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Car wants to use engine only 90% of the time

Discussion in 'Prius c Main Forum' started by aquacorolla, Jul 18, 2024 at 2:45 AM.

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  1. aquacorolla

    aquacorolla New Member

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    Location:
    Australia
    Vehicle:
    Other Hybrid
    Model:
    N/A
    I felt this was the best place to ask because the issue concerns the drivetrain system which is identical to the Prius C. I will explain at the bottom. The car is 6-7 years old and had about 25000 miles when I bought it, I've added about 1000.

    Edited to add TLDR: Car uses hybrid system effectively in first 1-5 minutes after cold start, performance very good with motor, then car only uses engine unless very weak throttle, performance bad

    Problem:
    When I start the car for the first time in a day or after some time has passed, the car very eagerly uses the electric motor and acceleration is good even with light pedal presses. This is regardless of the hybrid battery level. When the battery is low, the engine just keeps running to charge it, but it doesn't affect performance.

    When I accelerate hard (but not WOT), the engine's RPMs do not increase, or increase less than 1000 rpm, and the acceleration response is instant like an electric car.

    However, after driving for about 1-5 minutes, the car shuts off the electric motor, except for a brief moment when accelerating from a stop, OR when the pedal is pressed very slightly, again regardless of the battery level. This is not enough to maintain typical speeds in my area (speed limits being 30 to 40 mph). Starting from traffic lights also makes the engine rev up to 2.5-3.5k if I want to keep pace and not piss off everyone behind me.

    When I have to accelerate hard, such as up hills, the engine spins up to about 3-5k yet it does not feel like I am going any faster which behaves exactly like our previous CVT petrol car.

    The power flow diagram in the dashboard display also only shows power flowing from the engine to the wheels and battery and no power from the motor. The only way I can get the motor to spin up is to go WOT which makes both the engine and motor work.

    I get between 45 to 60 mpg when I drive carelessly*. I can achieve 70 when I am trying to save fuel and drive like I am 70 years old. The other person who drives this car gets between 40 to 50. In the first state, my fuel consumption seems to be lower as the average goes down, but it happens too briefly for me to measure accurately.
    *Okay, by 'carelessly' I mean not being concerned with fuel economy. NOT driving without regard for road safety or other vehicles.

    Has anyone experienced something similar with their Prius C, and what could be the cause? This is something that would be very difficult to explain and prove to a mechanic or dealership. Is it just normal operation? I would have thought the electric motor would be activated a lot more. I can almost never use EV mode either as apparently I press the accelerator too hard just keeping up with slow city traffic.
    Thanks, from Australia

    Why I posted here:
    I believe it's safe to assume any experience and knowledge concerning the Prius C's hybrid system shared on this forum will also apply to my car. The car I drive (Japanese Corolla) is almost a Prius C as it shares exactly the same 1.5 hybrid drivetrain, battery and some chassis and suspension parts. Size and weight are almost the same. Even the hubcaps are the same. It is a Japan-only car, so there does not seem to be any dedicated forum, or it would have very little activity anyway.
     
    #1 aquacorolla, Jul 18, 2024 at 2:45 AM
    Last edited: Jul 18, 2024 at 2:53 AM
  2. BiomedO1

    BiomedO1 Senior Member

    Joined:
    Mar 27, 2021
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    Location:
    SacTown, Ca
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    I used to own a 2012 Prius C, but my understanding is that the EU/Japanese versions were programmed slightly differently from the US versions. Your version allows for battery only propulsion, ours always fire the ICE. The ICE only turns off when your coasting or going down hill.
    Prius C here in the states had a smaller traction battery than a standard Prius. The Corolla hybrid replaced the Prius C on this side of the pond. I think the Corolla also has a smaller battery than the regular Prius.

    FWIW: it sounds like your Prius C is operating normally. The car "learns" peoples driving style, so if one person likes to romp on the throttle and the other driver is gentle on the pedal. The car will assume a middle compromised position in it's programming. Though you may have some degradation in your traction battery pack. That's normal for a car of that age. When your battery pack drops to a certain level, it'll trigger a CEL Since you track your mileage, you'll know the traction pack is going bad long before it trips the CEL - your mileage will drop significantly and a lot more throttle response to get her going..

    Hope this helps....
     
    #2 BiomedO1, Jul 18, 2024 at 10:44 AM
    Last edited: Jul 18, 2024 at 10:57 AM
  3. ChapmanF

    ChapmanF Senior Member

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    Mar 30, 2008
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    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Assuming the drivetrain is, in fact, identical to the Prius c, what you've described cannot even happen. The electric motors (there are two) are never "shut off" when you are driving the car, as there is no way even for power from the engine to reach the wheels without participation of the motors. (The "Neutral" position on the gear shift is obtained exactly that way, by shutting off the motors.)

    So the car, in order to move, is always using the motors to some extent, and usually blending that in some proportion with use of the engine.

    What you have noticed at the 1 to 5 minute mark after startup aligns well with the engine reaching operating temperature. The car uses predominantly electric motor power while the engine is warming up, to reduce wear and tear on the cold engine. Once the engine is at operating temperature, the car favors using it for motive power.

    That last point is often not what new hybrid owners expect. But in a hybrid (that is not a plug-in), the only source of power is ultimately the gasoline, and the most efficient way to use it is to send power directly from the engine to the wheels. The hybrid is also capable of storing some energy in the battery when more is available than needed, and using it from the battery to supplement power for brief intervals. That is more efficient than simply losing the same energy as a non-hybrid would do, but it is not more efficient than simply getting the right amount of power from the engine to the wheels directly. So it ends up that the hybrid's behavior, for all the right reasons, is to operate as something very close to a gasoline-engine-powered car, very much of the time.
     
    #3 ChapmanF, Jul 18, 2024 at 11:22 AM
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