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Thread: EPS (electric power steering) actively self-centers steering for 2017 (video)

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    Administrator MetroMPG's Avatar
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    EPS (electric power steering) actively self-centers steering for 2017 (video)

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    [Admin note -- this topic split off from thread: Darin's test drive review notes: 2017 Mitsubishi Mirage G4 sedan CVT ]

    The steering feel and self-centering in the 2017 Mirage is much improved, as seen when comparing strawboss' 2015 Mirage hatchback against the 2017 Mirage G4 sedan.

    When I started driving the car around town, I suspected that the changes were in the EPS (electric power steering), not in the physical steering setup.

    I confirmed it with a little test to see how the car's steering centers at low speed with no driver input:

    Test #1: EPS disabled

    1) Turn the steering 90 degrees with the car stationary, in an empty parking lot.
    2) Let off brake and accelerate VERY gently up to 25 km/h (15 mph).
    3) Watch how far the steering wheel returns towards center on its own (no driver input) .

    Test #2: with EPS enabled

    1 - 3) Repeat steps 1-3, above.

    Here's what happened.

    Steering wheel starting position, car stopped:

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    Result of Test #1) EPS disabled, steering wheel end position @ 25 km/h:

    The steering gradually unwinds to around 1/8 of a turn, then stays there even as speed continues to increase.

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    Result of Test #2) EPS enabled, steering wheel end position @ 25 km/h:

    The steering gradually unwinds at first (like with EPS off) as the car starts to move, then unwinds more quickly to near center.

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    What I noticed is that with the EPS enabled, it actively un-winds / straightens (almost) the steering when the car passes roughly 10 km/h (6 mph).

    It's something I suspected it was doing, because sometimes it felt like the self-centering wasn't linear. At certain speeds, and at certain steering angles, when you're letting the steering wheel slide through your hands after a turn you may feel it unwind slightly more quickly/forcefully at a certain point.

    I even made a short video. Active self-centering happens at around the 6 second mark:




        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage base ES 1.2 manual: 54.0 mpg (US) ... 23.0 km/L ... 4.4 L/100 km ... 64.9 mpg (Imp)


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    Daox (10-13-2016),Eggman (10-13-2016),MysticMirage (10-14-2016),Top_Fuel (10-13-2016)

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        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage base ES 1.2 manual: 54.0 mpg (US) ... 23.0 km/L ... 4.4 L/100 km ... 64.9 mpg (Imp)


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    Great test! Great news! Now the next step is to find out how to get this programming on our 2014/2015 cars.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE 1.2 automatic: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.8 mpg (Imp)


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    I sometimes wish for the efficiency and simplicity of manual steering.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 48.8 mpg (US) ... 20.7 km/L ... 4.8 L/100 km ... 58.6 mpg (Imp)


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    I'd rather convert it to full manual as well.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage DE 1.2 manual: 49.2 mpg (US) ... 20.9 km/L ... 4.8 L/100 km ... 59.1 mpg (Imp)


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    Hah, that is so weird. Not a horrible idea for Mitsu though. Seems they are listening to customers when redesigning things.

        __________________________________________

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


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    Administrator MetroMPG's Avatar
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    Quote Originally Posted by Eggman View Post
    I sometimes wish for the efficiency and simplicity of manual steering.
    If it were a hydraulic system, I could see the case for it -- much more parasitic losses.

    But I bet the efficiency impact of the electric system is negligible.

    Still, if you really wanted manual steering, you could DIY it - just remove the e-motor.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage base ES 1.2 manual: 54.0 mpg (US) ... 23.0 km/L ... 4.4 L/100 km ... 64.9 mpg (Imp)


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    The real problem about the numb and sticky steering with practically zero feedback is, there is much to high permitted torque in the pieces of the system. The torque needed to move the ball joints, the steering box, the worm gear, that all adds up to such ridiculously torque, its like having a brake hindering normal movement of the steering wheel.

    My other car when jacked up with power assist off, needs less than one fifth of the effort to turn the wheel than my Mirage when I got it! Now my Mirage has since been fitted with normal-quality after market ball joints and had the steering box friction-reduced, which has helped very much, although the steering still remains quite inferior in comparison to similar cars.

    If that imposition doesn't get corrected, for example by using better quality made ball joints and a steering box with very much lower internal friction, you could do nothing else than mess with the electronics in an attempt to hide the symptoms from the cheapo parts that the Mirage's steering system is made of, however that way, the issue of low or zero feedback will remain. You just can't get away ignoring the laws of physics.
    Last edited by foama; 10-15-2016 at 07:43 PM.

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    Quote Originally Posted by MetroMPG View Post
    Still, if you really wanted manual steering, you could DIY it - just remove the e-motor.
    Considering how modifications impact how the manufacturer and dealer service the car, and the impact upon insurance, I would rather the manual steering come from the factory. I can easily see how I would be automatically at fault in any accident due to disabling the power steering. At the same time, I can see how manual steering would be a liability for the manufacturer.

    The times they are a changing.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 48.8 mpg (US) ... 20.7 km/L ... 4.8 L/100 km ... 58.6 mpg (Imp)


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    2017 hatchback does it too

    I got a chance to drive a base 2017 hatchback this weekend, and can confirm it does the same active self-centering of the steering at low speeds.


        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage base ES 1.2 manual: 54.0 mpg (US) ... 23.0 km/L ... 4.4 L/100 km ... 64.9 mpg (Imp)


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