2017 Prius Prime (Plug-in Hybrid) Full Product Information & Technical Docs (PDF)

No. There is no real "cold" startup like a traditional vehicle. You have an engine optimized for rapid warm-up that's RPM limited by a massive battery.

 

a cold engine is a cold engine. you may not have heard of the massive problems people have had starting a cold engine and shutting it down. it is so bad, toyota issued a tsb, but the fix didn't take, and even the 2015's do it.

 

Yeah, but since the PiP can't turn off the cold ICE right away after using it to shield the battery/motors/whatever (in situations like this or this), there obviously is some sort of downside to killing a recently started ice cold engine.

 

yes, the potentially damaging crazy clatter of pistons and valve symphony.

 

Those assumptions are incorrect. There is no can't. The gas engine runs for the sake of lower overall emissions. You shut it off early, it's not as clean. It's that simple.

 

that's another reason i let mine run until it shuts off. if you shut it down early, you make more pollution than if you let it run for the 4 minutes or whatever.

 

Scenario 1:
PiP is running pure EV mode. 7 miles/km/whatever left. Goes downhill for about a minute with regen strong and long enough for ICE to kick in and "help" or whatever it does. PiP reaches bottom of the hill and keeps on going flat with the ICE turned on for two-three minutes more before switching itself off and continuing in EV mode.

Scenario 2:
PiP is running pure EV mode. 7 miles/km/whatever left. Goes downhill for about a minute with regen strong and long enough for ICE to kick in and "help" or whatever it does. PiP reaches bottom of the hill and immediately shuts ICE off as it's no longer needed. Continues in EV mode.

Scenario 2 doesn't exist.
How does the car emit more pollution in Scenario 2?
Does it somehow pollute more the next time the ICE is turned on than it did through the two minutes extra in Scenario 1??

I'm genuinely confused.

 

You need to learn about the emission system. Do some searches. There are countless threads at this point. The key is understanding catalytic temperature.

 

The converter doesn't need to be warm if you are going to run in Ev mode for the rest of the trip. If you're going to let it cool down anyway without using it, warming it up wastes fuel and creates emissions.

 

Definitely, but if the key to running the ICE longer is to warm up the cat, why switch off right after getting it up to temperature?
When the ICE kicks on in my downhill scenario, it's gonna be wasteful regardless, right? It's gonna pollute no matter what happens at the bottom of the hill. Now, as soon as I reach the bottom, you're saying it's gonna be even more polluting to kill the ICE at that moment and keep on going on electricity alone, than keeping the ICE on to warm up the catalytic converter to proper operating temps and THEN killing it.

 

Your scenario is well outside of the majority. Expecting the system to be optimized for that is unrealistic. You want to avoid gas user entirely, you should buy an EV instead.

It is affordably designed to be as clean as possible without knowing what you're driving plans are.

 

but it's the scenario we've been talking about for the last 3 pages. it began in post #51 on page 3.

 

The PiP is programmed to switch on the ICE in various scenarios. Mine is one of these scenarios. Engineers looked at the specific scenario of prolonged regenerative braking in EV mode and made sure the system was programmed so that the ICE switched on in that scenario. They made sure to program it so that the ICE didn't shut off as soon as braking was done and the car continued under its own power on a flat road again. You can be damned sure they didn't do it for emissions purposes as that makes no logical sense.

 

why can't the ice spin on a downhill run for engine braking, without ignition?

 

A theory I have, that isn't confirmed, is that the MG (either of them in the PiP, really) gets too hot from regenerating and needs to cool down for a while before working to power the car again and that the ICE switches on to propel the car forwards and let the MG(s) rest once the downhill portion is over.

But Redpoint5 has got temperature readouts that state nothing out of the ordinary, so I'm not too sure.

 

what is doing the regenerating in charge mode?

 

What do you mean? When the car is charging from an outlet, nothing happens between the battery and MGs.

 

charge mode is when prime engine is purposefully recharging the battery while driving.

 

Using the MG, then.
That would be like any normal Prius non-plugin behavior, except it will keep going 'till completely full or you switch it off.