Time to be a detective

When the Prius stars 'cold' it's primary focus is getting the Air pollution controls up to temperature. It only focuses on mileage once warm.


So grouping trips to stay warm, really helps

Grill blocking and Engine Block Heater can help when it is really cold out.

 

My Prius is a turd plopping dog in the mpg department when its in the warm up period.

But, on another note, what are your tire pressures at? If it was a salvage Prius, was it in a major crash and are all of the underbody wind deflectors in place, etc?

 

as a clue for us detectives, what are the long trip mpg's, and what are the short trip mpg's for each car?

 

What condition is the 12v battery in?

 

The consensus here is when the 12 V battery has been through a deep discharge, it's life is on borrowed time. It also can cause a reduction in MPG due to the engine having to run more than it normally would.

You could always stick a battery charger on it overnight and see if it helps. Or have the battery checked.

 

The package five, does it have larger wheels, like 17"?

 

My package #5 doesnt.

 

Wheels will make a big difference in mpg maybe 3-5 mpg, also check PSI on side of tire you might want to increase PSI a little bit. Do not go above max side wall posted PSI.

I'm no battery expert someone else will chime in I'm sure.

 

it's the difference in short trips that's baffling. it's like damage from the accident is causing it to warm up more slowly. i don't think the gen III has a coolant thermos, but is has exhaust coolant warming?

 

Maybe Toyota has a way to run a scan on the exhaust coolant warming system to see if it is operating properly!

 

40 PSI front, 38 PSI rear, that will help.
The 17" tires kill mpg too.

 

A difference of 8-10mpg cold is significant. IMO 34psi in a tire rated at 51psi is too low.

I'd buy a couple mpg for the tires & a couple mpg for the tp but I'd expect an effect on the hot number as well. A weak 12v battery would also affect both hot & cold numbers.

EGR valve?

 

The battery with a resting voltage of 12.43 is somewhere between 50-75% the capacity of a new battery. It should be ok, my car's battery is at 12.2V and i get better than that.

When i bought my car i remember reading an article with quotes from a toyota engineer explaining the warm up time on the gen3 is much quicker because it does recirculate the exhaust in such a way as to get everything warmed up. The time dropped significantly from 10minutes to 4 minutes. I would hook up an OBDII adapter with the torque app and log your engine temp over time. You have the benefit of 2 vehicles, so you can compare.


Actually i found a link to a similar article:
Tirekicking Today: 2010 Toyota Prius

So essentially the exhaust probably controls some sort of valve for running coolant around or running exhaust through a heat exhanger to speed up warm up time. If said valve was unplugged, wiring cut, or damaged and inoperable. Your warmup time would be like a gen 2.