6th gear and Scangauge

Mine's already calibrated and I think my % is about the same as yours. I still wouldn't necessarily 'trust' the Scangauge for fine & totally accurate measurements. That's why I do it the old fashioned way using the actual truck 'Trip A' for the miles on my tank and the gallons used to fill up.

 

Funny you should say that. The miles listed on TRIP A on the truck odometer gets its information from the exact same place as the Scangauge does so the two should match.

As for fuel used and such that's a little different. I pulled my trailer for the first time this past weekend after having the Scangauge for a few months now. It's been spot on what the pump says I put in and what the Scangauge said it was expecting. BUT I've noticed a few problems. If I don't fill up a 3/4 of a tank and say fill up at 1/4-1/2 tank then it's off by .2-.4 gallons. When I pulled my trailer as well it messed up the readings. It was off by .5-.7 gallons after pulling and filling up at 1/2 tank. Now that I'm back to my normal commute patterns for work it's spot on again. Not sure what makes the difference but I suspect it has to do with how the ECU is reporting usage and such and the Scangauge is more of a pseudo average use vs a real time usage. Makes me wonder how accurate the Gallons Per Hour reading is. Scangauge isn't the problem though because it's simply a display for what the ECU is telling it then it calculates everything based on the information it's recieving.

 

Golly, a whole bunch of posts and the original posters answer still hasn't been answered. I understand your question, and yes you will need something like a scan gauge to figure it out. You need something that can give you instantaneous MPG readings. Unfortunately nobody has done this on here yet, at least it appears that way. Those scangauge things look pretty usefull.

 

When I first got the Scangauge at Christmas, I had one hell of a time trying to get it close to accurate paticularly the DTE and gas-type calculations. I knew about how many miles I'd been getting when the gas light comes on..... and the DTE was WAY off. Well, I was carrying 210lbs of sand in the bed all winter. Not long after I removed the sand from the bed....the scangauge got more accurate.

But yeah...the 'calculated' data isn't gonna be as accurate as the actual data it pulls from the ECU. That's why for every tank of gas I fill up with , I always do a manual MPG calculation.

 

The only way you'll be able to figure it out and get actual readings....

Is put your truck on a dyno (smooth, level, & consistant surface) - put the truck up to gear and set the cruise at 60mph (for example). Run it for a good 10 minutes or longer and figure the gas mileage that way. You could get a *general idea* of mpg using the Scangauage - but even that isn't dead nuts acccurate.

Way too many variables to figure it out any other way....

 

I think the method that you outline will be less accurate then the scangauge. The method you talk about does not take into account wind resistance. Our trucks are not the most aerodynamic vehicles on the road, so there will be significant wind resistance. Which means the motor will have to work harder to achieve the same velocity. With all things considered, I would say the scangauge is the cheapest most accurate way to measure this.

 

+1

Thats why the EPA estimate of mileage is so jacked up when you go to purchase a vehicle. They put it on a dyno and run it at 60mph (which many of us do not drive on the highways), AC off, and with no electronics running. Pretty much they run it at the most ideal conditions. I have yet to see 27mpg on the highways with my I4 PreRunner. They don't even take into account the amount of bird poop or bug splats that mess up your aerodynamics.

 

+1

Yet I belive that this year or next the EPA has to start reporting "real world" MPG on vehicles so the same vehicle in later model years may actually show less MPG than it did the previous year. Sorta like the HP/Torque ratings changed on the Tacoma from the 05 to 06 model year. Same engine, same truck but the testing method changed shows less HP/Torque for the 06. Confused the heck out of a lot of people. I'm sure the MPG thing will confuse people as well.

 

Yeah, now manufacturers are starting to use the SAE (Society of Automotive Engineers) rating method of HP/Torque. This pretty much standardizes all the methods in which to rate an engine so that manufacturers cannot milk their numbers. The EPA really needs to step it up and have numbers that actually represent real world driving. I don't know of anyone who drives in 90degree weather on the highway at 60mph with the windows up and AC off.

