Calibrate the speedo - Page 2

TTDegs · 5th April 2008, 00:16

Quote:

Originally Posted by ctrdaveg

Surely sat-nav speeds are not that accurate ??

I think they probably are...
How Sat Nav Works
TomTom/Sat Nav GPS Spped Accuracy - Page 2 - Volvo Performance Club UK Forums

Miggins · 4th May 2008, 17:39

I don't believe the speedometer on the Civic (mine at least) is simply out by a percentage through the range, as was the case with mechanical speedometers in 'olden' days.

Mechanical speedometers used to fall within the legal requirement of 10% up to 70mph and then go haywire at any speed over this (the UK national limit).

My Civic is out by +3mph (seems more sometimes) at 30mph and +4mph at 40mph. At higher speeds it doesn't go out by more than 4mph - this is also the case at speeds above 70mph.....mmmmm. So will a pulse modifier work accurately if the input is not linear? Logic says not unless you can input a non linear variable compensation.

BTW: All speeds were compared with 2 GPS units and another vehicle (SEAT Alhambra) to validate the GPS readings as well as the useless roadside speed indicators!!. All done at steady speeds to ensure the GPS had time to recalculate etc.

p64 · 5th May 2008, 21:44

I think it is the sofware that modifies the speed indication, since mine also deviates about 6 km/h at speeds above 50 km/h up to 160 (did not bother to go higher). Speedo healer is not the right solution. You would be surprised that the odo is quite accurate, within 2%, imo because of the tyre diameter change. So, again, the speedo is manipulated, shame.

andrej

Big_AL · 7th May 2008, 19:57

Think I am loosing the will to live on this one.......Every time I drive past one of those flashing radar posts which reads your speed....usually I am 5 mph high.......so what. When I drive by the gatso's at the wrong speed, let's hope this bit of built in buffer saves me a ticket. Pottsy, I am well impressed that you even contemplated working out how to do this.......

philosoma · 7th May 2008, 20:15

I still have not fitted mine yet, is tricky to get to. Anyone with petrol engine fitted one yet?

bbalas74 · 12th July 2008, 10:49

I cant believe this could not be done more easily, without so many nuts and bolts! Just by fiddling with the car software should do the trick!

4th May 2008, 17:39	#22 (permalink)
Miggins Enthusiastic Supporter Magic Rear Seat Join Date: 25th August 2006 Location: The Twilight Zone Posts: 529 Thanks: 0 Thanked 0 Times in 0 Posts iTrader: (0)	Linear % Error I don't believe the speedometer on the Civic (mine at least) is simply out by a percentage through the range, as was the case with mechanical speedometers in 'olden' days. Mechanical speedometers used to fall within the legal requirement of 10% up to 70mph and then go haywire at any speed over this (the UK national limit). My Civic is out by +3mph (seems more sometimes) at 30mph and +4mph at 40mph. At higher speeds it doesn't go out by more than 4mph - this is also the case at speeds above 70mph.....mmmmm. So will a pulse modifier work accurately if the input is not linear? Logic says not unless you can input a non linear variable compensation. BTW: All speeds were compared with 2 GPS units and another vehicle (SEAT Alhambra) to validate the GPS readings as well as the useless roadside speed indicators!!. All done at steady speeds to ensure the GPS had time to recalculate etc.

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This thread is about: Calibrate the speedo, it's in How To at the Honda Civic forum Civinfo; Originally Posted by ctrdaveg Surely sat-nav speeds are not that accurate ?? I think they probably are... How Sat Nav Works TomTom/Sat Nav GPS Spped ...

5th May 2008, 21:44	#23 (permalink)
p64 Ezermester Wheelnut Join Date: 3rd July 2007 Location: MS Posts: 68 Thanks: 0 Thanked 1 Time in 1 Post iTrader: (0)	I think it is the sofware that modifies the speed indication, since mine also deviates about 6 km/h at speeds above 50 km/h up to 160 (did not bother to go higher). Speedo healer is not the right solution. You would be surprised that the odo is quite accurate, within 2%, imo because of the tyre diameter change. So, again, the speedo is manipulated, shame. andrej

7th May 2008, 19:57	#24 (permalink)
Big_AL TYPE_R GT in NHB Valve Cap Join Date: 18th March 2008 Location: Ayrshire Posts: 34 Thanks: 0 Thanked 0 Times in 0 Posts iTrader: (0)	Think I am loosing the will to live on this one.......Every time I drive past one of those flashing radar posts which reads your speed....usually I am 5 mph high.......so what. When I drive by the gatso's at the wrong speed, let's hope this bit of built in buffer saves me a ticket. Pottsy, I am well impressed that you even contemplated working out how to do this.......

7th May 2008, 20:15	#25 (permalink)
philosoma Wheelnut Join Date: 23rd March 2007 Location: England Posts: 79 Thanks: 0 Thanked 1 Time in 1 Post iTrader: (0)	I still have not fitted mine yet, is tricky to get to. Anyone with petrol engine fitted one yet?

12th July 2008, 10:49	#26 (permalink)
bbalas74 Valve Cap Join Date: 13th January 2008 Location: Basel, CH Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts iTrader: (0)	I cant believe this could not be done more easily, without so many nuts and bolts! Just by fiddling with the car software should do the trick!