sped up speedometer readings

btaylor · Post by **btaylor** » Fri Jun 12, 2009 4:14 am

Hey guys
My '91 gt's speedometer always reads about 20 mph more than I'm actually doing (not sure about the factory tach)
I'm running stock 15" crosslace rims w/ 205-60r-15 tires on them...
Maybe just a calibration issue?

wicked-irocz · Post by **wicked-irocz** » Fri Jun 12, 2009 1:29 pm

has it always done this or is this a recent problem? Whats the tach read at what mph? Auto or manual?

btaylor · Post by **btaylor** » Fri Jun 12, 2009 10:35 pm

Hi
I'm sorry, it's a '90 GT with the 3.1L motor and an automatic trans...
When it's idling in drive, the tach reads 15 rpm...
At 25 mph, the tach reads around 25 rpm...
At 50 mph, it reads 35 rpm...
At 70 mph, it reads 45 or so rpm...

As I said in my 1st post, I KNOW that the speedometer is reading a good 20 mph more than I'm actually doing, because for one, when the car is barely moving at all it reads roughly 20 mph, and when I'm on the interstate the speedometer reads 90 to 100 mph and I KNOW what 70 mph feels like from experience and also by the no. of cars passing me LIKE I'm doing about 70...

btaylor · Post by **btaylor** » Fri Jun 12, 2009 10:36 pm

Forgot to add...I've only had the car a few months and it has always done this...

GTJimmy · Post by **GTJimmy** » Thu Sep 10, 2009 11:13 pm

I know it might sound stupid, but is it set to mph? When I got my Beretta, I ended up getting it cheaper than it should be since it was set to metric and the guy thought it had 170,000 miles on it when really it only has 100,000. If it has the digital gauges, the button that says 'Eng/Met' should be right beside the steering wheel. Try pushing it if you haven't, and see if your mph reading is more accurate.

Beretta.net