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Speedometer Recalibration

thenose

thenose

New member
Hello all, I have a 2000 GTP I just picked up. The previous owner replaced the stock wheels with 17" ones and, obviously, the speedo is off. Seems to be a fairly consistent 5mph off, if I base it on my GPS's speed. Now, I am more than comfortable with simply subtracting 5mph from my speed when driving, but it is actually my wife's car and she will probably forget, a lot. Is there any effective way to recalibrate the speedo to make it more accurate?

Thanks, I appreciate the help.
 


Thanks guys. By "tune" I assume you mean a tuner?

Can't just move the needle, wouldn't fix the HUD.

Thanks again
 
Yup, moving the needle wouldn't do anything.

I'm sure there are plenty of people in the New England Area that would hook your car up and re-adjust it for you, and hell, maybe even tune it for those MPG's ;)
 


Use this to determine how far off the car is. Tire size calculator

A tuner wont have a "table" but you will be able to correct the 3% it may be off. It wont just affect the speedo it can change shift points tcc lockup ect ect if the tires are that far off.
 
just leave the speedo off and remember how far off it is.

if you ever get a chance to put stock wheels back on, or the right diameter tires, you wouldnt want to have to readjust again. you're wasting time doing it the first time.
 
You have you have to change the tire size in the bcm as well which can only be done with a tech2.

Also note theoretical diameter is not what the pcm/bcm use for tire calcs either.
 


gmpowered said:
Use this to determine how far off the car is. Tire size calculator

A tuner wont have a "table" but you will be able to correct the 3% it may be off. It wont just affect the speedo it can change shift points tcc lockup ect ect if the tires are that far off.
Click to expand...

Other than the wife forgetting about the speed difference, I was also worried about this. I mean, if the computer bases things off the speed and the speed is wrong....

Now I just need to find someone to help with tuning. Having never done this before, what is the typical procedure? Is this a bring it to a shop sort of thing or find someone who likes beer and knows what they are doing?

Thanks
 
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