Better to let run before shutdown?

It is definitely a thing with gen 3. Shutting down after a brief run can leave condensed water in the skinny EGR passages, and then on the next start the engine will bang like the hammers of Hephaestus for a long moment before smoothing out.

I haven't heard the same thing about gen 2.

But never mind all that, you don't need to start the engine at all to roll the windows up. You can just go to IG ON (two button pushes without brake), roll the windows up, and switch the car back off (one more push, no brake). No going READY, no starting the engine, no waiting.

 

For 20 years you have been making exposure to deadly poisons worse for you and your loved and you need to to stop! I have a stern lecture to anyone poisoning the air with long outdated beliefs like this. Here's 3 different reasons for why you need to stop doing that!

1) Long ago you needed to warm up a car engine, especially big trucks in cold weather because it took a while for the oil pump to get everything in the engine well lubricated... But as time went by and engines got more modern you no longer had the need to wait on lubrication to optimize.

2) Another reason people used to wait for the engine to warm up is because you needed the intake manifold and carburetor to heat up to better vaporize the fuel so the engine worked normally. When Fuel Injection came along in the 80's waiting for it all to heat up was no longer necessary.

3) "Existing literature, as well as analytical tools like the U.S. Environmental Protection Agency’s Motor Vehicle Emission Simulator (MOVES), indicate that while total vehicle emissions have dropped significantly in recent years, those associated with cold starts can still constitute up to 80% for some pollutant species. Starting emissions are consistently found to make up a high proportion of total transportation-related methane (CH4), nitrous oxide (N2O), and volatile organic compounds (VOCs). After 3–4 min of vehicle operation, both the engine coolant and the catalytic converter have generally warmed, and emissions are significantly lower." https://www.sciencedirect.com/science/article/abs/pii/S1361920915002229

and

"Toxins released during cold starts

• Benzene: A known human carcinogen and neurotoxin, benzene is present in gasoline and emitted during incomplete combustion, according to ScienceDirect.com and the Colorado Department of Public Health and Environment (.gov).
• Formaldehyde & Acetaldehyde: These are air toxins and volatile organic compounds (VOCs), which can contribute to respiratory issues and other health problems.
• Carbon Monoxide (CO): A colorless, odorless, and highly toxic gas that can restrict the blood's ability to carry oxygen and lead to serious health problems or even death.
• Nitrogen Oxides (NOx): These pollutants contribute to smog and can cause respiratory problems.
• Particulate Matter (PM): Fine particles released during combustion that can penetrate deep into the lungs and cause respiratory and cardiovascular issues.
• Volatile Organic Compounds (VOCs) and Intermediate VOCs (IVOCs): These organic gases are important precursors to secondary organic aerosols (SOAs), which have adverse impacts on air quality and human health."
• 
  From: https://www.sciencedirect.com/science/article/abs/pii/S0304389422007683

 

She's said she no longer drives a Prius in previous posts... If she was still driving a Prius she could roll up the windows and be done with it before the engine even started. I suspect the reason she's still on PriusChat is because her higher self is trying to get her back to one so she poisons the air around her way less.

As for water in the EGR passages that would be a problem on a car that's rarely driven, but that line of thinking seems like nonsense if its a daily driver.

 

For gen 3 it has been a nuisance known from the earliest days, with the first reports rolling in around October 2009 for spanking-new 2010 model year cars, only on a next start after a short no-warm-up run followed by a cold soak, with Toyota's response a couple years later in January 2012.

Water in the EGR passages isn't any great mystery, given that those passages carry ... exhaust, which is 13% water. It's usually there; I poured a noticeable amount of clear water out of mine when I cleaned the system.

Only, for it to fill the passages enough to be snorted into the intake on the next startup, it seems to take a short, no-warm-up engine run followed by a good while sitting cold.

 

Looks as if Kris' "let it run" mantra has some merit at least sometimes with the right rig, such as G3.

But I suspect her dad was was talking about less exotic rigs and if it was a good idea then, is it still smart to let it run a bit?

As a WAG, IT may have some merit,but...?

This would had been a great question for Tom&Ray on CarTalk. Heck, they may have covered it.

https://www.cartalk.com/

 

Thanks for clarifying... If I had to put blame on a failed EGR design causing headgasket failure in Gen3 Prius I'd put it on water... And if the EGR system can do that with water, then it makes sense that all your denialist nonsense that EGR in Gen3 is not responsible for premature headgasket failure has been yet again proven false. Gen3 EGR system was an incompetent design and destroys low mileage engines! Thanks for finally agreeing with us!

 

They actually did... I'm not going to dig that recording up but CarTalk laughed and told jokes like they always do and they were 100% on the side of start your car up and drive away (just be easy on it till it warms up) and don't be the dummy that poisons their family and neighbors with the most toxic air pollution you car is capable of creating by pretending that warming up a car engine has to be done before driving it to "protect" it. It does nothing more than make you a family and neighbor health ruining imbecile that doesn't realize how much hurt your old wives tales are causing people around you!