08 Revving more than it used to uphill

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by TheDrGene, Sep 29, 2012.

  1. TheDrGene

    TheDrGene Beard and Sandals Group

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    My wife and i have noticed over the last few months that our 08 has been revving higher, (much higher), than it used to when driving uphill. Any thoughts or suggestions. It has 65 k miles.
     
  2. PriusCamper

    PriusCamper Senior Member

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    Have you noticed a change in MPG?

    If not, I'd say it has to do with something happening to the car that made you notice the noise more... Maybe you lost an underbody panel or some sound dampening material has come loose?
     
  3. nh7o

    nh7o Off grid since 1980

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    1. As always, check the 12V battery. If it has a shorted cell, it will draw continuous charging power that just goes into heat.

    2. How's the HV battery? Sudden fluctuations from high to low in the SOC display? Is the battery cooling fan running audibly?

    3. The engine may be putting out less, and is revving higher to compensate. Throttle body clean? How are the MPG's ?

    This symptom is seen here often enough. Spending a little on an OBDII port/USB interface that allows to run a free program like Priidash on a laptop can help sort this sort of thing out.
     
  4. TheDrGene

    TheDrGene Beard and Sandals Group

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    MPG has been down by 5-6 mpg, but we have been blaming that on a change in a set of tires. (Went from Michelin Radial X to Bridgestone Ecopia). As far as noise, last year I put a Dynamat type material in all the doors, hatch, basically anywhere I could and the road noise is much less. Its not that we are hearing more road noise, the engine is distinctly revving higher on uphills.

    We have not been hearing a fan for cooling the HV battery, (though other than the battery display on the MFD, I do not know how to evaluate the battery). How would I evaluate the HV battery?

    I have not cleaned the throttle body, though I have run fuel injector cleaner with a tank of fuel a few months ago. (I know, I know, the throttle body has nothing to do with clean injectors). The air filter looks good and I replaced it with the last oil change.

    I appreciate the suggestions
    Thanks
    Gene
     
  5. uart

    uart Senior Member

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    Normally you'd expect the MPG to be a little better with the Ecopias.

    Have you noticed any anomalies in the state of charge (SOC). It is fairly normal to hear the engine working harder to accelerate or climb hills when the SOC is low. If your SOC is suddenly much lower or more varied than before then obviously it could be a problem with the traction battery getting weaker.

    If the SOC is behaving normally then it could be a problem with the HV battery cooling. Even if the SOC is good, it won't contribute electric power properly if the battery is too hot. Take it for a decent drive in warm weather and then while in ready (and with engine off so you can hear everything well) place your ear near the vent at the back seat and listen for the fan. If you've driven in warm weather you should hear it running fairly quietly. If you don't hear it at all then there might be a problem with the fan not turning. If you hear it really loudly then the battery is probably getting too hot (could be obstructed fan/vents, or it could be a failing battery).

    Thirdly, I think that you might get similar symptoms if the inverter gets too hot, so definitely check the reservoir (near the inverter, in ready mode) and make sure you are getting good coolant flow.
     
  6. nh7o

    nh7o Off grid since 1980

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    +1 on checking for inverter coolant flow.

    The ICE works with MG1/MG2 to drive the wheels. If the electric portion of the system is overheating somewhere, then the torque from MG1/MG2 is reduced as a protective measure, and the engine works harder to compensate. It appears that the improved pumps in the later GenII's are not much better than the previous failure prone version, and there are reports here of replacement pumps failing as well.

    But your miles are low so pump failure would be surprising, though not impossible.
     
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