Warm up time?

since you are not driving an "old school" vehicle, time to go back to class!!

think about what your Prius does and lets compare that to old school thinking.

you heard, its better to leave it running, especially in winter, because the extra wear and tear on startup right??

if that were the case for the Pri, i would have a warranty measured in feet, not miles since the engine is constantly starting and stopping all day long

and lets face it. we all know we are not driving our daddy's Chevrolet!!

 

Funny!

 

While it may not be Dad's Chevrolet, it is still an aluminum piston, steel cylinder, water cooled reciprocating gasoline engine with plain bearings. I see many similar things and almost no differences.
And no, I'm not talking about leaving it running, I'm talking about letting it run for the minute or two that it runs prior to shutdown, first start after sitting for a while.
Why do you think it runs for a min or two first thing in the morning? Maybe the Toyota engineers who designed it need to go back to class because clearly there is no need for a warm up. That one or two min run isn't enough to get to stage four, then what's it for? If it were to lite off the cat, that could be delayed until the SOC dropped low enough or throttle setting called for the ICE.
Apparently programming calls for initial heavy use of the traction battery until the engine runs a while. Don't see how being easy on engine use early on reduces emissions as all vehicles that I am aware of including the Prius run at a higher than normal RPM while cold, putting more fuel and therefore heat into the cat for early lite off, Do you think the Prius engineers could be old school too? Maybe want to let a little heat and oil circulation to happen before the engine is put under load?
Since I can detect no drop in mileage and get 60+ MPG by allowing it to warm for the one to two min. in the morning, I'll stick to that.
It's been a while since I put more than 200,000 miles on a vehicle before selling it, I plan on returning to that with this Prius, so I don't mind wasting that one min. every morning.
I'm not saying if you don't warm yours it won't last until well after the warranty period, I believe it will last through warranty even if you drive it like you stole it, but I do believe that if you want it to last for a very long time, then allowing a little heat into the engine before you jump on the highway is in order. I don't see anything "new" in the Prius engine to change that.

 

and sometimes a warmup is unavoidable especially if its first thing in the morning after an ice storm and you have the desire to be able to see where you are going.

in those cases, only with the defrost on will the engine stay running so there is a way to warm it up.

 

I've heard that under the current EPA rules that the emissions control must reach their proper temperature within some set amount of time. Don't know if this is true or a myth. (It might have something to do with why GM keeps saying the Volt is an EV with an ICE backup) In any case, if true, the rule has to change for a real PHEV.

But...


"The EPA says letting your car idle to warm up doesn’t really help – it actually burns more gas to let the car idle than you can save by letting the engine warm up. "

source: Increase Gas Mileage | Fuel Mileage | Better Gas Mileage

This is a generic statement, not aimed at the Prius and it discusses FE not anything about emissions, engine life, etc.

But things have changed since the old school times. Engine manufacturing is much tighter, for example. And you can't (in the Prius) excessively rev the engine when cold. And there is no jerky starter motor that spins the engine before oil is being pumped.

3PriusMike

 

My recommendation is stand still warming up for the first one minutes, Stage-1a.

During the Stage-1a, the ICE runs for warming up the coolant and catalyst. The ICE does not drive wheels, therefore Prius is driven by electric only. Then, it causes the battery SOC down.

After the Stage-1a, Prius goes to Stage-1b until the coolant temperature reaches to 104F or Stage-2 above 104F.
On both cases, the ICE provides driving power, so you can now drive your Prius.

Ken@Japan

 

Does stage 1a only last one minute, even in very cold days?

 

My experience is only down to 32F.
I would like to hear other experience who has the ScanGauge below that temperature.
During the Stage-1a, we see the ignition timing is after the top dead center.

Ken@Japan

 

going from S1, the ecu's are programmed to use more traction battery for that very reason ... to save fuel / improve mpg's while the ICE is at it's coldest

ZERO charging takes place while in neutral
.

 

True, but I'm in Park. If the energy monitor can be believed, charging occurs in Park

Ken 1784 knows far more about this thing than I do, that's obvious. I'm following his recommendation:thumb:

 

In my (limited) experimentation I noticed the Prius keeps the ICE spinning more often when in power mode, even when the engine is fully warmed up. I was driving around in the the mountains with the coolants temps around 185F and it still seemed the ICE was running more often. (When in motion.) Everything is still shut down when stopped, though.

I tried using power mode during warm up on the way to work today. (Only about a 13-14 minute commute all on surface streets with lots of stop and go.) Not sure it helped. When I arrived at the office, coolant temp was only 164F.

I'll try it on the way home today. (Which seems to yield slightly better mileage as it's slightly downhill.)

Anyone have similar experience with power mode and ICE spinning? It could be a good qood way to speed up warmup if it's valid. Overall warm up really kills my commute mileage since my average speed to work is only about 13mph which doesn't give the engine any time to warm up and get to full hybrid operation.

 

That's true, it's been that way since at least the mid 70's. I believe it's the reason for the initial high idle of some cars, to get enough heat into the cat for it to lite off in time. I believe there are several electrically heated cats for that reason also. American cars supposedly have the cats very close to the engine so they will lite off early, whereas Euro spec cars have the cats further back to keep them from overheating from high engine speeds, or at least I was told that in Germany, don't know if it true, but it did sound logical.
There are of course very specific rules for EPA testing, and you would be foolish if you don't think the manufacturers learned early on how to "game" the system.

 

Surprised people haven't commented more on this. This goes against the conventional wisdom typically espoused on this forum of just start the car and go (albeit keep it low on the RPM's). Still, what Ken says seems to make perfect sense...

 

Most conventional wisdom is still true, but Prius is a different animal, and sometimes because of it's unconventional operation, what works on other cars may not be the best here. My biggest problem is a lack of knowledge.
I wish there were a "theory of operations" manual that explained what, when, where and how.

On edit, Sometimes it seems there a few knowing individuals that seem to interject every now and again and bring the neophytes back on track. Being a conspiracy theorist, I would think Toyota would be foolish not to monitor something like this forum

 

Do you know if this warmup should be done in park or in neutral?

 

My previous car was a BMW the cats (two of them) were inside the exhaust headers bolted directly to the cylinder head.

I will go with Ken's recommendation on warm up, it makes good sense and he is usually right. I'll let it warm up in park because in neutral it can't charge the battery. I'm not sure it will charge in stage 1a anyway but I know of no reason to use N.

Point of interest: The Gen3 Prius routes engine coolant around the exhaust system behind the second catalytic converter to help warm up the engine faster. This replaces the "thermos bottle" we had on the Gen2.

 

I believe most BMW's are assembled in the US now, and that was in 1994, and maybe things have changed, or maybe it was never true. All cats way back when used to be back like mufflers, and now they do seem to be very close to the engine.
For all I know maybe Euro spec cars still have the cats further back, or maybe they never did?

 

I think the early ones may have been as you said. Mine was an E46 which were manufactured between 1999 and 2006. Yes they have a factory in North Carolina I believe and another in South Africa. Mine came from Munich and I used to curse at it in German.

The diagram I have of the Gen3 exhaust shows two cats (in series) right after the manifold, then behind the second cat is the coolant recirculation piping and the muffler after that.

 

I would assume Park as no battery charging can occur in neutral. I was hoping Ken would answer your question as I'm only assuming.

 

Our recommendation is in Park position.
In Neutral, everything is out of control, which means engine will be continued to run even if warm up was finished.

Ken@Japan