Speedo Wrong by 7mph

Salmon · 25th May 2014, 23:46

My seedo recons I'm doing 80 and my sat Nav say's 63 .
I've got the original spec 16" wheels that came with the Connie so how do you recalibrate it?

Dragrad · 25th May 2014, 23:56

Thread moved to appropriate forum. Re-direct left in old.

Dorset Bob · 26th May 2014, 01:19

I make that 17mph.

If it is 7mph that would be 10% out, which many people report as their error.

I would not take the Gps as gospel as they invariably under read. Unless you are in the cruise, at a constant speed, on a level and straight road.

Are you running on 215/55s on the 16 inch wheels?

kaiser · 26th May 2014, 05:40

Maybe the poster should make sure what the situation really is.

Many Rovers over read by about 5 to 7 per cent on speed.

thundercat · 26th May 2014, 05:45

According to my Sat Nav while tootling along at an indicated 70 showing on the speedo of my CDTI I am actually doing 65

HarryM1BYT · 26th May 2014, 08:39

Quote:

Originally Posted by kaiser

Maybe the poster should make sure what the situation really is.

Many Rovers over read by about 5 to 7 per cent on speed.

It is actually a very precise amount of over read on all cars, derived from the O/S ABS sensor, then fed into the IPK. The IPK then adds a precise +% so as to deliberately over read. The only possible small variations are in tyre size (upto 1mph), or much less likely (because an ABS fault would appear) as fault in the ABS sensor.

There is not as yet a known fix for it, other than getting the IPK with matrix display, reprogrammed by a T4 guru to show the correct speed data in the display. The IPK is fed accurate data, only the analogue speedo is tweaked in software to show the +5% - everything else is fed with correct speed data.

Your GPS can be relied upon to be accurate on a reasonably straight and level road, where you have good reception.

MrDoodles · 26th May 2014, 09:18

Until the OP confirms what size tyres the car is running and the actually speed discrepancy, not sure anyone will be able to help him further!

Personally, Ed's speedo over-reads by about 2 mph at 80 mph, which I'm more than happy with!

klarzy · 26th May 2014, 09:29

Is the OKP original,
Is the needle on zero when standing still,
Is tyre size and inflation correct,

Normally I fins most cars versus GPS have a -2 mph differential on flat straight road @ 80 MPH.
Most IPK needles are 4-10% higher than reality
The message centre IPK's with MPH display I have seen are pretty much spot on.

My own IPK displays 72 needle versus 68 Digital versus 70 GPS

SD1too · 26th May 2014, 10:01

Quote:

Originally Posted by HarryM1BYT

There is not as yet a known fix for it ...

Yes there is Harry!

Correcting the speedometer reading in a Rover 75

Simon

HarryM1BYT · 26th May 2014, 10:31

Quote:

Originally Posted by SD1too

Yes there is Harry!

Correcting the speedometer reading in a Rover 75

Simon

As I don't have access to that....

If that method involves adjusting the ABS pulse to the entire IPK, then it will cause the rest of the IPK to under read.

25th May 2014, 23:46	#1
Salmon Loves to post Rover 75 Saloon CDTi Connesuer Join Date: Mar 2014 Location: Winchester Posts: 424 Thanks: 251 Thanked 33 Times in 28 Posts	Speedo Wrong by 7mph My seedo recons I'm doing 80 and my sat Nav say's 63 . I've got the original spec 16" wheels that came with the Connie so how do you recalibrate it?

25th May 2014, 23:56	#2
Dragrad This is my second home *None DROWNED** Join Date: Aug 2007 Location: Cardigan Posts: 33,339 Thanks: 1,257 Thanked 1,664 Times in 1,081 Posts	Thread moved to appropriate forum. Re-direct left in old. __________________ Andrew Ich Dien Problem solving is... lateral thinking SEARCH FIRST ...ASK LATER...

26th May 2014, 01:19	#3
Dorset Bob Senior Citizen Rover 75 2.5 Connoisseur SE,Chrysler 300C,124 Spider, Daytona 955i,Honda XL250 & Royal Enfield 650GT Join Date: Feb 2008 Location: The Kingdom of Wessex Posts: 6,976 Thanks: 2,391 Thanked 2,685 Times in 1,686 Posts	I make that 17mph. If it is 7mph that would be 10% out, which many people report as their error. I would not take the Gps as gospel as they invariably under read. Unless you are in the cruise, at a constant speed, on a level and straight road. Are you running on 215/55s on the 16 inch wheels? __________________ Let the good times roll............

26th May 2014, 09:29	#8
klarzy This is my second home none but not gone Join Date: Mar 2013 Location: March, Cambs Posts: 16,437 Thanks: 894 Thanked 4,247 Times in 3,025 Posts	Is the OKP original, Is the needle on zero when standing still, Is tyre size and inflation correct, Normally I fins most cars versus GPS have a -2 mph differential on flat straight road @ 80 MPH. Most IPK needles are 4-10% higher than reality The message centre IPK's with MPH display I have seen are pretty much spot on. My own IPK displays 72 needle versus 68 Digital versus 70 GPS __________________ [SIGPIC][/SIGPIC]….All praise Bananaswan….

26th May 2014, 05:40	#4
kaiser This is my second home 75 Tourer 2.5 Auto, 1.8T, 75V8ZT Join Date: Jun 2007 Location: Johannesburg ZA Posts: 6,200 Thanks: 1 Thanked 859 Times in 613 Posts	Maybe the poster should make sure what the situation really is. Many Rovers over read by about 5 to 7 per cent on speed.

26th May 2014, 05:45	#5
thundercat Posted a thing or two Rover 75 Club SE Join Date: Jul 2012 Location: saxmundham Posts: 1,438 Thanks: 289 Thanked 173 Times in 121 Posts	According to my Sat Nav while tootling along at an indicated 70 showing on the speedo of my CDTI I am actually doing 65

26th May 2014, 09:18	#7
MrDoodles Banned MG ZT+ V6 190 Join Date: Nov 2011 Location: Spalding Posts: 13,245 Thanks: 369 Thanked 1,196 Times in 818 Posts	Until the OP confirms what size tyres the car is running and the actually speed discrepancy, not sure anyone will be able to help him further! Personally, Ed's speedo over-reads by about 2 mph at 80 mph, which I'm more than happy with!