inaccurate speedometer

[civic_99]

I just purchased a honda jazz vti 02 (auto) and realised as I was driving that the speedometer reading is wrong reading 8-10 kms above what it should be. I found out that it is inaccurate coz i turned the gps on, the gps speedo reading is accurate when I tried in my civic but jazz speedo is reading 50kph when its only 40kph. The jazz is stiill running on stock rims with 185/55/15. My question now is can this be calibrated? and did you guys encounter the same problem with your hondas?

[honda_zivic]

wat gps did u use a fone or gps device?

[Bayani]

That's not necessarily true.

GPS is point-to-point tracking and 'averaging' of speed to gain a value.
The best method is to drive a direct line and at a constant pace. (Cruise control pref.) and measure that against your GPS device.

Also, you'll find that your speedo actually would be reading as a PERCENTAGE higher, not at a constant 10km/h than it should.

For instance, if you travelled at 1km/h, your speedo would not read 11km/h.

Drive at 100km/h, straight, and at a constant. Check it against your GPS to find the variance.

ADR allows for an OVERREADING (Which is what you have) by UPTO 10%. This is NOT PURPOSFULLY built in, but is an ALLOWABLE tolerance by design standards.

Also note that an UNDERREADING (ie: You are travelling at 70km/h, but your speedo says 60km/h) is ILLEGAL. If you are CAUGHT speeding, claiming you did not know you were using a faulty speedo MAY NOT get you off.

Ignorance is unacceptable as a plea in court.
Your car, your responsibility.

Kindly, of course :)

[panda[cRx]]

many hondas read about 4-8% higher than the actual speed being travelled. i've never seen a (stock) honda reading lower than the speed being travelled so you don't need to worry about getting speeding fines

if your car is out and you want it rectified there are certain speedo specialists which can recalibrate it for you, i'm not sure of any in nsw as i'm in melb

[borad]

FWIW, my 2007 Jazz speedo is 2% over. This is distracting as the previous car (non-Honda) was 7% over, so my "margin of error" has been cut.

[civic_99]

I shouldnt be really worrying about speeding fines, thats one advantage. Does anybody know where to get this calibrated? Does auto elec's do it?

[borad]

FWIW, my 2007 Jazz speedo is 2% over. This is distracting as the previous car (non-Honda) was 7% over, so my "margin of error" has been cut.
A light bulb :idea: just (finally) went off in my head -- my dash fuel efficiency readings are also almost 2% over. Gee, what a coincidence :p

[panda[cRx]]

I shouldnt be really worrying about speeding fines, thats one advantage. Does anybody know where to get this calibrated? Does auto elec's do it?

tried having a look for yourself? :wave:

http://www.yellowpages.com.au/search/postCategorySearch.do?headingCode=12831&sortByDetail=true&sortByAlphabetical=false&businessType=speedo&sortByClosestMatch=false&sortByDistance=false&stateId=1&safeLocationClue=nsw&currentLetter=&locationClue=nsw&locationText=New+South+Wales

[Type R Positive]

My Toyota Prado is pretty good. It does 107 on the GPS, doing 110 on the dial.
My Euro on the other hand, is pretty sad. Like 100 on the GPS when doing 110 on the dial.

[Type R Positive]

My question now is can this be calibrated?
Bigger tyres?
I have seen adapters that change your speedo on 4x4's. They are used when going to 33" or 35" tyres instead of the stock 31".

[rossw]

A light bulb :idea: just (finally) went off in my head -- my dash fuel efficiency readings are also almost 2% over. Gee, what a coincidence :p

But your manual fuel consumption calculation is done from the odometer/trip meter, which integrates the same speed signal from the speedometer sender. So your manual calculation is going to be out by the same 2% as your speedo.

Therefore if there is an aditional discrepancy of 2% or so between your manual calculation and the fuel consumption gauge, that's a further error.

Now your odometer has an error of 2% and your fuel consumption gauge has an error of a further 2%. The actual total error isn't 4%, but it's close enough.

[borad]

Oops... but no, the 2% distance error applies evenly to both calculations, so it remains a 2% difference, not 4%.

[rossw]

It's a 2% difference between calculated and gauge, but a 4% difference (roughly) between gauge and reality.

[borad]

But because I'm travelling ~2% less than it says, still only 2% more expensive per time period...