So I have the Edge and I was wondering


Should I trust the Average MPG shown on my edge, or on my information spot on my dash?

My dash has been telling me like 10mpg Lately, while my Edge has stayed up around 12 MPG...

I have 33" Toyo Mudders on, and I have the "Custom" options set to include my tires,

Should I trust my Edge or my Cluster?

 

my truck is pretty stock and im getting about 17MPG on the highway and 15 in the city...

 

I got a 6 inch lift and 35's and i was getting 14 with my edge AMPG and around 13.5 on my dash. Damn, 10 that sucks.

 

The Edge is pretty close on ampg.

 

mine is wayyyy off it reads 16-17 on a long trip and i stop to filler up and do the math and is 22-23 so i dont trust it

 

I checked it a few times and was off by .5 gallons. Unless your beatting on your truck it shouldnt be off more then that.

 

Alright, Cool

My dash one has been real low, and I wasjust wondering whether to trust my Edge or my Dash....

Since they have like a 2 mpg difference

Im gonn go ahead and trust the edge

 

Computers don't lie.
I use the miles travelled & gallons used method.

 

me too

 

Lots of work :P

 

Neither. Do fill ups. Divide the number of miles driven on a tank of gas by the number of gallons it takes to fill up again. That is the only accurate way.

 

This is exactly what I did on my truck before I installed an Edge. Surprise! The MPG shown by the computer exactly matched the MI/Gal calculation when I filled the tank.

However, when I installed the Edge, it told me I should use 2559 mm for the tire circumference since I have 275/65/18 tires. Then, I find Bill (ASEMechanic) recommends reducing that by 5% for tire "squish". So, I did the more primitive thing - I measured a revolution. For my tires, I traveled approx 2500 mm in one revolution (+/- 10 mm). This worked out to about 2.3% for "squish" (at 40 psi). Now, if your tires are not inflated this high, a higher "squish" factor is needed. If inflated more, perhaps, a lower factor.

So, If you're going to try to program your programmer, I suggest you measure the travel. Since the speedometer is controlled by the computer, and since the programmer resets the computer, I think this is the only (semi) accurate way to go. You're not going to get any validation from the speedo since it is usiing your programmed tire circumference to show you miles traveled - and miles traveled by gallons used just shows this (possibly fictional) value.

I guess an easy test would be to set your tire circumference to the highest value shown by the programmer and then see if it still agreed with the mi/gal calculation. (Maybe this explains how some folks seem to get 21-23 mpg in this beast).

Bill, if you see this, any thoughts?

- Jack

 

OK folks - Here's what you do:

1. Use a GPS to verify your speed. One of the other members did just that. Should be accurate to +/- 1 or 2 mph depending on how far you go and how steady you keep your indicated "speedo" speed.

2. The more primitive way: Set your speed control to 60 mph (everyone has one of those, right)? and travel a distance of at least 5 mi using highway milepost markers. (More would be better and it would be perfect if you could do this on flat ground - pay no attention to all the faster drivers giving you the "You're number one!" finger as you dawdle along this course). If you go "exactly" five miles in five minutes, your speedo (and tire circumference) are dead on. If, however, you find you travel those 5 miles (using the highway markers) and it takes you about 5 min, 30 sec, then you are only doing about 54.5 mph - but your speedo "thinks" you are going faster. If you pass the 5 mile milepost in say, But, if you do the five mile course in about 4 min, 30 sec, then your speedo is way slow - your're actually traveling about 66.7 mph.

And, if your speedo is "fast", it thinks you have gone farther than you really have. If it is "slow", it doesn't credit you with the miles you have really driven (and , you might be a "ticket magnet").

You all can chime in with your thoughts if you'd like.

- Jack

 

I checked my speedometer with a GPS and there was 2 mph difference. The speedometer was faster.

 

Cool -

So, your speedo (and computer) are telling you that you've covered more distance than you really have done. So, if you use the miles driven (recorded by your truck) and divide that by the gallons of gas you burn, you come out with a "high" mpg figure - which is a lie (it's still a gas guzzler - just like mine). If you are 2 mph higher at 60 mph, and you calculate about 16.5 mpg, you're really getting about 16 mpg.

But if your speedo says your're 2 mph slow and have covered fewer miles than you really did do, then, in addition to being a potential ticket magnet, you are more economical than you think you are. You'd might calculate mileage at about 15.5 mpg, but you would actually be getting 16.

A 2 mph error is really significant!

Sorry, I meant to put all this in the last post, but got stopped for dinner. And, there's an incomplete thought in the last post I wish I had deleted before I put it up.

BTW - I'm not unhappy with my truck, it pulls my travel trailer like a dream and that's why I bought it. You have to pay for performance somewhere.

- Jack