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Why distance to empty fluctuates

Discussion in 'Engine Compartment' started by sageeshr, Jan 29, 2015.

  1. sageeshr

    sageeshr Amatore

    Messages:
    75
    Bangalore
    Sarjapur Road
    Grande Punto 1.3 90 HP
    Could any one please tell me why there is a high variation in 'distance to empty' in short duration? I find a huge difference in it,say approx 125km - 88km in short span of running. Is it as expected or a problem?
  2. Ravi

    Ravi Staff Member Janitor

    Messages:
    6,001
    Bangalore
    Grande Punto 1.3
    What was the short span, KMs? And how was traffic on those short span?
    This gets adjusted based on your current driving conditions and fuel available.
  3. sageeshr

    sageeshr Amatore

    Messages:
    75
    Bangalore
    Sarjapur Road
    Grande Punto 1.3 90 HP
    It was 112Km to empty when I have started it in this morning,it became 88Km after running for 4-5 Kms.Later it went back to 122Km when I have parked the car after covering 17-18 Kms(Total).
  4. pabhishek

    pabhishek Esperto

    Messages:
    1,382
    Oslo
    Pune
    Linea T-Jet
    As Ravi said, it depends on traffic and your driving style during that trip @sageeshr

    When your DTE gets lowered for the first few kms, most probably you will be in lower gears for most of the time. For eg 2000rpm in 2nd gear.

    When it returned back to what it was earlier, may be the traffic was less and your car was in 4th-5th gear for most of the time. For eg 1800- 2000 rpm in 4th gear.
  5. ghodlur

    ghodlur Esperto

    Messages:
    2,325
    Thane
    DTE displays the estimated distance and is only indicative readings. A lot depends on the displayed reading such as fuel level, speed, gear changes. Even frequent braking also affects the DTE readings. The ECU keeps scanning continuously for all the required parameters and based on an algorithm calculates and displays the estimated distance that can be covered. Once stable the values will be different than at the start of the journey.

    Now coming to your question why does the DTE fluctuate - try a simple experiment. Hold a 1 ltr bottle filled with water (not fully) and start walking keeping the bottle at horizontal position. Try to gauge the water level in the bottle. At one point you will try to average the water level since the level keeps fluctuating based on your speed, the way you hold the bottle and lot other parameters. Now try to equate this experiment to DTE display in your car. You will get your answers.

    Attaching a file which answers most of the DTE FAQ's which I had got from Ford for my Fiesta when i used to get rattled by the ever swinging DTE values.

    Attached Files:

    asimpleson, mchanna and Mabams1826 like this.
  6. RaviHegde

    RaviHegde Regolare

    Messages:
    299
    Karnataka
    14.62°N 74.85°E
    Grande Punto 1.4
    Another reason is - engine is not most efficient when you cold start it. Its efficiency goes up after it heats up to the operating temperature. Therefore initially mileage is lower ending up in lower DTE number. But very quickly (within few kms) engine heats up and the DTE number jumps up.
    mchanna likes this.
  7. sageeshr

    sageeshr Amatore

    Messages:
    75
    Bangalore
    Sarjapur Road
    Grande Punto 1.3 90 HP
    Thanks friends for sharing the details and clearing the doubts.Its really a great support here.

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