Gas engine turning on & off rapidly in rush hour traffic with hot weather and AC running

Sounds like a good reason to install the EV button mod.

Dave

 

Are you drifting along steadily at the average speed of traffic, or
doing a bunch of go/stop and closing all the gaps too quickly? Try
letting a nice long gap open in front of you while just letting the
"creep" pull the car forward slowly, and wait till you get enough
space for a "good burn" and actually use the engine for real. But
just enough to start slowly closing the gap, not to close it quickly
and then have to cram on the brakes behind the next car. The less
you have to use the brakes the better, even in traffic like that,
and if you think about the dynamics a little, and the average speed
that everyone is making [regardless of individual behavior], you can
map that into more efficient engine use. Yes, the SoC will float
down around two or three bars under those conditions -- that's
normal, and the side effect is that very light demand starts the
ICE for propulsion.
.
And if you're about to counterargue "...but everyone will jump into
the gap if I leave one!", read this first.
.
_H*

 

<div class='quotetop'>QUOTE(Wetnabber @ Apr 28 2007, 02:33 PM) [snapback]431824[/snapback]</div>

Now that's what I call South Texas! BTW, how did you get a package #9 on a 2006 Prius?

Back on topic, where are you located? I was just driving in stop and go traffic yesterday from Culebra west of Loop 1604 all the way to 35 North of 1604 (long drive) and it was HEAVY traffic all the way. As luck has it, there was even an accident right in front of my neighborhood so I couldn't even get home. Anyway, I also experienced what you mention in my 2006 pkg #8. Culebra is a single lane road with a few traffic lights and you better believe that traffic was literally crawling. Surprisingly, I was able to go about 2 miles all the way to 1604 in traffic without the ICE starting at all. Of course I was being very conservative, I seem to remember the outside temp showing around 78* so I had the A/C off, vents off, radio off and I even turned the MFD screen off and rolled all 4 windows down to about eye level and I was actually quite comfortable with the slight breeze (fortunately it's not blazing hot yet her in S.A.). But once again, I did about 2 miles in traffic electric only and had no problems and the battery SOC was still reading just below 1/2 on the MFD (carefull technique of waiting a few seconds as the cars ahead of me pull forward then I gradually accelerate to stay in stealth mode and quickly let off to let it coast and charge until I reach the stopped car ahead of me again, you have to time it just right and predict the stop and go). The onramp to 1604 was empty so the ICE took me up the ramp but I had to merge with completely stopped traffic, this is where the similar condition began. As the charge slowly dropped while I was climbing a moderate hill I did start to notice the same pattern even as I came over the hill that it was extremely difficult to move at all without the ICE coming on, but like other said it's completely normal and I pretty much ignored it and let it happen. Like others also suggested, maybe placing the shifter in the "B" position to keep the ICE running would help in your situation, or perhaps the engine braking could be even more annoying than the stop/start. Anyway, eventually the traffic started moving around I-10 at moderate speeds which the ICE was required (and I was able to roll up the windows and turn on the A/C) and I still averaged over 52 MPG. You'll just have to try different techniques to see what works best for you, if you can't find a better solution then let me know when you're ready to sell the Prius (I might know some people who would like one). Oh, I've also had a Honda Insight, believe me, the Prius is way better than Honda's hybrids IMO but I do miss the 65 MPG I used to get sweltering in the Insight.

edit: Perhaps the reason for the continuous stop/start cycling could be due to the battery pack temperatures from extensive use and Texas heat, it could be reaching high temps and every time you touch the accelerater with even the slightest demand it causes too much heat forcing the ICE to take over. Of course it's hard to be sure unless you have a can-view or something, but I suppose it may be possible.

 

<div class='quotetop'>QUOTE(nark @ Apr 28 2007, 01:27 PM) [snapback]431800[/snapback]</div>

DO NOT DO THIS!!!
Frank Hudon showed us a burned-out Prius motor-generator (MG2) which he believes was caused by exactly this! Pressing on the accelerator tells the car to go, so it sends current to MG2. But holding the brake prevents the car from going. Since MG2 is connectred directly to the wheels via a reduction gear, it cannot turn with the car standing still. Thus you are sending current through MG2 but not allowing it to turn. Result: one burned-out motor!!!

<div class='quotetop'>QUOTE(DaveLeePrius @ Apr 28 2007, 09:41 PM) [snapback]431986[/snapback]</div>

The EV button would not help in this situation. With the SOC at 2 bars, the car would simply refuse to go into EV mode.

To the original poster: I agree that it is annoying to have the engine turning on and off so much. However, think how much more annoying it would be to be sitting in traffic and have the engine running constantly and burning gas the whole time!

My advice: Set the A/C temp where it is comfortable for you, and learn to live with the engine behavior, because it's the reason you are burning a tenth as much gas as every other (non-Prius) car on the freeway.

 

Lol, how simple and how true!

 

The same thing happens to me in traffic. Hell, my ICE comes on in reverse.

I keep my A/C at 76 in the spring. I will likely bump it up to 78/80 in the summer.

Whoever said leave a long car length in rush hour traffic must live in an area with no road rage. Sorry, that's just not practical in metropolitan driving. I don't see motorists in LA or DC tolerating that sort of thing.

Any Florida or South Louisiana people care to chime in? You guys don't get the higher temps like TX, AZ, NM, UT, MT, southeastern CA and NV do. However, you definitely get the humidity.

