Toyota Prius Forum banner
1 - 17 of 17 Posts

·
Registered
Joined
·
19 Posts
Discussion Starter · #1 ·
i live in DC and it's kind of cold right now -- 34 degrees outside. Do you warm up your prius in the morning by letting it idle? if so, how long? thanks
 

·
Registered
Joined
·
2,243 Posts
You will find the Prius warms up very quickly. There is also a supplemental electric heater which kicks in before the ICE takes over the heating duties. You're just wasting gas if you "pre-warm" the car.
 

·
Registered
Joined
·
2,285 Posts
It used to be axiomatic that you must warm up your car. There were several reasons:
1) The choke was required to run smoothly, but that limited RPMs so you needed to get "off the choke cam" before driving off. Anyone else remember manual chokes? Carburetors?
2) You needed to warm up the thick monograde oil so it could splash lubricate the cylinders, and so it could work it's way through the galleys to reach all the moving parts. Anyone alse remember monograde oil?
3) A common claim was that "90% of engine wear occurs in the first five minutes of operation," but this may no longer be true, with better materials, machining, and multigrade (or synthetic) oil.
4) The differing expansion rate of metals means the tolerances whenn warmed up are not met when cold. However, better materials and CTE matching mean this tolerance problem is less than it used to be.
5) Lastly, automakers wanted you to drive off quickly to help warm up the motor, this being part of the EPA cycle for warmup. To get fewer test emissions, they haad to start driving sooner, eliminating warmup. Then they had to tell US to do it or they would be subject to a claim that the testing was not realistic. But the motors still needed warmup for the reasons above.

I still warm up my air cooled VW, since it is an old design, and takes a long time to warm up evenly, being air cooled, and the mismatch between the alloy block and heads, and steel cylinders and pushrods, make for wildly varying valve clearances during warmup.

But new cars only need a minute or two, and I do that more to make sure all fluids are circulating and the temps are rising as they should (no stuck thermostat, for example). This is where Hyp's gauges would come in handy.

Modern fuel injected cars use extra injector duration, not a choke plate, to enrichen the mixture when cold. There is no rpm limit during warmup. This was also done to reduce emissions, and the faster warmup also means less carbon deposits from burning cold rich mixtures.

I have a long downhill drive to start my commute, so it runs for about a minute before I put a load on it whether I warm it up or not. If I didn't, I'd probably still give it about a minute, then drive off.
 

·
Registered
Joined
·
171 Posts
Ditto red, even a minute or two is not needed. The only time I will "warm up" my Prius are on those rare days that, even with scraping the ice off the windshield, as soon as you pull away the inside or outside frosts up again.
 

·
Registered
Joined
·
26 Posts
Do you warm your Prius Up?

SgtKarl said:
Ditto red, even a minute or two is not needed. The only time I will "warm up" my Prius are on those rare days that, even with scraping the ice off the windshield, as soon as you pull away the inside or outside frosts up again.
I cannot figure out why my Prius frosts up so fast on the inside of the glass surfaces when I have my girlfriend as a passenger! I wonder if there is anything else I could do to prevent this besides running defrost? :wink:
 

·
Registered
Joined
·
111 Posts
I never warm up my Prius. One cold day, about 5 below, I started out as usual. A lengthy hill near my home seemed to demand higher revs from the gasoline engine. It made me wonder if the battery wasn't putting out as much electric power at that temperature.
 

·
Registered
Joined
·
4,873 Posts
Re: Do you warm your Prius Up?

SgtKarl said:
Ditto red, even a minute or two is not needed. The only time I will "warm up" my Prius are on those rare days that, even with scraping the ice off the windshield, as soon as you pull away the inside or outside frosts up again.
I cannot figure out why my Prius frosts up so fast on the inside of the glass surfaces when I have my girlfriend as a passenger! I wonder if there is anything else I could do to prevent this besides running defrost? :wink:


From now until the middle of march as soon as I hit the start button I go right to the windsheild defrost button on the steering wheel. Some times it works!
 

·
Premium Member
Joined
·
888 Posts
Rich D. said:
I never warm up my Prius. One cold day, about 5 below, I started out as usual. A lengthy hill near my home seemed to demand higher revs from the gasoline engine. It made me wonder if the battery wasn't putting out as much electric power at that temperature.
That is a correct conclusion. The battery was so cold that its output was severly diminished and as such the ICE had to direct drive MG1 to provide enough power for MG2.
 

