GolfGTIforum.co.uk
Model specific boards => Golf mk5 => Topic started by: zaker on 27 February 2007, 17:38
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Excactly how accurate are golf speedos ? I have a Talex speed camera detecter which also gives a mph readout. At 90 mph (speedo reading) the talex is showing 82mph. Of course it could be the Talex which is inacurate ?? but i had it in my TT and the discrepency was only about 3 or 4 mph.
Has anyone else experienced this ?
Cheers Z
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GPS speedos are only really accurate on long, straight flat roads.
I was under the impression that VAG speedos were pretty accurate. My S4 is only 1mph out at 70mph. Maybe your speedo has been incorrectly coded/calibrated.
Is your car an import??
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GPS speedos are only really accurate on long, straight flat roads.
I was under the impression that VAG speedos were pretty accurate. My S4 is only 1mph out at 70mph. Maybe your speedo has been incorrectly coded/calibrated.
Is your car an import??
No its not an import. Think i might let the dealer have a look
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My 06 Mk5 GTI and 56 Mk5 R32 were exactly the same as yours - speedo reading starts to lose accuracy past 40mph and the figures you've given tally with what I found when I compared it with the speed on my tomtom. I tested my wifes Mk4 1.8T GTI with the tomtom and the readings matched to 1mph so that car is fine. There is definitely an error there with the Mk5's - and before anyone points out the error on a gps signal, htats true that there is one but it is constant (introduced by the Americans) and therefore does not affect speed measurements. On a positive note, its saved me from a few speeding tickets and points :grin:
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I have a TomTom Go and a Road Angel, and if I use them together at say 73 mph they both read the same, but the car reads 80 MPH, I read on an American forum that VW issued a service bulletin for this problem, however my dealer knew nothing of it.
Corrected..
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I thought 10% was a generally accepted difference between actual and speedo readings?
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I treat it is a nice safety measure!
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I have a TomTom Go and a Road Angel, and if I use them together at say 80 mph they both read the same, but the car reads 73 MPH, I read on an American forum that VW issued a service bulletin for this problem, however my dealer knew nothing of it.
So are you saying that the speedo reads 73 when you are actually doing 80 - surely this is the wrong way round? :shocked:
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I have a TomTom Go and a Road Angel, and if I use them together at say 80 mph they both read the same, but the car reads 73 MPH, I read on an American forum that VW issued a service bulletin for this problem, however my dealer knew nothing of it.
So are you saying that the speedo reads 73 when you are actually doing 80 - surely this is the wrong way round? :shocked:
Laney, your right, I got it the wrong way round, speed reads 80 and Sat Nav- Road Angel 73 mph :rolleyes:
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The US TSB can be found at http://vonx.homeip.net:81/~twb/carwork/speedo/vw.tb.90-06-01.pdf
There's also a trick to show your speed on the climate temp display (I suspect people already know this).
Press Econ and Up arrow (top right of the four) at the same time
Use the left dial to set the left figure to 19
Use the middle dial (fan) to set the left figure to 19.1
Read your speed in the right temp display
Click Econ to reset
There are some other readings you can get:
* 1.0 : Temp as read by sensor in middle fan speed knob
* 1.4 : light intensity falling on same sensor
* 4.0 : Outside temp - front bumper
* 4.1 : Outside temp - roof?
* 15.0 : Oil temp
* 19.0 : Uncorrected speed (Kmh)
* 19.1 : Uncorrected speed (Mph)
* 19.2 : Coolant temp
* 19.3 : Revs
* 19.4 : Oil pressure?
* 25.0 : Voltage
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I have a TomTom Go and a Road Angel, and if I use them together at say 80 mph they both read the same, but the car reads 73 MPH, I read on an American forum that VW issued a service bulletin for this problem, however my dealer knew nothing of it.
So are you saying that the speedo reads 73 when you are actually doing 80 - surely this is the wrong way round? :shocked:
Laney, your right, I got it the wrong way round, speed reads 80 and Sat Nav- Road Angel 73 mph :rolleyes:
I was getting concerned that I wouldn't be able to open my front door when I get home tonight because of the mountain of speeding notices on my door mat :grin:
At least it builds a bit of safety net in I suppose - a poor show from VW though IMO :angry:
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More info/hack here:
http://forums.vwvortex.com/zerothread?id=2886728
Cass
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At least it builds a bit of safety net in I suppose - a poor show from VW though IMO :angry:
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:huh: Do VW actually make the speedoes, i doubt it.
Not exactly a major life affecting issue your speedo being a few mph out, as long as it is on the low side :smiley:
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There's also a trick to show your speed on the climate temp display (I suspect people already know this).
I tried this on my way home from work last night - 70 on the speedo equated to 63 on the temp display :angry:
Does anyone know if the temp display is likely to be more accurate? Whats the difference between how the speeds are measured?
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I tried this on my way home from work last night - 70 on the speedo equated to 63 on the temp display :angry:
That sounds about right :grin:
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Does anyone know if the temp display is likely to be more accurate? Whats the difference between how the speeds are measured?
My educated guess would hedge towards the climate display being more accurate, simply because the speedo is an electro/mechanical component.
They both get their speed "info" from the same source, namely the ABS wheel speed sensors. The signal is then "converted" into an mph/kmh figure for display on the climate and speedo by one of the cars ECUs. That is why the raw data can be adapted on the VAG-COM, or at the dealer.