 

<div class='quotetop'>QUOTE(local_host @ Apr 28 2007, 03:17 PM) [snapback]431797[/snapback]</div>

Dude, get a grip. It's completely normal for the engine to do that under those conditions. I live in Dallas also, so I know whereof you speak and I sh!t thee not. Just set it and forget it. Think about all the gas you're *not* wasting.

Us hot-climate dwellers most definitely want to leave the windows up and the A/C running as fast necessary, not only for our own comfort but also to keep the battery and its electronics happy. They are cooled by cabin air (that's the vent to the right of the rear seats), not outside air. Rolling down the windows on a hot day, moving or not, could actually reduce overall fuel economy because the battery system would eventually get too warm to run efficiently.

 

<div class='quotetop'>QUOTE(local_host @ Apr 28 2007, 02:11 PM) [snapback]431768[/snapback]</div>

Hi Local. Sorry your having such a time with the texas heat and the operation of your prius. Many thoughtful folks have offered some good advice here. You seem to revert right back to the awful heat issue. I live just north of Houston and for almost 30 years have dealt with the Texas change of seasons. I am also on my second prius (had an 06 and liked it so much I purchased a 07). Most prius drivers fall between those that practice no hypermile techniques (just drive it as a normal car) and those that are determined to get every efficiency out of the car. I think you will also find that most folks would agree that under certain conditions the starting and stopping of the ice is more noticeable. When taken in context of the overall positives surrounding the car - the occassional notice of starting and stopping of the ice is a small discomfort for most of us. In my two years of prius driving in Houston I have had to deal with the same heat and humidity that you are dealing with - its just not a problem for me or most of the thousands of other prius drivers in texas. The one thing most try to do on this forum is to remain polite. So politely I would like to ask you to lighten up just a bit on how bad you perceive texas temps to be. My job requires me to travel and I can say that my perception is that most places in the US have less than comfortable conditions at some time of the year - and the residents just adapt or move. Give all things a bit more time and if you just can't live with the car or the temps - you have options.

 

Seems like this is part of the "idiot-light" nature of the Prius. The car is so automatic it won't let you make any decisions. You should be able to let the ICE run so you could charge the batteries if that is what you want to do, just like you should be able to turn regenerative braking off. Hopefully, Toyota will make the next generation less microwaqve appliance-like, and let the driver make decisions.

That is just plain mean!. If you really are an M.D., you should know different folks have different reactions to heat!

 

In hot humid weather, there are six things which will help keep you cooler inside a car.

1) Not sitting in direct sunlight:
If the sun is hitting the driver, but not the passenger, the driver will feel hotter. Window film like the Huper Optik as noted above will help. It will also help lower the overall heat gain for the rest of the interior - but not sitting in direct sunlight is the more important factor.

2) Lower the humidity:
With lowered humidity, your perspiration has a better chance of evaporating and helping cool your skin. Put the A/C controls on recirculation. Every time warmer humid air passes the cooler air conditioner evaporator coil, humidity is removed from the air. With the system being on "recirc" rather than fresh air, the interior humidity levels will drop. (This helps #6 with its contribution.)

3) Keep hydrated:
Drink water. (This also will help #6.)

4) Wear appropriate clothing:
This is no time for a dark wool suit and tie. Shorts and a light colored cotton or cooling synthetic fabric shirt is what is called for. (Again, helps #6.)

5) Cool air:
During hot humid days, the only place you are going to get cool air is from the A/C compressor and evaporator. It must run . . . but you shouldn't need MAX COOL to stay cool.

6) Airflow!!!!:
Dry air blowing across your skin helps keep you cooler. Set the A/C to blow directly on you from the vents in the dash. The cooler the air is, the less air movement you need to stay compfortable . . . but that may not be the most efficient way of keeping you cool. More airflow, less cool also works!

Doing 1 through 4 and 6 will lessen the amount of time the compressor needs to run in order to keep you cool . . . thereby saving gas and that annoying cycling of the gas engine.

Adjust any or all of the above to your liking, but for better efficiency and less gas motor start stop cycles, set the temperature higher, but only to a point where you can still keep yourself cool with higher airflow.

If you are going to run the A/C at MAX COLD anyway, don't complain about the Prius cycling the gas motor on and off. At least IT knows what it is doing for max fuel efficiency.

 

In the Civic Hybrid, the motor and the ICE is bolted together, so they always runtogether. WHen you back off the throttle in the Civic, all the valves close, and fuel injection ceases, so you get close to a zero drag when the engine turns with the motor. The Civic is cheaper, but with a rear seat that does not fold, and a smaller truck than a regular Civic, it is much less flexible with what it can carry. The Prius will also outaccelerate the Civic hybrid, and should get better city mileage--highway mileage should be about the same. You also get several options on the Prius not available on the Civic. If you can get used to the quirks, you will probably be happy with the Prius--I just wish they would go further with the Prius setup, as I mentioned.

 

<div class='quotetop'>QUOTE(Per @ Apr 29 2007, 05:27 PM) [snapback]432210[/snapback]</div>

These are features, not bugs. On average the car does a better job managing itself than most people could or would. If Toyota allowed drivers to turn these features off most of them would start complaining about reduced fuel economy.

 

Why would turning off the regenerative braking hurt fuel economy? The whole idea with pulse and glide is to fool the car to turn off regenerative braking, which comes on automatically when you release the accelerator. Having a switch would make it so much easier. As far as having a say-so on when the engine runs, while it may reduce economy, it would eliminate an annoyance as stated by the original poster, and I get the impression he would sacrifice economy if he so chooses. The Prius would still get better mileage under those conditions than other cars!