1. pasadena_commut

    pasadena_commut Senior Member

    Joined:
    May 2, 2019
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    Location:
    Southern California
    Vehicle:
    2007 Prius
    Model:
    N/A
    It feels like our 2007 is warming up slower, often taking an extra 5 minutes or so before the MPG bars show best efficiency. Which is unexpected because it has been quite warm lately, often near 90F, and naively one would expect that to result in faster ICE warm ups. So maybe not an ICE warm up issue.

    I may be hallucinating about this, and it could represent something environmental, like changes in driving patterns. There has been a lot of stop and go with the A/C on, for instance. But for the sake of argument, if there was a problem, what should I look for in Techstream? Coolant temperature, pack temperature, something VVT related? No CEL is lit.

    Thinking about the pack temperature as a possibility because the car is parked in the sun, and it might take a long time for the A/C and pack fan to cool the preheated pack down to a temperature where it works better. The other day I looked at that with Torque and pack T2 was 105F at the moment the car turned on and then with A/C on it quickly went to 107-108, it had not come down much in a couple of minutes sitting in the driveway. Better cooling when moving than sitting still, of course.

    Edit: just checked again with Torque and no error codes. It is earlier in the day and battery T2 at startup was 87 which is only a little more than ambient of 85. Windows in car have been open since the sun came up, last time it was early afternoon and the windows had been closed.
     
    #1 pasadena_commut, Jul 9, 2025 at 2:24 PM
    Last edited: Jul 9, 2025 at 2:36 PM
  2. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
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    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    Your High Voltage battery provides lots of energy to the AC system and in super hot weather the computer will send less High Voltage power for AC use so the battery drains slower.

    But that doesn't explain what you're correct in calling a hallucination because you're using MPG bars to diagnose engine warmup temp and those mpg bars are an approximation of lots of different factors. For example, just a little less air in one of your tires could change that measure of efficiency.

    If you want to watch your engine coolant temp or pack temp buy an OBD2 bluetooth reader to connect your car to your phone so you can run apps that will give you that data.