MPG loss at idle WTF?????

kdub627

kdub627

Member
Ok I just went and got new tires today. I got some Toyo Open Country H/T (265/70/17). Well my MPG on the computer is saying Im getting 13MPG!!!!! I normally get around 19 MPG in city.

The weirdest thing is that while a sit at idle my computer drops .3 MPG every 10 seconds. Does this mean there is a problem with my sensors? Should I reset my computer by unplugging the battery?

I know I was going to lose a a mile or so a gallon with the bigger tire but 6 is ridiculous!
 
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kdub627 said:
Ok I just went and got new tires today. I got some Toyo Open Country H/T (265/70/17). Well my MPG on the computer is saying Im getting 13MPG!!!!! I normally get around 19 MPG in city.

The weirdest thing is that while a sit at idle my computer drops .3 MPG every 10 seconds. Does this mean there is a problem with my sensors? Should I reset my computer by unplugging the battery?

I know I was going to lose a a mile or so a gallon with the bigger tire but 6 is ridiculous!
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Can't answer the tire question, but I also expirience MPG loss at idle (as shown by the computer) at roughly the same rate you are describing. No clue why.
 
Did your computer get reset? If it did then it might take a while of driving to level back out. But, .3 every 10 seconds.....that's kinda extreme. Mine might drop .1 every minute or so.
 
JCR said:
Did your computer get reset? If it did then it might take a while of driving to level back out. But, .3 every 10 seconds.....that's kinda extreme. Mine might drop .1 every minute or so.
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Computer was not reset and yes it is quite weird how it drops like that, but as soon as I begin to move again it goes back up.
 
I would think since you are just idling and not moving, you are getting 0 MPG and that is why it is screwing up your average. Just my opinion,
 
4Runnewbie said:
I would think since you are just idling and not moving, you are getting 0 MPG and that is why it is screwing up your average. Just my opinion,
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:iagree: and less data the avg mpg meter has available the quicker the mpg drops while idling. If it's been weeks since you reset the avg mpg it'll take a long time to drop the average while idling. If the tire tech was punching buttons (reset the avg mpg meter) on his test drive there may not be much data in there.


I would add that the mpg meter will be lower than the previous 19. HOWEVER it will be closer to accurate. It's probably a 2mpg optimistic now (original tires) and it'll be .5 to 1 optimistic when all is said and done. To figure that out you have to hand calculate mpg after learning the correction for factor odometer error. Your odo probably under-reports about 3.5-4%.



How do you like the Toyo's so far?
:cheers:
 
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Tell us how you like those tires and what you had before (and how they compare).

I'm sure they are gripper everywhere but how much noisier? Is the ride a lot rougher? What size did you move from? Did you also get a new spare and did it fit easily?
 
Flyer said:
Tell us how you like those tires and what you had before (and how they compare).

I'm sure they are gripper everywhere but how much noisier? Is the ride a lot rougher? What size did you move from? Did you also get a new spare and did it fit easily?
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Well we have had no rain here in New Orleans since the day I got them but as of right now I like them. I can notice a slight bit of roar at 50-55 but you would have to have your A/C and radio off to barely notice it, but at any other speed it is quieter then the stock Dunflaps I had. The ride is softer and smoother as well.

I personally can tell a notice in height difference just from the tires. I do plan on adding the daystar 2.5/1.5 within the next month.


Here she is all cleaned up
DSC00593.jpg~original

Also I never got a spare right now because the tire has yet to be used thats there, so I figured it can stay and save some cash.
 
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Nice. Mine is also white with tinted windows. So I guess your spare is a mismatched size? Anyway, thanks for the info on those tires. I'm torn between those and the Hankook Dynapro ATMs.
 
Flyer said:
Nice. Mine is also white with tinted windows. So I guess your spare is a mismatched size? Anyway, thanks for the info on those tires. I'm torn between those and the Hankook Dynapro ATMs.
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yea my spare is a 265/65/17, oh well...:cry2:
 
If you know you are going to be sitting for a while try shutting off the engine. Anytime the engine is running it is consuming fuel. Also, when the engine is running the mpg meter is running - its looking for two things-miles and gallons consumed. If your not moving your not adding up miles.
 
gm350reratliff said:
If you know you are going to be sitting for a while try shutting off the engine. Anytime the engine is running it is consuming fuel. Also, when the engine is running the mpg meter is running - its looking for two things-miles and gallons consumed. If your not moving your not adding up miles.
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yea but im talking about it dropping while at a red light or traffic. I have NEVER had my mpg computer go below 17mpg and now after the tire change its showing 11-14 mpg. My average MPG before the tires was 18.8 MPG.

Somethings up...
 
I reset mine every fill up, and mine does the same thing, it's not "really" that low though, it's a relatively "dumb" algorithm that sees you are going zero miles yet are using gas so the number nose dives.

fwiw, my on board avg. MPG computer is a steady 15% optimistic vs. my hand calculations. (V8)
 
Let's see.... engine running (using fuel), sitting still (NOT going anywhere) and you wonder why your average MILES PER GALLON is dropping. And the fewer the # of data points (fewer miles since the last reset), the greater the magnitude of the change from something as benign as idling.

I'll even bet that you're the type of person that'll hit "RESET" going downhill and insist he's getting 50+ MPG.

Learning how things work is key to understanding what the information from them means.
 
Nuke said:
Let's see.... engine running (using fuel), sitting still (NOT going anywhere) and you wonder why your average MILES PER GALLON is dropping. And the fewer the # of data points (fewer miles since the last reset), the greater the magnitude of the change from something as benign as idling.

I'll even bet that you're the type of person that'll hit "RESET" going downhill and insist he's getting 50+ MPG.

Learning how things work is key to understanding what the information from them means.
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Hey thanks for the sarcasm, but not really. If you would read the first damn post you realize this has just come about for the first time after I got new tires. Thus meaning that beforehand this was never an issue. Normally the **** doesnt move jackass because its not reading any rotation of the tire which means it stays at a constant 18.8 for me BEFORE THE NEW TIRES!!!!

and you sure figured me out about going downhill and all. Actually I reset it and floor it as fast as I can and when I stop I put it in neutral and redline it.

Thanks for the help:thanks:









borat-not-jb.jpg~original
 
Your inability to grasp how the on-board function is exasperated by your last post. Sitting at a dead stop WILL cause (and is EXPECTED to cause) the on-board average MPG reading to slowly drop; the rate at which it drops is related to how many miles you've clocked since the last reset. For those that rarely if ever reset it, then it will probably NOT change much if at all but then, it won't indicate other recent impacts to your fuel mileage either.

Who's the jackass now, ****head? And you're welcome.

BTW, I find it interesting that about 4 or 5 other folks have told you the same thing as I have and you STILL don't get it.
 
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KDUB, any resolution to this? After a fill up what does the range on your computer show?

I'm asking b/c my range at full tank is 325 miles where it used to be 380-400. I know I'll never get the max stated range from edmunds.com for the v6, "Range in miles (cty/hwy): 368.0/483.0 mi" So I know for a fact also that something is wrong.

My hand calcs are also showing about 14mpg with mixed city/hwy driving.
 
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