Wait for engine warm up question.

No need to wait for a warm up. Just get in and drive. For best mileage, try to take it easy on the gas for the first mile or so.

Tom

 

Back in the days of carbs, it was necessary to warm up the motor a bit or the motor would stall/stumble. The Ford worktruck at my hobby farm has a hand choke, and if I don't warm up the motor at least 3 mins, it runs poorly.

I have never warmed up any fuel injected vehicle in moderate temps. In bitter cold temps, 2-5 mins just to make sure the front and rear windows are clear

 

The only reason I know to let any car warm up is if you literally want to get it nice and warm inside on a cold day. Other than that, except for the situations noted by jayman, it's not necessary to let the engine run before you drive it and in fact it just wastes gas.

The Prius has a "Ready" light on the dashboard that comes on after you start the car. It's there because you won't necessarily hear the ICE come on when you start it, so it's just the car's way of telling you that everything is good and you can start driving now. The light comes on a few seconds after you power on and then you're ready to go.

 

Yup. "Warm it up" advice is about 40 years out of date.

 

It also used to be that you wanted to give the engine a few seconds to get oil flowing and all of the lubrication working, but the starting sequence for the Prius engine is entirely different. The Prius uses one of its electric motors to spin the engine up to speed and only applies fuel and spark once oil pressure is established. It's not a slow, clunky start like you get with a normal starter.

Tom

 

I will disagree with everyone else. Letting the car warm up should be better for FE.

There was a discussion on this, http://priuschat.com/forums/prius-technical-discussion/31737-question-ice-warm-up.html

This is what I wrote,

Quote from Ken,

 

The fastest way to warm up any car is to drive it, gently for the first few minutes. Idling certainly warms it up, but that burns gas without moving you anywhere. Better to be moving and not get zero MPGs for that time.

ScottY, does scanview indicate whether energy is flowing from MG1 to MG2 during the initial 57 seconds (the "warmup" period)? In other words are we certain that the system merely throws away the heat energy created in the first 57 seconds instead of making it available to move the car?

 

During my S1a 57 sec warmup I drive to the exit of my subdivision around a steady 10-20mph. Using HV AMPS on the ScanGauge I notice that there is battery draw to accelerate but after that the engine will give me about 5amp battery charge and power to hold or slighly gain speed. If your first minute of the drive is under 30mph or if you do not need heavy acceleration then just drive it. Not worth driving 0 miles to warm up the engine.

 

Richard,
CANView shows the charge in/out of the HV battery only. Like I mentioned before, if you drive during the first minute, majority of the energy comes from the battery base on the large current draw reading and almost steady engine RPM.

 

Thus the proviso about driving gently for the first minute. If one *needs* to go fast or accelerate hard then MPGs are clearly not the priority :_>

 

So those measurements don't actually prove that the engine is providing none of the motive power during that first minute? It still seems unlikely to me that Toyota would design the system to run the engine but not use any of its output for propulsion, even for that short time.

 

A cold ICE is very much less efficient than a warm ICE, and also produces very much more pollution than a warm ICE.
Most of the energy stored in the battery was produced by the ICE while it was warm, so battery power is only a little less efficient and produces (indirectly) only a little more pollution than a warm ICE. Forcing the ICE to put out power while it's cold multiplies the amount of pollutants and wasted fuel.
Therefore it is better to let the ICE warm up a bit before forcing it to put out much power, because until then, the battery power is more efficient and less polluting.
That's why Toyota designed the system to run the engine, but not use any of its output for propulsion for that short time, and use battery power instead.

 

How much fuel is being wasted while not moving vs. the extra fuel (and subsequent pollution) of moving while the engine is still warming up?

I just don't see how running the ICE while you are not covering any distance as being more efficient in terms of fuel used and pollution produced, than driving while the ICE warms up.

* This is based on driving it carefully for the first few minutes of course. If you are flooring it within the first minute then you either have a crappy commute or need to grow up. LOL

 

I have never warmed up an engine before driving and I have never broken one. Even when my cars had manual choke, pull it all the way, start the car, push in to smooth idle, drive of easy.
Better to warm up by driving as warm up is more even with the water pump circulating the coolant around the engine and you are getting something from the fuel not just a warm exhaust. Power must come from the ICE during warmup in a Prius or the engine revs wouldn't increase when you press the accelerator, which they do.

If you have 2 minutes of travel on neighbourhood streets that will be all the warm up you need, although I wouldn't have a drag race with a ricer until you have been driving over 5 minutes.

 

A lot of idle time will also cause a dramatic increase in blowby, thus more oil contamination. In particular, diesel engines are subject to something called "wetstacking" if extended idle time occurs. You can really bugger a diesel engine with a lot of idling, though a lot of urban legend maintains that somehow idling is better for it

I guess if you have to ream it once you leave the driveway, then maybe a warmup might be needed. But what about the cvt? That only warms up in use

Consider emergency equipment that - at a moments notice - must perform. I'm thinking of fire trucks, ambulance, police cars, and emergency generators

Diesel powered generators, fire trucks, and ambulances - at least up here - are kept in climate controlled enclosures. No cold soak to worry about. Most have a power plug that is always plugged in, this maintains the batteries and usually runs a thermostatically controlled block heater 24/7.

The fire truck or ambulance also has a separate system - usually a 120 v compressor - to keep the air tanks full. Otherwise, you'd need to go and the Wig Wag would drop down, forcing you to wait until the engine compressor pumped up enough pressure to release the brakes

With that fire truck or ambulance, once you turn the key past Lock, an automatic ejector pops out the cord. You start the engine, turn on the disco lights and siren, and floor it

WIth the generator, the thermostatically controlled block heater keeps the coolant near 160 F all the time. When the power fails, the auto transfer switch will start the generator, wait a few secs, then switch the load from line to generator.

In the above cases, the motors appear to last a long time

WIth police cars, the vast majority are gasoline engines, the typical Ford Crown Vic. Some are kept in garages, most are left outside in the weather. Even at -40, the officer can't afford the luxury of a warmup, in an emergency call he starts the car and goes full speed. Very rare for a motor to blow

Since I have a heated attached garage, even at -40 I never "warm up." I start and go. If I had to park outside, I'd start the motor, then go outside to scrape the frost off the windshields. Then hop back in, and slowly drive off

 

I'm confused as to how they accomplish this without a clutch.

When the ICE is running, the planet carrier in the PSD is rotating.

How do they keep the planet carrier from applying any torque to the ring?

 

By spinning MG1 in the opposite direction.

Tom

 

The amount of torque that is transferred to the ring gear from the planet gears is regulated by the amount of torque applied to the sun gear by MG1. If the sun gear applies no torque to the planet gears, then the planet gears apply no torque to the ring gear.
Maybe you can visualize it better by first imagining the PSD without the sun gear. Without the sun gear, the the planet gears would just freewheel around the ring gear without applying any torque. Then imagine slowly inserting the sun gear into the middle, but first spinning it to match the speed of the planet gears so that it doesn't apply any torque. In effect, the MG1 driven sun gear is counter spinning the planet gears just enough to cancel out the rotation of the planet carrier.