Battery Disconnect

[NeilSmith]

are you using the display to determine the mpg ? I never do. First of all its not correct because of the larger tires, and then Id rather just do the math instead of relying on a computer display.

[Sal-XK]

The computer display and your math would be corrupt because the odometer mileage is off do to the tires correct?

[NeilSmith]

i dont use the odometer neither, i use gps.

[Sal-XK]

i dont use the odometer neither, i use gps.

I used the GPS to get my spedo error so I can responsibly get some what of an accurate MPG. I'm running about 14.2 right now country hilly driving.

[NeilSmith]

it just sounds funny to me that if the computer knew what it was doing then it would automatically detect that you changed the plugs and you wouldnt have to unhook the battery to reset the system. im old fashioned , i guess.

[Matt]

i dont use the odometer neither, i use gps.

GPS doesn't account for altitude changes. If you live in a flat area it's not bad.

it just sounds funny to me that if the computer knew what it was doing then it would automatically detect that you changed the plugs and you wouldnt have to unhook the battery to reset the system. im old fashioned , i guess.

The computer doesn't detect spark plug changes at all, not even unhooked. That just puts the computer back in to "learn" mode all over again and resets all of the sensors. If there are any changes that computer should make due to the plug change then it would eventually optimize itself, but it will take some time... you just force it to do it sooner by disconnecting the battery.

[Sal-XK]

GPS doesn't account for altitude changes. If you live in a flat area it's not bad.

Depends on what brand and model you're using. I use a hand held for land navigation that does take hills and stuff into consideration as it tracks you mileage. I don't know to much about the ones mounted in cars though. I have to wedge it in the window sometimes I have to hold it in the window I hardly if ever use the nav unit installed in my jeep.

[jay in nb]

GPS doesn't account for altitude changes. If you live in a flat area it's not bad.



The computer doesn't detect spark plug changes at all, not even unhooked. That just puts the computer back in to "learn" mode all over again and resets all of the sensors. If there are any changes that computer should make due to the plug change then it would eventually optimize itself, but it will take some time... you just force it to do it sooner by disconnecting the battery.

Thats is the reason I disconnected the bty, after 4 days of driving and filling up twice due to the amount of driving I did, I saw no change at all ( Computer or how many K's I was getting per tank) I don't completely trust the computer with how much MPG i'm getting but when the number didn't change I though I'd try it and it seems to work, same drive after disconnecting I got almost 100K's more. Now that fishing is open I will be going to the cabin every weekend and I'll see how much k's I am still getting to a full tank.
While looking at the MPG is not a modivational poster it doesn't matter when I pass 3 stuck Toyotas stuck, yes 3 and just drive around them to get to my fishing holes, it worth every $/gallon

[Matt]

I use my display.

First off its not thrown off any more or less than the odometer is by tires.... and you're using the odometer to determine miles right?
Second, the engines computer is MUCH more accurate at determining the relationship between fuel consumed and miles driven. The resolution for fuel consumption in the engine is very refined..... however the "trigger" for gas stations are not. Just because you fill up and the gas pump turns off at 16.56 gallons does not mean that you have used 16.56 gallons. So dividing "miles driven" by amount to fill up is actually much more inaccurate. Some gas pumps are more sensitive than others so they'll stop sooner and therefore your "calculated" MPG will be higher than actual.

The computer however is very consistent and there gives the best tank-to-tank comparison of gas mileage changes.

That's how I look at it anyways.

[Matt]

You can easily adjust for new tire sizes by taking the MPG (calculated or computer) and multiply it by (new tire diameter / old tire diameter).