2017 Prius Prime Premium - Power and Smell issues

Discussion in 'Prime Technical Discussion' started by JTEM, Feb 4, 2019.

  1. JTEM

    JTEM Member

    Oct 9, 2017
    Boston, MA
    2017 Prius Prime
    Prime Premium
    I have been noticing the following in the last few thousand miles:
    1. In hybrid mode, the car engine seems much noisier than before. Also feels like the engine has to go to a higher rev to keep up with traffic.
    2. When going up long hills, I start getting a funny smell that is a mix of sulphur dioxide and something else, while the engine is laboring to get uphill.
    I don't experience this when I am in the EV mode.

    Anybody else experience anything similar? Perhaps this is the result of colder weather? Or maybe I am falling out of love with the Prius Prime.....



    2017 Prius Prime, Premium trim
  2. schja01

    schja01 One of very few in Chicagoland

    Apr 22, 2005
    2018 Prius
    Prime Advanced
    Compared to my Gen 2 Prius I think the engine is louder after the initial start of the day but quiets down in a few minutes.
    I think higher revs are a nature of the beast in that my Prime, previous Gen 2 and friends Gen 4 all do/did it.
    On a related aside I had a Camry Hybrid the first year they came out (06?) and a Camry V6 of the same year. The hybrid really strained on hills the V6 did not. Probably an apples to oranges comparison but thought I’d mention it.
    I’ve noticed a sulphuric odor near the exhaust if the engine hasn’t reached operating temp. Noticeable but not in the cabin only outside.
  3. m8547

    m8547 Active Member

    Aug 8, 2018
    2018 Prius Prime
    Prime Plus
    Sulfur smell is also common if you get the exhaust system hotter than average, for example after hard acceleration. It might or might not indicate a problem with the catalytic converters. I think for the 4runner some people have successfully gotten Toyota to replace their catalytic converters, but the consensus seems to be that it's not a big deal, and probably normal as long as you don't get a check engine light. The emissions systems in a Prius are probably a lot more sophisticated than an old 4runner, so no way to know what's normal.

    It seems like there's a fine line between not really hearing the engine at all, and the engine revving relatively high. In my experience, most of the time you're in the PWR range on the display the engine will rev high. And then once the engine is at high RPMs, there's not much more power available. If you put your foot down you can feel the electric motor help out, but even that is not too powerful at highway speeds. But there should always be enough power that you can still accelerate going up any reasonable hill. One of the more difficult hills for cars around here is a 5-6% grade, 60mph speed limit, at 11,000 feet. The altitude reduces the engine power by about 33%. I tested mine there, and I can still accelerate up to 70 in a reasonable amount of time if I floor it (in HV mode. Probably fine in EV mode too, but I don't usually have any charge left at that point, or if I do I'm saving it for later). And another steep one I tested is a 10% grade at 45mph at around 7,000 feet. I can accelerate there too.

    What you describe could possibly be symptoms of a problem. If the engine is running rich for some reason it would have less power, and the extra unburned fuel will make the catalytic converters work harder. It might run rich if you have bad gas, like if the octane is too low and it's trying to prevent knocking. Or maybe other reasons, but it's computer controlled, not adjustable (that I know of), and if there's no check engine light it's probably not too big of a problem. Another symptom would be if your gas mileage is lower than it should be. But it might be hard to know what it should be if it's really cold outside.
  4. FuelMiser

    FuelMiser Senior Member

    Jun 29, 2008
    Monument, CO
    2016 Prius
    1. I wouldn't worry about the sulfur smell, per se, but I wonder if you mean to say you get this smell in the cabin while driving? That would worry me, because it should only be coming out the tailpipe, which should not enter the cabin while driving.
    2. As for the engine noise, as long as you are using the recommended grade of engine oil, 0W-20, you monitor the level and you change on schedule, I wouldn't worry about it. The 4th gen ICE will make a noticeable "droning" sound under load normally.