Speedo Out

[DavoXT]

While driving to the local town (400km round trip) I reset the avg speed on the computor and it read 5 to 7kph out compaired to my speedo.

Sorry officer that should read 10-20km over not 20-30km, I wonder which is correct and how can I correct it so both read the same.

[Adam]

I don't think theres anything wrong with the trip computer it shows AVERAGE SPEED not the speed you are currently doing. So because you slow down for traffic, changing speed limits, traffic signs etc it gives a lower average because these slower speeds have been calculated aswell. To get the speed to be the same you would need to reset the trip computer at speed and maintain that speed with no decreases for a period of time.

I do about 60% town 40% highway driving and my average speed hasn't gone above 40kmh because of the slow town driving even though I've travelled at 110kmh for 2 hours constantly a few times.

[F6 RAPID]

Dude, what I think Davo means is this, drive along at 100km/hr as best you can and put your cruise on. Then scroll through your trip meter until you find your average km/hr and then reset it while sitting on 100 and have a look at your average speed and you will see it will most likely say 96 ish km/hr. By doing this, it negates all that stop-start - obviously.

This is something I noticed also.

[DavoXT]

Yer I no its the avg speed but if you reset while moving it will give you your current speed.

So it should read the same as the speedo, like police mode.

[KrasH]

I wouldn't be suprised if the speed is a little "off". My pulsar SSS speedo is off by a few km's. Last summer there were those "your true speed" trailers around the place and basically, the trailer said true speed was 80km/h, my car speedo read about 82-83km/h. I remember the XF was off a bit aswell. It used to get serviced at a Dyno place, and the sheet they'd give had speedo reading 100km/h, real speed 96km/h. But I must say that the funniest must be the NSW police WRX's. They were apparently out by upto 18km/h or thereabouts at 120km/h or 130km/h on speedo I think (speedo read say 130km/h, you were actually going 110km/h or something). Had something to do with the tyre choice or something along those lines.

[DallasQLD]

I know the speedo in mine reads fast by 5KPH at 100. On my digital speedo I get 100 KPH and on the dial I get 105

Checked it coming intp Victoria on that overhead radar tester. Digital exact speedo out by 5KPH

[NT TURBO]

  DallasQLD said:

I know the speedo in mine reads fast by 5KPH at 100. On my digital speedo I get 100 KPH and on the dial I get 105

Checked it coming intp Victoria on that overhead radar tester. Digital exact speedo out by 5KPH

Yep and at 230 it reads just over 240! lol

[plonky]

The Australian standard on speedometer accuracy is 10% (remember that when you take a Victorian speed camera ticket to Court)

There is an art to maintaining a constant speed to check the accuracy of a speedometer. There is only one place in Sydney (Injection Perfection) that places the car on a dynometer and calibrates the digital (additional) speedo for the HWP cars.

You will generally find that the digital speedometer on modern cars is accurate to within 3%. The trouble you may have when trying to estimate whether your analogue speedo is accurate is parallex error when looking at the needle and digits and the fact that normal speedometers are only calibrated in 5kmh increments as opposed to 2kmh increments on HWP vehicles.

[dankman]

  DallasQLD said:

I know the speedo in mine reads fast by 5KPH at 100. On my digital speedo I get 100 KPH and on the dial I get 105

Checked it coming intp Victoria on that overhead radar tester. Digital exact speedo out by 5KPH

If that's the one just past wodonga heading south, I've noticed no matter what car I take under that thing, I'm always out by 5 kp/h

Usually it says I'm going slower than whats on the speedo.

All of the newer falcons we have here at work show the same reading, although the holdens seem to be almost right.

Revenue raising? or is Ford putting out their cars 5 kp/h slower?

Or is that sign just f**ked?

[dankman]

  plonky said:

The Australian standard on speedometer accuracy is 10% (remember that when you take a Victorian speed camera ticket to Court)

There is an art to maintaining a constant speed to check the accuracy of a speedometer. There is only one place in Sydney (Injection Perfection) that places the car on a dynometer and calibrates the digital (additional) speedo for the HWP cars.

You will generally find that the digital speedometer on modern cars is accurate to within 3%. The trouble you may have when trying to estimate whether your analogue speedo is accurate is parallex error when looking at the needle and digits and the fact that normal speedometers are only calibrated in 5kmh increments as opposed to 2kmh increments on HWP vehicles.

ahhh that could be it

Thanks plonky