Hi

 

Is it possible to adjust the speedo accuracy using OBDeleven? Mine does read 10% out - ie it displays 76/77mph when doing 70 on various GPS devices. Despite the fact I have tested this on in-car speedcamera GPS detectors (Snooper and 2 different Drivesmart models) and various phones and apps and have confirmed it, I still brake when doing 75 and I see a van on a bridge! I'd much rather have my speedo reading accurately, maybe 1-2mph out at 70, not 6-7 out.

 

Is it possible to adjust it with OBDeleven? I guess it must be possible as the police have them calibrated and then checked each year. But can I do it myself? I suppose I would have to check it with new tyres and worn tyres as the few mm extra tread might make a difference.

 

Or....

 

Since I have a satnav, is it possible to display the actual GPS speed either on the head unit or the maxidot display?

 

TIA

 

Nick 

Edited 10 March, 20215 yr by NikTheGeek

Typically, if the adjustment is anywhere, it'll be somewhere in the instrument cluster coding/adaptions so I'd start there.

 

I'm not aware of being able to display GPS speed at all.

 

I tend to have Waze via Android Auto showing my GPS speed although in my Octavia it almost perfectly matches the speedometer.

I've seen videos on youtube of it being able to be performed on older VAG group cars using VCDS, but they were all PD type engines.

 

Don't know if it's able to be done on CR engines.

There are adjustments for the wheel size that can be made which will change the speedo. @NikTheGeek
Have you change wheel or tyre sizes?

@SashaGrace should be able to point you in the right direction.  Pretty sure she did the same.  Or maybe it was the mpg she did... Sasha?

Without wanting to seen to be a creep, if Sasha doesn't know then it would have to be a dealer thing.

 

TBQH I find it quite odd that you can't put into the infotainment system the size of your tyres, so that you get a correct calibration on your mileage and speed readings. 

I am sure that I have seen speedometer/odometer correction under adaptation in VCDS on my CR engined car, perhaps if I clicked on it it may come up as function unavailable.

57 minutes ago, TheWanderer said:

Without wanting to seen to be a creep, if Sasha doesn't know then it would have to be a dealer thing.

 

TBQH I find it quite odd that you can't put into the infotainment system the size of your tyres, so that you get a correct calibration on your mileage and speed readings. 

Given that it seems to be a struggle for a large number of motorists to even inflate tyres correctly, having the ability to change the tyre spec in the infotainment seems a big ask. 

If you can't do this basic maintenance then you really shouldn't be behind the wheel of a car, let alone own one. 

7 hours ago, varaderoguy said:

There are adjustments for the wheel size that can be made which will change the speedo. @NikTheGeek
Have you change wheel or tyre sizes?

 

It has 17's on it rather than the 16's normally supplied, but it was factory specced with them.

 

Anyway, the wheel size shouldn't make any (much) difference as although the alloys have a bigger diameter, the tyres will have a smaller wall size to compensate.

5 hours ago, MarkyG82 said:

@SashaGrace should be able to point you in the right direction.  Pretty sure she did the same.  Or maybe it was the mpg she did... Sasha?

 

Now if you could adjust the cars MPG via OBDeleven, that would be great and I'm sure a good selling point for them!!

It's an oversight not having a GPS speed display on the infotainment if you have a satnav. It will know the speed, it just needs a software update to enable it. Displaying it on the Maxidot might be a step too far, but there's no reason it shouldn't be an option on the main screen other than lazy user interface design.

 

Anyway, I've read something about a "K" setting for different wheel sizes which allows the speedo to compensate up or down by changing this K value. But I don't know if it applies to mine or where I find the setting. I'll keep looking...

 

Nick

Of course greater the speed greater the variance on the speedo. My Roomster shows 77 on the speedo when 70 on the gps. So at 30 on speedo you are doing 27 actual. This variance saves you if your speed has crept up unwittingly in urban streets passing the dreaded speed camera.

11 minutes ago, edbostan said:

Of course greater the speed greater the variance on the speedo. My Roomster shows 77 on the speedo when 70 on the gps. So at 30 on speedo you are doing 27 actual. This variance saves you if your speed has crept up unwittingly in urban streets passing the dreaded speed camera.

Interesting, both of my MK3s have had a fixed error of 3mph compared to my GPS speed. Same for my missus Fabia. 

I.e. at speedo 30mph the GPS is showing 27mph.

 

31 minutes ago, NikTheGeek said:

It's an oversight not having a GPS speed display on the infotainment if you have a satnav. It will know the speed, it just needs a software update to enable it. Displaying it on the Maxidot might be a step too far, but there's no reason it shouldn't be an option on the main screen other than lazy user interface design.

 

Anyway, I've read something about a "K" setting for different wheel sizes which allows the speedo to compensate up or down by changing this K value. But I don't know if it applies to mine or where I find the setting. I'll keep looking...

 

Nick

Car manufacturers have no interest in having queues of customers asking for their dials to be recalibrated because of the differences between them and the GPS info. That’s why it’s not displayed.  

I can do an MPG recalc, but I don’t think there is a way via coding only to recalibrate the speedo.

1 hour ago, SC03OTT said:

Car manufacturers have no interest in having queues of customers asking for their dials to be recalibrated because of the differences between them and the GPS info. That’s why it’s not displayed.  

 

Good point well made!!

Personally I just bought pro level GPS speedo software for my phone and bring it online when I'm in SPECS camera areas, areas where I know that the local plod regularly do speed traps.

 

I now know that IIRC when my speedo is showing 73 it's actually doing ~70.2 mph really and that's confirmed using a Garmin Sat Nav too.

16 hours ago, SashaGrace said:

I can do an MPG recalc, but I don’t think there is a way via coding only to recalibrate the speedo.

 

What does that mean @SashaGrace and what does it result in? Is it any different to just zeroing the stats on the head unit?

 

thanks

Nick

She means that you can adjust the instrument cluster mpg readings to be more accurate. 

 

You would do a full to empty fuel tank a few times to work out actual real world fuel consumption. Then there should be an adaption to adjust it by a factor (the difference between the reported readings and the measured). 

 

Hope that helps. 

9 hours ago, paulski said:

She means that you can adjust the instrument cluster mpg readings to be more accurate. 

 

You would do a full to empty fuel tank a few times to work out actual real world fuel consumption. Then there should be an adaption to adjust it by a factor (the difference between the reported readings and the measured). 

 

Hope that helps. 

 

Ah, I might try that, thanks!