Accurate trip computer?

[Noddy 90]

Just calculated that my trip computer over-reads my mpg by 5%. Is there any way to recalibrate this through the OBD port so that it reads accurately?

[lizzard-t]

No
But you could try resetting all trips and do another test .
It could also be the size of the tyres .tyre pressures, ambient temperature, loads of factors go into thease computer jiggery-pokery, it scrambles up all info and throws it out the other end.
I think myself 5% would be classed as a safe reading if low or high .
But still I'm no expert.
And have certificates on my wall that say I have a merit in talking out my blow hole !

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[Noddy 90]

Hi, lizzard,

Thanks for the reply - this is for miles PER GALLON, though, not mph, so "safe reading" isn't really relevant. It's not something that most people would bother with but I have certificates on my wall both for being anal and having OCD...

[lizzard-t]

There are pills for both available from your local pharmacy.





Yeeeeèeeeehaaaaaaaà!

[Drew]

https://www.caranddriver.com/news/a15369613/why-your-trip-computer-isnt-giving-accurate-mpg-readings-and-how-to-fix-it/

I'm sure even if you try and calculate it yourself, to compensate for inaccuracies on filling you would have to repeat the same technique a number of times and take that average, even then there would be some percentage of error. I know of one forecourt where the operator would adjust his pumps (within legal tolerance) on days when he had a delivery because he claimed the fuel was still hot and greater volume. I don't want to cause any OCD but can we be sure how much fuel we are actually buying when it's disappearing down a black hole into the fuel tank, even the pumps have a degree of tolerance!
I don't think you you could ever be confident of any figures your own or the cars!

[Howy]

As above,weather also affects the forecourt tanks,cold in winter then heat in summer,suppose it also applies to the car's fuel tank.
88mpg Urban!

[Drew]

As above,weather also affects the forecourt tanks,cold in winter then heat in summer,suppose it also applies to the car's fuel tank.
88mpg Urban!

I think I could get more if I take the car upto say 70mph, zero the trip and simultaneously lift off the accelerator and coast to a stop. If I did that down a big hill, who knows.
On a point of interest, or not as the case may be, when I was a kid my dad used to do the same routine with every car he bought (just for fun). There's a hill hear us that he used to crest at 60mph, knock the car out of gear and coast as far as it would go. I first remember him doing it in an Austin Cambridge estate, then a Maxi, a Princess, Fiat 132, Ford Granada etc. I think the Maxi was the winner about 2 1/2 miles.

[MattG]

Or just use an app

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[Noddy 90]

That app looks good! I used to have a similar one but I soon got bored of entering all the details in. I just want an accurate trip computer, really. I appreciate everyone's points about the number of variability factors...

[lizzard-t]

I think the accuracy of anything is reliant on the person who programmed it .
fir all we know that person could of been smoking a Jamaican woodbine whilst trolling tinder for his or hers next "pick-up ".
with me I'm an airy fairy kind of guy and accept things are not as accurate as they may claim to be .i look at life with positivity and caution.
all I know is that my wife is a woman because I've been inside her knickers !
and that the trip computer on my car is on Drugs !
Hamen .
yes OCD dose effect me in my workaday little world just look .
And it gets worse .





but still that's me ,
we are all different and all being different is what makes us unique and being unique is fantastic
or the world would be boring!

[Humbug]

Could it be that the speedo reading is inaccurate? The calculations on mpg within the car are linked to the speedo which is inaccurate (mine reads 3mph different to GPS at most speeds). The speedo will be telling the fuel gauge that you have gone further than you actually have so will make an incorrect calculation based on that.

[the gas man]

I think the accuracy of anything is reliant on the person who programmed it .
fir all we know that person could of been smoking a Jamaican woodbine whilst trolling tinder for his or hers next "pick-up ".
with me I'm an airy fairy kind of guy and accept things are not as accurate as they may claim to be .i look at life with positivity and caution.
all I know is that my wife is a woman because I've been inside her knickers !
and that the trip computer on my car is on Drugs !
Hamen .
yes OCD dose effect me in my workaday little world just look .
And it gets worse .





but still that's me ,
we are all different and all being different is what makes us unique and being unique is fantastic
or the world would be boring!

What a professional job, great installation

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[Humbug]

In my role working for the NHBC, that's a class installation Mr Lizzard-T