Prius Fuel tracking

<div class='quotetop'>QUOTE(DaveinOlyWA @ Dec 9 2006, 11:19 PM) [snapback]359948[/snapback]</div>

Unless I'm missing something here, I'm confused. When the car is cold, the cooling system's thermostat is closed. And when it's closed, it doesn't matter how much air goes--or doesn't go--through the radiator as there's ALMOST ZERO communication (usually a tiny by-pass hole; just-in-case) between the coolant in the block and that stored in the radiator. Through-the-grill air will ventilate the engine compartment, but shouldn't affect warm-up time. Are you certain you notice a faster warm-up? If so, why might this be?

I recently did a lower-grill block-off (during a nasty cold snap) and what I THOUGHT I noticed was higher mileage figures in the 40-to-60 mph range, which was due to the aerodynamic improvement. Of course, I'm not absolutely sure on the mileage increase, it's just that I am pretty used to driving a certain way on a certain road at a certain speed... and could show 65-75 mpg (this is ICE/ON cruise) where I'm used to seeing 55-65 tops. Could be due to other factors, but this happened in the releatively warm afternoon right after I blocked the lower grill. If the weather gets really nippy again, I think I'll try the block-off again to see if I can re-create the effect.

GeronimoPFudgemuffin

 

Dave if finally blocked off the upper grill on her car with pipe insulation as I couldn't get it over about 74C and it took forever to get to that temp as well. My Classic would have been at 87C for at least 10 blocks before that point. After I blocked off the upper I finally got her car to 87C and after only a few blocks, so took it out on the freeway and it never went over 87C. Will ask her tomorrow how long it took to get to 87. I started out today with the ICE at 8C and it went to 26C with the thermos dump.

 

<div class='quotetop'>QUOTE(GeronimoPFudgemuffin @ Dec 10 2006, 01:55 PM) [snapback]360124[/snapback]</div>

you are right about that but wrong about the intent. my intent was to MAINTAIN hot temps. something that is nearly impossible to do at speeds of 35 mph or less. my commute is half 25 mph, and half 35 mph. i would literally run in warm up mode nearly the entire trip. at 5½ miles one way, my mileage would have plummeted.

seeing as this is the first time i have done this. i am seeing a good 2-3 mpg increase. granted i am talking about two different cars, (04 pkg #1 and 06 pkg #4) but the powertrain is fundamentally the same. what convinced me was two weeks ago we had a very cold snap. snow, temps as low as the mid teens (average low for Nov is 40-45º) still was able to maintain a 51-52 mpg tank. that also included a 150 mile road trip with several stops and 4 people in the car.

so the foam is to reduce the air circulation when the thermostat is open. iow, i want the thermostat to open and stay that way. before without foam, it was constantly opening and closing. with CANVIEW, you can easily see that just stopping at a long light was enough to kick you back down to warmup mode again.

example. winter average on my 04 mostly solo driving. (got serious with my SO in March of last year when she moved in with me) 49.52 mpg. that was 2 winters and about 12,000 miles

 

<div class='quotetop'>QUOTE(DaveinOlyWA @ Dec 9 2006, 08:19 PM) [snapback]359948[/snapback]</div>

You can borrow my ScanGage. I guess the new one is better more data.

 

<div class='quotetop'>QUOTE(hdrygas @ Dec 11 2006, 01:13 PM) [snapback]360565[/snapback]</div>

henry, i may have to take you up on that offer

 

<div class='quotetop'>QUOTE(CHART @ Nov 22 2006, 10:00 AM) [snapback]353051[/snapback]</div>

My 2004 is exactly the same. I tried to push extra gas in once, but it spilled out. Lesson learned. I usually fill up at two bars left with about 350 miles on the tank. During the summer I can push it to 400 miles. It would be nice to get another 100 miles, but that would only be an extra three or four days, so not a big deal.

 

<div class='quotetop'>QUOTE(Frank Hudon @ Dec 10 2006, 02:41 PM) [snapback]360142[/snapback]</div>

I was driving around today with the outside temperatures in the mid to high 50's (56 as I remember) I had the radiator blocker zipped up tight and pushed the engine temp to 205 F. I unzipped and checked in F and C. With the zippers open I could get the engine temp to 198 F or 88 C but not over. I would not mess with a radiator blocker in our climate with out a temperature gage.

 

205 isn't even at the fan "on" stage and or is pretty close to it, the antifreeze won't boil till almost 235F under the pressure in the cooling system. I had 97C on the big hill today, every day this week so far, and I'm so used to it I hardly ever look at the temps. I've only ever once heard the cooling fans come on and it only ran for about 2 minutes, because I had the heater turned way down. Your a long way from any damage to the car. I'd hazzard a guess that 100F and max A/C will have the temp up around 210 easy maybe higher.

