OK so this has happened to me four times and here is the scenario: Plugged in for full charge Drive on freeway, HV battery depletes after 28 miles and I can feel ICE kick in when EV mileage goes to 0.0 Keep driving approx. 65-70 MPH and after maybe 2 miles on ICE I feel car slowing down I feel this so I push pedal down a little to get back up to speed MPH keeps decreasing, now down to 55-60 from 65-70 Push pedal all they way to floor and see power bar in middle of dash go clear over to full red "Power" Still slowing down ZERO check engine light or any warnings going off on the information display Let up pedal and fully depress again moving indicator bar back to "Power" red again Still slowing down, now down to 45 Rapidly depress the pedal 3, 4, 5 8 times and do not feel engine kicking in Finally i feel engine kick in and MPH increasing even with pedal only halfway depressed At a loss for why this is happening. Seems to be on the freeways, HV battery was fully charged then drove the 28 or so miles until is is out on the meter and initially the ICE engine kicks in but then for some reason it stops running?? I just had it at the dealer and explained this. The checked 12V battery (No issue), HV Traction Battery (no issue), no engine codes set. The web had confusing info on which battery actually starts the ICE, one said the 12V one said the HV battery. The dealers master mechanic said it is the HV battery that actually starts the engine but the 12V gives the power to the onboard computer systems that control everything. So he said a bad 12V would not let the engine start but you would also lose lights and dash instrumentation which none of that has happened. Dealer is at a loss on what to do next. I told him I would monitor it more closely to see what the variables are. Any of you experience this or have thoughts. I love this car but with a 18 YO daughter that drives it everywhere I don't want her to be stranded or have an accident because no throttle at highway speeds
he is correct about starting the engine, but once the car is ready, the inverter takes over for the 12v and also keeps it charged, so it does not come into play when driving. without any trouble lights, it's a tough one. how many miles on her?
I would question the dealerships' master mechanic knowledge on these cars; either that or you misunderstood him. @bisco is correct; once the car is in ready mode; the DC-DC convert takes over and the 12V battery does nothing but recharge. So unless you lose instrumentation power; that's not the issue. Is this happening all the time or just once in a blue moon? When the car slows down, what's the ICE doing; is it red-lined or even ON? To troubleshoot, you'll need to isolate the issue to either the transmission or the engine system. Does your battery indicator empty out, when this happens? I've never seen mine empty out. There's always an eight inch sliver on the bottom, even when I'm rifling though the mountains. My car always maintains the bottom quarter on the battery indicator while I'm in HV mode and not demanding power all the time. On the flats, running around town. You may have an intermittent, partially clogged fuel pump - if the engine is running and you can't accelerate; fuel starvation or bad gas. It can't be the gas pedal, because it doesn't do it while in EV mode - the ECU is using the same data input point. Does that car have a branded title?
i wonder if a battery with an intermittent internal short could cause it without throwing a code, or loose battery connections
An intermittent short could wack out the ECU, but I doubt a loose battery connection would effect the car while in motion. The DC-DC converter has taken over; but good theory...... Come to think of it; a bad or intermittent ground cable to the engine itself could prevent or cause intermittent ignition, no spark.
When driving in EV, is the engine cold? Didn't it start during the trip? Then it needs to warm up and reach operating temperatures. If a cold engine starts giving up its power at 100 mph, it will quickly leave this world. To help, the high-voltage battery is activated.
@MAX2 , the engine was not cold per se but I had driven 28 miles on EV and then motor initially kicked in but then stopped
@BiomedO1 , never lost any instrumentation as it was night time and all was functioning properly. It happens very intermittently, four times over the past six months. I do have the sliver on HV battery monitor and when I press the pedal I can get the throttle indicator on the dash to redline but motor is not running as I can not hear it nor feel vibrations or hear it revving up. I don't believe I have a fuel pump or filter issue as I do fill with gas at least once a month. Car has 65K mile on her
That's correct; when the ICE kicks on at highway speeds - it takes a few seconds to begin contributing to overall power and performance of the car. I've never had mine slow from 70 mph down to 40 mph traveling down the highway and there should be enough left in the traction battery to see you through the transition. That would explain why pumping the gas pedal did nothing; but there has to be some exaggeration in there too. Again, that transition window is only a few seconds long. Whenever I get on the highway and up to speed; I manually kick my car into HV mode to avoid those kind of surprises. The gas pedal gets pretty mushy for a bit; while transitioning. I like to chose where that happens in my journey - I don't want any surprises; if I need to do some "creative driving".
My 2019 Prime seems to have more power under the EV mode than running under the ICE. Not so much on the highway, but around town, definitely. It's like it loses a lot of power when the EV range expires. Almost like you need to start looking for a place to pull over. It still drives though. The ICE engine is started using the HV battery using the same motor that powers the car under EV. When I got my Gen 3 (not a prime), it had a bad 02 sensor. Not that it's usually the problem but I did have a couple times when the ICE didn't start in the morning (or ran rough for a bit) until I changed the sensor. Other than that, the ICE has never had a problem starting in any of the 3 Prii I've owned. The 12V auxiliary battery powers most of the other systems in your car. Every computer, the steering, the power brake booster. You'd definitely know if that battery isn't working. There's gotta be some codes (misfires, whatever) when your car has the problem. Maybe they're reading the generic codes and not the vehicle specific ones?
He allegedly took it to the dealership, see my comment in #3. Even if the car's ECU screen shows that the traction battery is completely "flat", no bars, there's a hidden reserve left; good for several engine startup attempts. But your correct, there should be codes or at least pending codes if something violated parameters. YMMV
Do you use diagnostic tools to measure engine temperature? What temperatures did it have before EV mode was engaged?