·
Registered
Joined
·
6 Posts
Warm up or not!

I warm my Prius up.

First point: I live in the Dallas/Fort Worth area of TX.

I warm up 30 to 40 sec., thats how long it takes until the ICE shuts down and I can start in EV mode.

If I did not warm up, but start to drive my MPG is down to 12 or 15 because the ICE is engaged.

When I warm up first, my first mile which is down hill, is over 99.9 MPG.

I do know that the ICE at idle use less fuel, then when it is under load.
 

·
Registered
Joined
·
171 Posts
Re: Do you warm your Prius Up?

littleboy said:
SgtKarl said:
Ditto red, even a minute or two is not needed. The only time I will "warm up" my Prius are on those rare days that, even with scraping the ice off the windshield, as soon as you pull away the inside or outside frosts up again.
I cannot figure out why my Prius frosts up so fast on the inside of the glass surfaces when I have my girlfriend as a passenger! I wonder if there is anything else I could do to prevent this besides running defrost? :wink:
Ask her to "Please stop talking" I won't GO to the other possibility! :D
 

·
Registered
Joined
·
26 Posts
Re: Do you warm your Prius Up?

SgtKarl said:
littleboy said:
SgtKarl said:
Ditto red, even a minute or two is not needed. The only time I will "warm up" my Prius are on those rare days that, even with scraping the ice off the windshield, as soon as you pull away the inside or outside frosts up again.
I cannot figure out why my Prius frosts up so fast on the inside of the glass surfaces when I have my girlfriend as a passenger! I wonder if there is anything else I could do to prevent this besides running defrost? :wink:
Ask her to "Please stop talking" I won't GO to the other possibility! :D
It is when we BOTH stop talking and focus on other activity that the frost/moisture build-up on the inside glass surfaces intensifies. Should I run air conditioner and bring in fresh outdoor air to clear the humidity build-up? :wink:
 

·
Registered
Joined
·
171 Posts
Re: Do you warm your Prius Up?

littleboy said:
It is when we BOTH stop talking and focus on other activity that the frost/moisture build-up on the inside glass surfaces intensifies. Should I run air conditioner and bring in fresh outdoor air to clear the humidity build-up? :wink:
Well, if you're serious, A/C is the only way to go if it is frosting on the inside. When I bring in outside air, it just gets worse. A/C with interior air only (recycled)
 

·
Registered
Joined
·
211 Posts
redwein said:
Warming it up is not necessary and will only reduce your MPG.
Running an engine hard before it's warmed is bad for an engine, and also increases polution as the CC isn't fully warmed yet.

On a prius though, letting it rev in neutral to warm up is unnecesary. Unless one is drag racing, the Prius ICE tries to run at peak efficiency revs and not run hard, so it will warm up pretty much the same in neutral or drive, only you'll be gettign somewhere in drive. :D

However, the engine does need to warm up a bit, even with the thermos. So, running it really hard on a cold morning before it's 100% warmed up is still not the best idea. No drag racing on a cold engine.
 

·
Registered
Joined
·
211 Posts
Re: Warm up or not!

Paul H said:
When I warm up first, my first mile which is down hill, is over 99.9 MPG.
lol. well downhill should always be free or close to it. But regardless, short term MPG doesn't mean much. You have to remember you already used gas to warm the engine and store energy for the battery.

For example, if you're running on full electric, your MPG is momentarially infinite, as you;re buring no gas. But obviously that has to be averaged with the gas you actually combusted to store than energy.

Long term averages mean much more.
 

·
Registered
Joined
·
14 Posts
Re: Do you warm your Prius Up?

SgtKarl said:
littleboy said:
It is when we BOTH stop talking and focus on other activity that the frost/moisture build-up on the inside glass surfaces intensifies. Should I run air conditioner and bring in fresh outdoor air to clear the humidity build-up? :wink:
Well, if you're serious, A/C is the only way to go if it is frosting on the inside. When I bring in outside air, it just gets worse. A/C with interior air only (recycled)
But my girlfriend LIKES "frosting on the inside". She claims it adds to a sense of intimacy and deters probing eyes from outside the Prius! :wink:
 
1 - 17 of 17 Posts
Top