 

well i've had mine blocked for probably at least a month, have made several trips to seattle and back and have not noticed anything that would indicate the car overheating. when i first did it and there were a few warm days (there were a few days when it was in the low 60's) on extended trips of at least 30 miles (one was 75 miles from Rochester to Port Orchard with only a 15 minute slow stretch over the Narrows bridge) every time i shut down, i would monitor the car. never once had the electric fans on at shut down so would have to assume that temps were ok. although, not really recommending that anyone else do this.

 

I did run out of gas once. Fortunately, I was a hundred feet or so from a station. The reason I ran out was because the actual fuel capacity is one gallon less than the book says. When the last square starts blinking in my Prius, you MUST find a gas station very soon.

 

DTE indication requires two pieces of information: Remaining volume of fuel, and miles per volume of fuel. Both of these are too variable to be reliable, making the DTE calculation too variable.

Engine temp is maintained by two factors: Thermostat setting and airflow through the radiator. When the thermostat is open, then the determining factor is airflow through the radiator. When not moving, the airflow is determined by the thermostat for the fan. When moving, the fan isn't much of a factor. So if you want a bit higher temps in the engine for cabin heat, then restricting airflow through the radiator can increase coolant temp.

Another factor that could affect coolant/engine temp to a lesser degree is cool air flow into the engine compartment, thus chilling the engine block itself. At nominal temps, this is not much of a factor, although at extreme cold, this could be an issue.
Also when ICE is not running, normally coolant is not flowing unless there is cabin heat demand in which an electric pump circulates coolant to the heater core. This too could cool down the engine.

 

<div class='quotetop'>QUOTE(jkm750 @ Nov 19 2006, 01:16 AM) [snapback]351597[/snapback]</div>

I have had no kick on the accuracy of my fuel gauge until a 500 mile trip I took over Christmas. On the road home I filled with gas about 150 miles out. I drove the 150 miles home plus another 125 miles around home and the fuel gauge has never moved off the full mark. Now I would like to think I was getting that good of mileage, but I know it taint so. Always before it starts dropping after about 125 to 140 miles.
Has anyone else run across this problem? If so what had to be done to correct it, replace the gauge or what????

 

<div class='quotetop'>QUOTE(Wetnabber @ Dec 30 2006, 08:55 PM) [snapback]368780[/snapback]</div>

Hmm, I filled my tank up a couple days ago and it dropped off the full mark after just 34 miles...then again, I didn't fill it much at all beyond the first time the pump clicked off, as it's been around 40 degrees or colder here lately.

Dave

 

ok, thanks to Henry (hdrygas) i have been tracking fuel consumption and water temps with the scan gauge.

couple of observations on OAT and how it HURTS!@!~!

i have a short commute, going its 5.1-5.2 miles, coming its 5.5 miles (one way streets involved is why its not the same both ways)

on mornings when temps were 45º- 53º, mpg to work, elevation +200 feet, about 47.3-50.5 mpg, max water temp 195-205º F

last 3 mornings
mpgs----- 44.1--42.9--39.9
water-----185---180--165!!
temps-----35----28----32.. (on this day, very dense freezing fog so dod use defrost more than normal)

after seeing that 30 something reading, i freaked out... checked all my tire pressures, (one was a pound low...) reread all my high mileage driving notes....

hope it gets better... by WARMING UP!!


but as far as blocking the radiator, i have also driven trips up to 50 miles mixed freeway and surface streets as warm as 60º and no issues. max water temp since i started monitoring has been 209ºF. only thing i do notice is the OAT is no longer accurate because of the reduced air flow in the engine compartment so i know the radiator block is doing something. i still have not heard the circulation fan come on one single time. if the engine was hot, it would still run a bit after the engine was turned off.

 

<div class='quotetop'>QUOTE(DaveinOlyWA @ Nov 21 2006, 09:18 AM) [snapback]352551[/snapback]</div>

Now I've never noticed the bars reappearing, but I have noticed with CAN-View, the % remaining dropping by 3% and then coming back up those same 3%. This is while driving, and I thought it might be related to the incline the car is on. I haven't been able to confirm one way or the other though. This was might first trip of more than 700 miles total since CAN-View was installed. There's just too much going on with CAN-View to keep track of. I noticed WOTMode for the first time this weekend too.

Dave M.

 

ok an update, last week, dry, cold at night but into the high 40's low 50's during the day. current tank, 410 miles 53.1 mpg... oh ya~~