Inaccurate Speedometer

[rmyin]

anyone notice their speedometer is off? I've been matching it to my GPS and my speedo is definitely off. Maybe it was V70 setting and it was never adjusted to the larger tires of the XC70 at the factory.

Anyone else?

[Jules]

Tire size/width/aspect ratio will make a difference in actual speed. What size tires are you running?

Cheers
Jules

[rmyin]

Tire size/width/aspect ratio will make a difference in actual speed. What size tires are you running?

Cheers
Jules

Stock size... Originals from the factor still. I know this kind of stuff happens when it's common platform. ECU might have been incorrectly programed as a V70 instead of the XC70 tire size.

I just wonder if someone else has experienced this.

[Pennhaven]

Stock size... Originals from the factor still. I know this kind of stuff happens when it's common platform. ECU might have been incorrectly programed as a V70 instead of the XC70 tire size.

I just wonder if someone else has experienced this.

My '04's speedometer matches the GPS quite closely. Your theory makes sense. Maybe someone can tell you if the speedometer can be reprogrammed using VADIS.

[billr99]

There is another thread on this subject on Swedespeed and in that thread it is mentioned that the EU spec allows speedos to be out by as much as 9km/hr. The basic idea is that the OEMs make the speedo to read high so that the customer will not be nailed for speeding as easily. That is, if the speedo is reading the posted 100km/hr, but the car is only actually going 95km/hr everyone is happy.

I have found that my XC is about 7 km/hr high according to my Garmin. My R was about 6 and my wife's old V70 was about 8.

Cheers,

Bill

[dcandmc]

Of all the cars and trucks I've owned over the past 25 years, I've found my XC70 speedo to be the most accurate. It's spot on with my GPS and also when I run a measured mile on the highway. Everything else I've had has indicated too fast to one degree or another. (Runs you out of your warranty quicker!)

[kain]

My '01 XC70 reads about 2mph faster than is reporting on my GPS.

Previous vehicle was a '96 Saturn SL2 and the speedo was spot on.

[slowflyer]

Tried at 60 and 70 mph today v. the MotionX GPS app for iPhone.

At 60, the GPS said 59.3. At 70, the GPS said 69.4

Has anyone tested against the speedo test sections on some highways?

[dcandmc]

Has anyone tested against the speedo test sections on some highways?

See my post #6 above.

[billr99]

So is everyone running stock tire sizes? Obviously, when comparing to a GPS rolling diameter can have a 1-3 mph difference either throwing the speed off or bringing it in close. In my case, my Gislaved snows are a closer match to the Gramin than my Chinese summer tires. Both are 215/65-16s.

Also there is some inaccuracy in a GPS. My Garmin is an older one and the best accuracy I've ever seen with it is within 6m. Not sure how much that affects speed accuracy, but off is off.

Cheers,

Bill

[tolgatt]

mine is approximately %10 off...i have never driven my car with the original 65 size tires,,,i have always driven it with the 60's ( 235/60/16 ).....it explains the +-%10 difference on the factory speedo quite logically....if yours is off with the original 215/65/16 's than there must be a calibration issue..
i must admit its quite annoying to adjust your speed accordingly all the time but as long as you know your actual speed , its fine i guess

[rmyin]

I'm on OE tires. Mine is not off by a certain MPH, it's off by a percentage. This shoes me that the speedo is not programmed correctly.

Actually, this kind of stuff happens all the time of the production line. I wold assume the V70 and XC70 is produced off the same production line. This means the dash module has to be in production order. Things happen and they get out of whack. I've seen this kind of stuff often. I've seen NA jaguars fitted with UK spec lights. It's quite obvious when the light is going

\___ \___

instead of

___/ ___/

Kind of unsafe. Anyways, OBDII does allow adjustments for these types of things. I just have to decide if I want to spend the money for the dealership to do this. It's actually a problem that happened at Volvo but the car is out of warranty now.

[seth1065]

Funny driving to boston last week , speedo read 70 while GPS read 72. It seems my 01 is 2 miles slow according to my GPS, Stock tires bTW:confused:

[colin]

I have tested my speedometer against two different GPS and also the mile markers(Kilometres actually) and it has always been within a KPH.
That is an exception rather than the norm I think.

My motorcycle was 10% out until I replaced the face plate with a corrected one. That has been well documented for those bikes at least. As posted earlier, some manufacturers do that purposefully due to liability issues.

Other vehicles I have owned have generally been out by a lower amount but have not been right on.