2009 Prius - Trouble in mountain driving?

The Prius is not a hill climbing brute, but we feel find it a worthy road tripping car for us and our two kids. Ofttimes it's needed to turn off the A/C and fan to ascend hills well. And listen to how the car is winding up and drop speed a bit to keep it feeling like it is operating in the right range. But it's not like you have to do a granny crawl to get up the hills with it.

A couple weeks ago we drove 2200 miles between Utah, the Sierra Nevadas, Yosemite, and finally San Francisco. 200 miles one day around Yosemite we averaged just shy of 47mpg even with nearly 5000' ascents -- because there were also impressive descents and a continuous flow of traffic, not a bunch of starting and stopping. Around San Francisco we only averaged around 40mpg because, I think, of the many stops and starts on all the hills.

Going from Sacramento up over Donners Pass we were only going about 45-50 mph up the big climbs. MPG looked as bad as mid-30s at times with a fully purple battery showing. But of course you get rewarded with great mileage and comfortable speeds on more level and descending terrain. The battery seems to pretty quickly recharge.

At any rate, over the course of this road trip with lots of climbs and descents we averaged about 44mpg, and I feel that was an incredible bargain considering the terrain and that we drove a lot of freeway miles at 85mph, which is definitely not the most efficient freeway speed for the Prius.

 

My Prius does fine on the upgrades. The engine does wind up pretty good, lots of noise but always willing. Generally just put your foot down. I think as a matter of engineering Toyota made the throttle in the Prius a little stiffer than it would be in a performance model as a way to improve milage.

That said, if you are pushing the pedal all the way down and the car isn't giving you reasonable performance something isn't right. I wonder if the battery might be too hot. Did the car sit in the sun in Bisby? If it did I bet it got plenty warm. I would NOT turn off the AC in Arizona in August. The battery performs better when it's cool, and so do you.

 

I had the same thing happen to me going to Colorado Springs. Got lousy mileage and had the depleted battery. I was climbing quite a way. Got to Colorado Springs & had the local Toyota dealer check it out and they found nothing. Battery and mileage came back to normal while there. I agree with quixotequest that this isn't a hill climbing brute. P.S. haven't had a problem since now I know LONG hills are a battery & mileage killer.

 

This is totally normal for the second-gen. Look at some of the
tags that Priuschat tacked onto this very thread, and chase
some of the links for more mountain-driving discussion. My big
roadtrip report from last year included a bunch of similar
observations too. Don't worry about it, drop in behind that
truck crawling up the slope with its flashers on and keep your
RPM around 3000 if you want to still do it efficiently, and
enjoy the scenery.
.
_H*

 

Don't be afraid to use more gas pedal, including keeping it floored. The engine will roar but that is completely normal; the computers will not allow it to harm itself.

 

Interestingly I was at Yosemite a few days ago. While I didn't experience your trouble, I had an interesting even on the consumption screen on the way out of Yosemite descending.
I had two segments at 100MPG and 2.5 car regen. I was looking for the 3rd segment but noticed only the 2.5 car regen and no green.
Initial reaction, there goes the green segment
Finally the next segment showed 100MPG and the black segment moved on and on to the end I am pretty sure I didn't get stuck in traffic on the way down to not show anything green. What is curious is that it did show 2.5 cars of regen in that black segment. How could this be?

 

"Second trip this past weekend in southern AZ - strangely I had a fully green recharge on a short decline into Bisbee (5500') after doing ok during the ascent in. Parked for two hours and started the ascent out. Fully charged green battery, full tank of gas - and the car hesitated every time I accelerated. I was going about 20mph, cars lined up behind me because the car would NOT accelerate... just kept hesitating and felt like it was going to stall? I parked for about 10 minutes, shut the car off, and tried again -- did better and stopped hesitating."



Yes, I have had that problem. Had it pushed to the floor and it would NOT move, I had almost green for the battery, and half a tank of gas. Stopped after 10, sometimes longer, minutes. But one think I did notice is that when this has happened (about 3 times) is I had the AC on..but I don't know if that affected anything. Hope this helps.

 

I'm familiar with the areas that you described above and have driven there with my 2004. It is not normal for your car to behave the way that you describe. However if you don't have any warning lights on, then it will probably be tough for your dealer to take any action.

In May 2009 my 2004 behaved similarly as your car with regards to hesitation, etc. However warning lights did appear. Precision Toyota in Tucson downloaded current firmware into the engine and hybrid vehicle ECUs. No recurrence of the driveability issue since then, and the car has logged 10K more miles including a 3,700 mile trip last week from AZ to SD to southern CA and back to AZ.

Putting your gear selector into B will not help the traction battery to recharge. Instead, some of the regen energy is being used to spin the gasoline engine at a higher RPM (the equivalent of shifting into low gear with a normal car.)

 

Yes, B just throws away energy.