EDIT corrected my numpty error: By law, speedos can never under-read, but can over-read by up to 10%, so a genuine 70mph could be displayed on the speedo anywhere between 70-77mph.
My S4 seems to be very accurate, at an indcated 80, using cruise on arrow straight roads, GPS displays 79! :smug:
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Does anyone know if the temp display is likely to be more accurate? Whats the difference between how the speeds are measured?
My educated guess would hedge towards the climate display being more accurate, simply because the speedo is an electro/mechanical component.
They both get their speed "info" from the same source, namely the ABS wheel speed sensors. The signal is then "converted" into an mph/kmh figure for display on the climate and speedo by one of the cars ECUs. That is why the raw data can be adapted on the VAG-COM, or at the dealer.
By law, speedos can never under-read, but can over-read by up to 10%, so a genuine 70mph could be displayed on the speedo anywhere between 63-70mph.
My S4 seems to be very accurate, at an indcated 80, using cruise on arrow straight roads, GPS displays 79! :smug:
Sean, example given is the wrong way round - a genuine 70 must be shown on the speedo as 70+ (up to 77). This means when the speedo is showing 70 you are doing less. As you said the speedo cannot under read. e.g. actual 65 speedo 70
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i thought with sat navs, they are not the most accurate due to satellite delay, as in all things to do with satellite due to time taken to send signal from 35000 kilometres away!
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i thought with sat navs, they are not the most accurate due to satellite delay, as in all things to do with satellite due to time taken to send signal from 35000 kilometres away!
Phil, the signal travels at the speed of light and therefore takes about a tenth of a second to go 35k km...Also the delay is constant so you are simply looking at the speed as it was measured a split-second ago... The kind of errors people are seeing with their Mk5 speedo's are far too large to be due to satellite delay.
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Does anyone know if the temp display is likely to be more accurate? Whats the difference between how the speeds are measured?
My educated guess would hedge towards the climate display being more accurate, simply because the speedo is an electro/mechanical component.
They both get their speed "info" from the same source, namely the ABS wheel speed sensors. The signal is then "converted" into an mph/kmh figure for display on the climate and speedo by one of the cars ECUs. That is why the raw data can be adapted on the VAG-COM, or at the dealer.
By law, speedos can never under-read, but can over-read by up to 10%, so a genuine 70mph could be displayed on the speedo anywhere between 63-70mph.
My S4 seems to be very accurate, at an indcated 80, using cruise on arrow straight roads, GPS displays 79! :smug:
Sean, example given is the wrong way round - a genuine 70 must be shown on the speedo as 70+ (up to 77). This means when the speedo is showing 70 you are doing less. As you said the speedo cannot under read. e.g. actual 65 speedo 70
Whoops, senior moment - Doh :rolleyes:. You're exactly right. :smiley:
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i thought with sat navs, they are not the most accurate due to satellite delay, as in all things to do with satellite due to time taken to send signal from 35000 kilometres away!
As illyun rightly stated, that the singal travels at the speed of light - which is approximately 186,000 miles per second (just a touch faster than the v-max on my S4 :grin:).
Don't forget, GPS works mighty fine in Cruise Missiles, which travel anywhere between Mach2 and Mach3 :wink:
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There's also a trick to show your speed on the climate temp display (I suspect people already know this).
I tried this on my way home from work last night - 70 on the speedo equated to 63 on the temp display :angry:
Does anyone know if the temp display is likely to be more accurate? Whats the difference between how the speeds are measured?
How??
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How??
How what? :huh:
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How do you show your speed on the climate temperature screen, and why would you want to do this?
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How do you show your speed on the climate temperature screen,
http://www.golfgtiforum.co.uk/index.php?topic=55376.0 - reply #9
and why would you want to do this?
Dunno . . .
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tested mine tonight against the speed readout from my Tom Tom Go
at an indicated bang on 70mph with cruise on, Tom Tom was reading 67 - tried and repeated on several stretches of road, and it was consistent
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at an indicated bang on 70mph with cruise on, Tom Tom was reading 67 - tried and repeated on several stretches of road, and it was consistent
That's fairly accurate then, did you get the display on the climate up as well?
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nah...couldn't remember how to do that at the time! :embarassed: :grin:
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nah...couldn't remember how to do that at the time! :embarassed: :grin:
OK, you've just found another excuse to play tomorrow :wink:
http://www.golfgtiforum.co.uk/index.php?topic=55376.0 - print off reply #9
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Fellas enough of all this waffle about speedo's :grin:, you shouldn't be speeding you know that :shocked: :smiley: :laugh:, the reason I have entered this thread is this exactly how old do you have to be to HAVE A SENIOR MOMENT ? :undecided: :wink:
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exactly how old do you have to be to HAVE A SENIOR MOMENT ? :undecided: :wink:
Dunno, ask Wayne Rooney !!!! :evil: :evil: :evil: :evil: :evil: :evil:
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nah...couldn't remember how to do that at the time! :embarassed: :grin:
OK, you've just found another excuse to play tomorrow :wink:
http://www.golfgtiforum.co.uk/index.php?topic=55376.0 - print off reply #9
Tried it at the weekend...at 70 mph, both Tom Tom and climatronic display show 67 :)