How accurate is the trip computer?

T

testrider

Member
HI all,

I just bought a 2003 4Runner SR5 (V8) 2 days ago and I haven't finished my 1st tank of gas. I'm wondering how accurate is the trip computer? Especially the MPG display? Is it pretty close comparing to the actual miles driven divided by the number of gallons filled? How about the average MPH display?

I really like it if it works accurately.

Thanks.

-Mike-
 
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I just filled up - computer said 19.2 mpg, reality was 17.1. I've reset it to see if it makes any difference.

Can't quite figure out the range, because it's not gallons left in the tank times average mpg -- it's quite a bit less than that.
 
Thanks John,

Thanks for the info. Ok, so the MPG is useless then. I was able to check that the average MPH display was pretty accurate by calculating distance/time myself when I go to work. I wonder why MPG is so off? It can be calculated easily by the onboard computer as gasoline consumed is just a sum of all injector 'ON' time multiplied by the injector volume per unit time.
Fuel injectors are either ON or OFF and the fuel spray is constant.

-Mike-
 
Who knows? But I've seen in other forums, too, where it's way off. Let's see if the reset does any good, although I'm not optimistic that it will. I just don't drive much anymore (work from home) so it may take a while to see.
 
Wow, that's off a lot! I was just trusting the computer this whole time. I'll start doing my own measurements!
 
Let us know how your measurements go.

Mine are pretty consistent when I figure mpg -- fill up the tank, then divide number of miles driven by number of gallons to fill up. Since I top off the tank, it's pretty close, although not totally scientific.

By the way, on all cars I use trip odometer A for miles driven per tank. It's a good way to cross-check the fuel gauge to make sure everything is OK.
 
jharris2 said:
Let us know how your measurements go.

Mine are pretty consistent when I figure mpg -- fill up the tank, then divide number of miles driven by number of gallons to fill up. Since I top off the tank, it's pretty close, although not totally scientific.

By the way, on all cars I use trip odometer A for miles driven per tank. It's a good way to cross-check the fuel gauge to make sure everything is OK.
Click to expand...

Divide # of miles driven by the # of gallons filled, that's at least 99% accurate. Did you say this number is close to what was shown on your trip computer? How close?
=Mike-
 
Wasn't close at all. The computer said 19.2 mpg, my calculation was 17.1. That's an error of almost 11%. :confused:

To be clear, I'm very careful to fill up the same way every time to minimize variation in mpg calculations.
 
Hey guys, I split off the discussion on the front license plate bracket mod into a new thread located HERE
 
Neech: Nice pic :) Law enforcement? or something else?

Guys/Gals: the trip computer calculates the mpg differently than the basic miles / gallons method. If you do some field testing try keeping the car idle for 15 min and watch the trip computer's mpg go down... Somehow it calculates the time it's idle too and factor that in but either way it's wrong...

It's incorrect in a significant way that the only thing I use is the outside temp guage... hehe :) sometimes less is better!

lance
 
When idling, the mpg keeps going down is correct. When you're idling, you are basically doing 0 mpg and therefore the average keeps going down. Nothing wrong there.

The "average MPH" seemed to be very accurate (total miles traveled / engine running time).
 
testrider:

yes it should go down but not significantly that you will notice it.

either way the trip computer is inaccurate and only should be used as a means of getting a general idea of what you wish it to be :) because if you calculate the real mpg using miles used divided by gallons consumed, you'll be in for one big shock :)

I've given up on the trip computer and only rely on the clock and the temp guage that's shown. I sometimes use the # of miles left just to get a good idea of how far I can go so I can plan my gas runs but other than that, don't rely too heavily on the trip computer has it's not accurate.

Other than that, the 4runner is a very very well made rig :) No complaints here except for the loss in height!!!! but dang the v8 more than makes up for it so i'm a happy camper!

Just take good care of your 4runner and u know u'll be driving it for years to come!! woo hoo

Lance
 
Lance, like you, I only use the trip computer for the clock and thermometer. Good thing it was standard equipment, too -- if we'd have paid extra for the computer, we'd all be complaining about being ripped off instead!
 
JHarris:

Indeed, I'd be b*tching about it like crazy! :)

well then again I'm already complaining about the loss in height and the darn POS tires.... geez... and I bought a $30k rig to only find out I gotta upgrade! hehe

Not like it was gonna stay stock for long anyway! hehe

Stock just doesn't cut it anymore!!! upgrades, upgrades, upgrades... when will it ever end?

Lance
 
Good Times said:
Stock just doesn't cut it anymore!!! upgrades, upgrades, upgrades... when will it ever end?
Click to expand...

Don't know - my wife will be wondering why we got this one if all I do is make changes!! Need to add fog lights, better sound, etc. Next is a VIN etch on all 11 pieces of glass.

But I'm not going to take this thread off course again.... ;)
 
Good Times said:
Neech: Nice pic :) Law enforcement? or something else?
Click to expand...
Acutally, Counter-Strike, online game. I love it!! :D

I hear ya on the tires! I'll post my milage soon, half way there now. I found a place where there's a mesured mile so I'll throw that true value in for fun now that I have the bigger tires.
 
CS ehe? dang I didn't know people still play that game!!! I used to play myself but that must have been atleast 3-4 yrs ago.... wow!
 
Ok, just filled up my 1st tank last night and by calculation it was 18.8 mpg (mostly stop-and-go traffic here in Los Angeles) and the trip computer said 21.5 mpg.

-Mike-

2003 4Runner SR5 4.7L V8
 
mike that sounds about right.... wow u actually got the computer to read 21+!?!?!? now that's nice :) Mine usually says 16-18 and 18 if i'm really really lucky too...

dang i gotta let off the gas!!!
 
Good Times,

I reset the trip computer's MPG after filling up. The day after I picked it up from the dealer, I filled it up and reset the MPG and that's what it read but it was way off so it's useless...

=Mike=
 
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