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Odometer and speedo out?

PostPosted: Mon May 04, 2015 11:11 pm
by windspeed36
Hi all,

Did a bit of Googling around and couldn't find much about my issue. Both my odometer and speedo are out by quite a lot. On what was according to Google a ~60Km trip, my odometer recorded ~79Km. At 111Km/h (speedo), the GPS reads a speed of 100Km/h. Is this purely a result of the Premium 3.0R running 17" rims in what I would assume is an ECU designed for 18's? If so, how difficult a fix is it? I do have a service due in a few weeks but I'm unsure as to a possible cost for the fix. I'm not terribly worried about the speed but rather the odometer reading overall being way out on what it actually is.

Cheers,

Chris

Re: Odometer and speedo out?

PostPosted: Mon May 04, 2015 11:14 pm
by HardwareBoB
what size tyres are you running?

Re: Odometer and speedo out?

PostPosted: Mon May 04, 2015 11:20 pm
by windspeed36
I can't remember a width or height and it's too cold to head outside but I know they're the stock 17" rims.

Also stumbled across this in tuning:

viewtopic.php?f=56&t=27628

Re: Odometer and speedo out?

PostPosted: Wed May 06, 2015 1:25 am
by Adrian2627
Most modern cars under-read. There are all kinds of theories about why but at the end of the day it's normal and generally seems around 10%. I wouldn't say your GPS is bang on 100% accurate either.

There was a bunch of people in the US who were trying to get a class action together against Subaru saying that because their cars actually had less mileage on them than what the odometer said they were losing money when trying to resell their cars. :roll: Don't know what became of it but I guess people will do anything for a $.

Re: Odometer and speedo out?

PostPosted: Thu May 07, 2015 4:51 pm
by fedaykin
You can get a Jaycar speedo corrector. Or run bigger tyres.

Re: Odometer and speedo out?

PostPosted: Mon May 11, 2015 5:16 pm
by windspeed36
Yeah looking at the tire option. Just the cost of new rims and tires isn't great with rego and insurance due at the same time.

Re: Odometer and speedo out?

PostPosted: Mon May 11, 2015 9:36 pm
by alexeiwoody
windspeed36 wrote:Yeah looking at the tire option. Just the cost of new rims and tires isn't great with rego and insurance due at the same time.


Why do you need new rims...? Size of rim has nothing to do with your issue.

Re: Odometer and speedo out?

PostPosted: Tue May 12, 2015 12:30 pm
by RX25SE
AFAIK the speedo is 9% over reading but the odometer and trip meter are accurate. There is a separate input to the speedo.

There is a thread on here somewhere that goes quite deep into it.