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Prius completely lost engine power *after* mountain pass

Discussion in 'Gen 2 Prius Technical Discussion' started by Celereycan, Oct 6, 2024 at 10:13 AM.

  1. Celereycan

    Celereycan Junior Member

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    I have a 2008 Prius with 203k miles and a refurbished hybrid battery installed at 190k miles 1.5 years ago. The vehicle works very well.

    Yesterday we drove over Sonora Pass in California (Route 108). Over a long stretch, you go from sea level to 9600 feet. The last stretch is quite steep. I did not take it particularly slowly and you can really hear the internal combustion engine run noisily. I've done this many times in California over various mountain passes.

    It was also an unusually hot day yesterday in the mountains. It was in the 80s at 7,000 feet and still in the 70s at the summit. I did not turn off the air conditioning. Perhaps I should have, but I've done done it in the Prius.

    Coming down the pass, we found ourselves at a relatively flat area around 7,500, and I started noticing the engine sputtering a little bit as we went over gentle uphills (there is still a little bit of uphill--up and down--even as you come down the mountain).

    Then, relatively suddenly and in a flat section, the car just lost forward propulsion. I was able to get to teh side of the road at about 1 mph. No check engine or other warning light came on.

    I turned off the vehicle and popped the hood, thinking perhaps the engine was overheating. There, of course, was no smoke, and there was no burning smell.

    A couple of minutes later, I started the vehicle up, turned off the a/c and drove gently to the next town (Bridgeport, CA). The car drove just fine. At a gas station I topped off the oil, adding 8/10 of a quart to get to teh top of the dots in the dipstick. (It had been about 2500 miles since the last oil change; I thought the car consumed more like 1 quart every 5,000 miles, but that's what I found.)

    We then drove rather gently for another 30 miles in 80-degree heat outside with no a/c before I turned the a/c on again. The car drove just fine.

    So here's my question: Could the car have overheated a bit over the pass and lost power for that reason (even though no engine light came on)? Or is it more likely that something else is wrong with the car, such that I should be worried that even taking the drive more gently coming home and without a/c that I won't make it? I'm traveling with ai 2-year-old....

    Thank you in advance for any advice! I should add that I did have the coolant control valve replaced several years ago. I also replaced the spark plugs at 145k miles. My engine air filter is pretty clean. I'm also using regular, conventional 5w30 oil, not "high-mileage" oil.
     
    #1 Celereycan, Oct 6, 2024 at 10:13 AM
  2. bisco

    bisco cookie crumbler

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    it might be that the refurb battery is weak and the engine was working too hard. i'm surprised you didn't get a trouble light though
     
    #2 bisco, Oct 6, 2024 at 2:12 PM
  3. PriusCamper

    PriusCamper Senior Member

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    Usually these symptoms happen with warning lights on the dash and those warming lights are stored as error codes so we can help you diagnose the problem. So... Did you have any warning lights? If you "lost all forward propulsion" it seems like you would?
     
    #3 PriusCamper, Oct 6, 2024 at 2:20 PM
  4. bisco

    bisco cookie crumbler

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    battery protection mode, maybe?
     
    #4 bisco, Oct 6, 2024 at 2:22 PM
  5. Celereycan

    Celereycan Junior Member

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    There were no warning lights, but I have a code reader, so I could look for codes.
     
    #5 Celereycan, Oct 6, 2024 at 6:22 PM
  6. dolj

    dolj Senior Member

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    Does your combination meter (the display that shows your speed, gear selection, and warning lights, among other things) work all the time or does it go dark from time to time?
     
    #6 dolj, Oct 6, 2024 at 10:40 PM
  7. Celereycan

    Celereycan Junior Member

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    I checked. No codes.
     
    #7 Celereycan, Oct 7, 2024 at 12:17 AM
  8. pasadena_commut

    pasadena_commut Senior Member

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    Refurbed batteries are not noted for longevity. If the OP has Dr. Prius or some other method of reading the pack voltages it would be a good idea to check them.

    That it failed after a long downhill suggests to me that the pack has problems accepting a large input current for a sustained period. One of the modules might have become very hot and the car shut down to protect it. When the car starts up do all the lights on the MFD come on? As others have noted, it is hard to see how this didn't trigger a code and it should have turned on a warning light. On really long downhill runs it is prudent to shift to "B" and turn on the lights, A/C, defroster, and radio so that once the pack is fully charged the excess current has someplace to go other than the pack. That is how I configure our Prius when descending from the Grapevine, for instance. Before the pack is fully charged having all that stuff on reduces the rate it which it charges, which is easier on the modules.

    Another possibility is that the pack fan is dirty and not moving enough air. That also could have resulted in the battery overheating when it was charging hard. If it has not been cleaned recently do so now.

    This is really a long shot, but check the engine air filter. The car might have sucked in a swarm of bugs or bunch of small leaves or something like that. The could have blocked enough of the air flow that the car gave up, and when it stopped that stuff redistributed enough that it could breath again.
     
    #8 pasadena_commut, Oct 7, 2024 at 2:45 PM
  9. BiomedO1

    BiomedO1 Senior Member

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    That's a steep, long climb. Mashing the pedal and whining out the engine isn't going to get you up that hill any faster. It's best to back-off and try to accelerate on the flats and short downhill sections to build up momentum for the next climb. Everybody is going to pass you and ride your bumper. Most likely your traction battery overheated. Make sure your traction battery fans are working and your cooling vents are clear. If your doing this trip a lot, install an engine coolant temperature gauge - so you don't blow up your motor.

    Just my 2-cents..

    If your going to keep this car; I'd install a new traction pack.
     
    #9 BiomedO1, Oct 7, 2024 at 4:43 PM
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