First 5 minutes MPG

Lower MPG is normal for any engine until it reaches normal operating temperature. Just imagine how much fuel you need to heat 300+ pounds of steel and aluminum up to 180F.

 

Look into the block heater if it bugs you. Especially with your location, it'll help doubly in winter. A couple of hours raises coolant temp by around 25C. By design engine will start shutting well below aforementioned 180F, more like 120F.

We use block heater year round; it gives a modest head start on warm up, and I think stresses the engine less.

The part is $80~, maybe difficult to get from Toyota USA? Which is a little puzzling, considering the realities of northern US states winters.

Dealership installed will maybe be around $250~350? There's a reason for that: it's a royal pain, very hard to reach, and a ton of cables right in your way.

Here's some info:

Block heater failed | PriusChat

As shown in above, ours failed after about 9 years of year round use. First one was dealership installed, full price at time of car purchase. Next one I did myself, but again, bit of a pain.

 

Just about every automobile gasoline engine with electronic control is programmed to burn a lot of fuel in the first few minutes. This is deliberately done to rapidly raise the internal temperature of the engine. This is because the internal engine temperature is one of the most powerful influences in raising efficiency and reducing tailpipe emissions.

So the operating theory is to waste a little fuel for the first few minutes to make the rest of the trip clean and efficient. It works well enough that it has become a universal practice.

 

You have the theory almost right but the details are way off.

When cold, a gas engine needs to be a little richer to run smoothly.
A rich mixture causes LOWER combustion temperatures, not higher.

When cold, the engine runs on purpose to warm up, the engine and the CAT.......longer than it might need to just for propulsion.
It is richer so that it runs good.

AND it is also typical to be in a "stop and go" situation right after starting.
Every start from a dead stop reduces your efficiency.

So the answer to the original question is:
Yes, absolutely normal.
Unless maybe you live at the top of a mountain and the first 5 miles is all downhill.

 

I wrote all of your block heater info down on my project sheet. Looks doable but like you said...it sure looks like a chore to get to! Appears that it 'clips' in.....it doesn't screw in..correct?

Might be good to do it when I do the EGR maintenance on our 2010 ( yes..I have been putting that off ).

 

They must be the details you imagined.

I deliberately wrote my statement in very broad terms to keep it brief. I'll try and keep it under 3 syllables for you next time.

 

The main point is just plain wrong.
If you want a gas engine to generate more heat, you do NOT run it richer.
A leaner mixture is hotter.

 

Thx for the info...seems a block heater would also be better for emissions as well..right?

At any rate...my thinking is that warm=good in the winter.

 

Yes, slightly.

You don't have to use Toyota's heater.
There are several styles available.

I got an external magnetic one for my diesel tractor.
And then found that the oil pan is NOT magnetic.
Sounded like a good idea.

 

Sam, you're getting yourself worked up defending a point that I am not disputing.

You are arguing that a lean mix burns hotter than a rich mix. Ok, that's completely true, but it was never in contention.

My point was that the startup mix is optimized for warmup, without touching the nitty gritties.

Still want to attack that?

 

It pushes into a bore, and there's a tang at the collar that snaps into place to keep it falling out.

There's also a bejeesus great rat's nest of conduits that also keep it from falling out, and make install a nightmare. When everything's assemble it all fits, but to back the block heater out of it's lair requires removal of a few cable bracket bolts and pushing/pulling/prying with all your strength to get all the #$@! cables just barely far enough out of the way.

And somewhere in that process, preferably at the very last moment, you have to butter the thing up with the heat transfer grease. I believe it's best to get it started in dry (just to ensure it's possible), then back it out, set it slightly askew right at the entrance, apply the grease, then back in it goes. Try to twist and send it straight in, to avoid promptly scraping the grease off. And you're doing this buttering with one arm on either side of the drive shaft, pretty much blind.

This is from below. Not sure if it's any easier from above. The latter does entail wiper and cowl removal.

 

No need for an "attack".
Your post speaks for itself.

What you said is absolutely wrong.
Maybe you didn't MEAN it the way it came out ?

I quit.

 

Sunlight and birdsongs return

 

'Ignore'ance is bliss.

 

His point was that the engine burns fuel at a high rate during warmup. And that is exactly what I see when watching the fuel burn rate display, in gallons per hour, on my ScanGauges. At startup, my engines (multiple cars) initially idle at a high burn rate, which in cold weather can reach around 1.0 gal/hour, then very quickly drop off as the engines warm. When fully warmed, my old Subaru would settle down to about 0.25 gal/hour, my current Subaru settles to 0.20 gal/hour, and my Prius goes into auto-shutoff when it gets down to 0.2 gal/hour.

 

This is where plug-ins, even with short range, deliver tremendous fuel economy.

 

Think that's bad just wait til winter, you'll get even low MPGs on non hwy trips. Get on the EGR stuff soon.

That's a great thread to refer back to. Is your car garaged with the block heater on? Or is it parked outside with block heater extension cord?

 

Ok...the block heater project just moved lower down on the list.

 

Is that really true though? I seem to recall that in environments that need a block heater, a plugin will start the engine to provide heat...correct? Yes, the prime has the heat pump...but it only works down to 14 degrees F. That is nothing here in MN in the middle of winter.

How does the heat pump work in a Toyota Prius Prime plug-in hybrid?

Now...a plugin AND a block heater...now we're talking!