 

I've actually seen the opposite thankfully. My truck is now rated 15/18 under the new 'more' accurate EPA ratings. 35K and 3.5 yrs the truck has averaged 18.5, better than the hwy rating.

 

You're expecting accuracy with wind resistance calculated in the data?
But what about all the other variables from truck-to-truck & place to place?
Tire pressure, Tire wear & size, bearings/wear, engine wear, different engine oils, driver characteristics, road surface, inconsistant road surface, air temperature, air filter, humidity, air thickness, traffic, gas irregularities, exhaust irregularities, tranny temperatures, and that's only off the top of my head. I'm sure there's more....

There's no way the scangauge can get *that accurate* along with finding the PERFECT conditions to get the most perfect data.

Splitten hairs here...

 

All other things being equal, there is no way that a dyno run with no wind is going to be as accurate then a calibrated scangauge taking instantaneous measurements. That's just not possible, wind resistance is too much of a factor when figuring "real world" gas mileage.

 

well, to answer your question a little better:
55mph- about 22.5to 24.5 Drafting a semi, about 24- 28
60mph- about 19 to 22.5 Drafting: about 23-28
65mph- about 16.5 to 20 Drafting: about 22.5-24
70mph- about 14-17.5 Drafting: trucks usually dont run this fast around me so i dont have drafting figures for this fast.
these are the typical instant mpg readings i've noticed from my scangauge in my 07 Acc cab 4x4 6 speed 3" lift w/ 265/70R17's. This is almost perfectly FLAT road, any hills and it goes bye bye..... down to like 11-13 mpg on a moderate hill (but still 6th), down to about 13.5 to 17.5 on lesser inclines.

Hope this helped out........

 

Thanks xtreme450, I got me an answer!

While yours is lifted and obviously there are many variables, just seeing the % difference between each speed (and drafting) is great info.

 

This is good info, now I don't have to buy a scan gauge!

 

haha...... MOOCHER!

 

Thanks. This is pretty typical to what I've found, but I've noticed for some reason the cruise, even on almost perfectly flat ground, will knock it down about 2mpg. No idea why, but by not using the cruise and keeping an eye on my instant MPG i've increased my highway trip average mpg by about 1.5 mpg. just shows that driving steady doesn't always yield the best mpg.

 

Hardcase,
The dealer has one last silver Taoma manual left - 08 4x4 2.7 5 spd Access Cab. The mileage you quote cruising at 55 is awesome. Do you think I could get at least 26mpg at 55 mph with the Access Cab? Would really take it easy. Really want this truck but fretting about the gas situation. Thanks.

 

I think what he's trying to say is dyno MPG numbers are as useful as tits on a bull. HP and torque numbers, yes, but when are you EVER going to drive where there's no wind resistance. How accurate would it be if the dyno says your truck gets 40mpg, but once you hit the road bucking head winds you only get 12? The numbers from the dyno would be absolutely useless especially since MPG would decrease as speed (and therefor air resistance) increase.

Oh yeah, and the stock speedo is off by about 3mph on stock tires while a scangauge can be calibrated correctly for stock or larger tires (as is in my case). So the odometer readings aren't very accurate.

 

I know I get very good gas mileage around 30mph in 6th, and then again around 55-60. Forget the exact numbers off the top of my head, but there's a definite drop in MPG between low speed in high gear and 55-60 in high gear. I did get 20mpg though doing 45-80 from NY to PA on a 200 mile trip with several stop lights, stop sign, construction zones, hills, etc. And average 20mpg commuting 30 miles to work do 60-65 most of the way. Usually set the cruise to 63 except for 3 35-45mph sections and a couple stops. Holds steading at 20+mpg at that speed with a few drops for wind gusts or me passing people. I have tried driving slower, but didn't seem to notice a difference.