I know the Ford factory speedo's are off by around 2mph by 50mph or so right? That means, when you're speedo reads 50mph, you're actually really going around 48mph?

I've verified this because my Escort 9500 GPS speed shows 48-49-ish.

Couple that with slightly larger diameter tires (305-35-20) in the rear, I am seeing up to 4mph off at much higher speeds of 70-80mph.

It's good for avoiding speeding tickets, but bad just because it's annoying.

So my question is:

How can I fix that, and sync it all together so that the speedo speed is the actual speed, or even within 1mph?

JDM Engineering did my tune and I uploaded via SCT SF3/X3. Can I change it myself on the SCT? if so, how? Or do I need to ask JDM for them to fix it on their custom tune to me?

thanks for the input.

 

You can pop the cluster open and adjust the needles themselves, or try adjusting the tire size in the tune.

 

Do you have any idea if they disabled adjustable parameters? I would get with them and establish this first. You should be able to have it adjusted on the fly if they're enabled.

Alex

 

You can probably adjust it yourself. If your parameters are unlocked and just adjust the tire height a little bit so you can match your actual speed.

 

Or just keep it the way it is, that way you can keep that mileage low....since you never drive your car anyway

 

I keep it a little high to help me avoid tickets.