find it contradicts the expected DFCO fuel savings.

    Quote Originally Posted by theforerunner343 View Post
    If you shift into neutral, you're disengaging the engine from that free energy and the car then has to find some other energy to keep the engine turning, so it switches to idle and kicks the injectors back on.
    Of course. I've used DFCO quite a bit, and definitely notice the change in engine braking as I decelerate to around 1200 RPM.

    Quote Originally Posted by theforerunner343 View Post
    if you want movement with no fuel you either have to leave it in gear while coasting or turn the key to shut the engine off completely.
    Speck has no ignition key!




    Maybe this behavior has something to do with how the fuel consumption is either being reported or calculated, and I'm not sure how to verify it.

    Someone here put a meter to one of his injectors and reported that they do not get any electrical voltage during what they determined to be DFCO conditions.

    Good to know but it still doesn't explain the OBDII fuel consumption while coasting in neutral v. DFCO.

    In the end it's all good. I still get GREAT FUEL ECONOMY IN A CHEAP RELIABLE LITTLE CAR!!!!!


        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.0 mpg (US) ... 20.8 km/L ... 4.8 L/100 km ... 58.8 mpg (Imp)


  6. #25
    Moderator Eggman's Avatar
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    Quote Originally Posted by Eggman View Post
    Someone here put a meter to one of his injectors and reported that they do not get any electrical voltage during what they determined to be DFCO conditions.
    Found it. It was MightyMirageMpg: DFCO explained measured and how to utilize it

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.0 mpg (US) ... 20.8 km/L ... 4.8 L/100 km ... 58.8 mpg (Imp)


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    Quote Originally Posted by Eggman View Post
    Thanks! I'm just reporting what I see on my OBDII app and find it contradicts the expected DFCO fuel savings.

    Of course. I've used DFCO quite a bit, and definitely notice the change in engine braking as I decelerate to around 1200 RPM.
    Sorry, I guess I misunderstood your question. I thought you were asking why fuel is being used when in neutral.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage DE 1.2 automatic: 47.1 mpg (US) ... 20.0 km/L ... 5.0 L/100 km ... 56.6 mpg (Imp)


  8. #27
    Moderator Eggman's Avatar
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    Quote Originally Posted by theforerunner343 View Post
    Sorry, I guess I misunderstood your question. I thought you were asking why fuel is being used when in neutral.
    Yep! I understand that it's being used to keep the engine at idle speed but for some reason while coasting... - oh, never mind you know what I mean!

    And I apologize for any snarky undertones by using the dolphin gif it was more spur-of-the-moment humor than anything else. I thought some folks here would get a kick out of it.




        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.0 mpg (US) ... 20.8 km/L ... 4.8 L/100 km ... 58.8 mpg (Imp)


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