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We were just doing some calibration of our data collector and test driving, we noticed that when the speedometer gauge shows 80 mph, ODBII reports 77, speedo @ 79, ODBII reads 76-77, etc. We checked at various speeds the guage showed about 2-3 mph more than ODBII we did not go over 95 mph on public Interstates, so cannot say if the difference increases or not beyond 100 mph.

Also, at 80 mph the tach was right in the middle of 3000 and 3250 rpm (6th gear), but ODBII showed 45 to 55 rpm lower. This was pretty much the case through out the rev range as well.

I thought I share :)
 

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Cool thank you! Is that 45-55rpms even noticable on our stock tach?

Robert~
 

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We were just doing some calibration of our data collector and test driving, we noticed that when the speedometer gauge shows 80 mph, ODBII reports 77, speedo @ 79, ODBII reads 76-77, etc. We checked at various speeds the guage showed about 2-3 mph more than ODBII we did not go over 95 mph on public Interstates, so cannot say if the difference increases or not beyond 100 mph.

Also, at 80 mph the tach was right in the middle of 3000 and 3250 rpm (6th gear), but ODBII showed 45 to 55 rpm lower. This was pretty much the case through out the rev range as well.

I thought I share :)
Thanks for confirming that. A ton of people have noticed that the speedo is optimistic. Kinda sucks, but not worth the hassle of getting fixed IMO.

-st
 

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fwiw, i tested mine with a gps a few months ago. i was getting, around 65 mph, a -3.5 to -3.9 reading...

on my previous wrx, using same gps, it was almost dead on.

but the odometer is dead on for about 100 miles. around 200 it's like -.9
 

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You need a Differential when powering and axle>>

according to a GPS i was using... my accord was low by almost 4mph... reads 80 but was actually 76.5.

my dad drove 80 in the STi and said he felt like the speedometer was off. I told him he was right.

just think of it as extra buffer in case you get radared...
 
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