The depleted battery and racing engine is normal on a steep climb, particularly with the A/C on. Other than getting lower MPG, there's no harm done. I've done the Phoenix-Flagstaff run many times.

I'm a little concerned with the full battery yet hesitation. I haven't seen that. Was the car cabin very hot? Is the vent for the battery in the back seat clear? If the battery is hot, the performance will be reduced.

 

I am happy to report that the Gen3 Prius has none of the above described problems. Today, I drove to Park City, UT and back. Heavy mountainous driving ... no problem. I maintained 70 mph the entire trip, and recorded 54 mpg (obviously not that high going up, but we more than made up for it coming down) in doing so.

Several weeks ago we drove to Yellowstone NP, and drove up and down a long 10% grade between Driggs, ID and Jackson Village, WY.. It was one of the few times I have heard the engine, but it was not protesting.

I am absolutely delighted with the power and performance of the G3.

 

Based on some rules of thumb I use for fuel planning, 18 mpg is what I expect from my Prius while climbing a 7% slope at highway speed. Climbing consumes a considerable amount of fuel just to lift all that mass. With a car as efficient as Prius, consuming very little fuel on the flats, the climbing effect becomes especially noticeable. The descent should use no fuel, and fill the traction battery.

My Subaru would get about 13-14 mpg on that climb, compared to 27-30 mpg on the flats. It also uses no fuel on the descent, but has no battery to fill up.

The hesitation problems are not familiar in my very short Prius experience. To echo a previous reply, make sure the right rear seat passenger or cargo does not block the vent to the battery, and don't be afraid to nearly floor the gas.

 

Quick off-topic but related question, can you shift into B mode while in motion, i.e. during the descent.

 

Yes. This is how it is intended to be used.

Tom

 

The battery is good for a theoretical maximum of about 600 vertical
feet of regen if you start from the lowest permissible SOC, that's
it. In real life you get less than that.
.
The 2010 has a barometric sensor in the inverter, which helps it deal
with various altitude-related issues. Toyota learned.
.
_H*

 

Hobbit (anyone else),

Do you know if Toyota made a software change in how the power is distributed between the 2006 and 2007 model years?

The reason I ask is I drove my wife's 2007 touring to meet Wayne to have an EBH installed in Beckely, WV over the weekend, THANKS AGAIN!!!, and her car behaved quite differently from mine going up the 7 mile hill at the NC/VA border.

I set the cruise on my 2006 and go up this hill at 68 MPH and when I reach the top my 5 minute consumption screen shows about 25 MPG for the climb, sometimes a little more sometimes a little less depending. The critical thing is my SOC is at 5 bars at least and usually 6.

On Sunday I took her car up the same hill set at the same 68 MPH and when I reached the top my 5 minute consumption screen was again at about 25 MPG, HOWEVER the SOC was only at 3 bars? I never see it that low in my car when I climb that hill.

I also watched the Energy screen during the climb and am used to seeing my car almost "pulse" the battery to electric motor to wheels arrows to assist the ICE when climbing. Then it would "pulse" for a couple seconds back from ICE to electric motor to battery and alternate this back and forth up the hill. This is very typical for my 2006 when climbing hills at highway speeds.

Her 2007 behaved much differently. It had a substantially longer period of battery to electric motor to wheels to assist the ICE when climbing. It almost never "pulsed" in the opposite direction until the SOC reached 2 bars (purple) then it seemed to pulse between 2 (purple) and 3 (blue) bars?!?!?

The only thing that I could think of that would cause this was a software change? I don't see any fundamental differences in the vehicles that would cause it. Yeah the touring has bigger tires and different suspension but why would this affect the power management system?

Another thing that got me thinking about this was while Wayne and I were having lunch after my EBH install he mentioned his 2010 seemed to go to a lower SOC than his 2005 when climbing hills. I see low SOC during hill climbs at low speeds (under 50 or so?) in my car but never see it during hill climbs at highway speeds. Yes the ICE revs its little heart out to get you up the hill but my SOC has never gone below 4 bars, that I can remember.

Anyway, my wife's car, conversation with Wayne and how my car reacts to hills got me thinking about all this "Hill Climb/SOC Stuff" so I thought I would ask.

Any ideas?

Chris

 

This thread is making me nervous. I have a trip up to the White Mountains at the end of this month, Kangamangus area.

 

Don't worry overmuch. If it is working properly it will have no trouble.

Arizonaprius, do you have an update? Was there a fault in the car, or was it operator error ? :_>

 

I've driven through a 12,000 foot pass with our 2006 without trouble. Don't expect to set any speed records, but you will do as well as the normal cars.

Tom

 

Xmas 2008 in my 2008 Prius, I was driving on I-40 in east TN. There was an ice storm and I could not get up the mountains. I was in the right lane with the big trucks. I want to get rid of my OEM tires but with 15,000 miles they still have lots of tread. Just hope I don't drive in any more ice storms.