Dan64456

5 spd manual, V8...

You ever see those damn your speed is " ". things on the highway they put up near work zones? Every time I pass one, it seems like my speedo is 3 - 4 mph fast compared to those... Weird thing is, even when I put the cruize control on, and reset the average speed monitor, the same thing happens... the average speed in the message center reads 3 - 4 mph slower than what is indicated... (is 70 is on the speedo, 66-67 is on the message center...) Did anyone else notice this? Did they do this on purpose?


Also.. are the fog lights aimable on the GT?

Thanks

BLACK06GT4ME

checked mine with a GPS and found the same thing 3 - 4 MPH slower. I have 17's so 18's would probably take that down to 2 - 3. Ford dealerships usually won't make any correction unless it's more like 7 - 9 mph difference. My wife and kids said it is a safety feature to keep me from getting tickets. Doesn't really bother me, I drive with the flow of traffic. Look at it this way ...... all your times at the track just improved.

Dan64456

Or you can also look at it this way... If the odometer goes by the actual speedo, and not the message center readings, then you could be getting premature miles on your baby...

And I did the tire size calculator on the 235 55 17's, compared to the 235 50 18's... It is a 0.2 MPH difference at 60MPH lol... Now that I think of it, my lincoln towncar was the same way.. The actual speedo read 3 - 4 lower than the message center as well... very weird.

Rrruss

I was noticing that I was doing around 5 mph over just to keep up with traffic. I had my buddy pace me at 50 mph on his car and I was showing 55 mph.

Went to the dealer and even though I only had 700 miles on the car they were going to charge me for a speedo calibration, after a talk with the service manager I agreed to pay if I was wrong about it being off.

Well I was right, and after they reprogrammed it for the right size my speedo and traffic are back in sync.

NOTE: The dealer had some aftermarket $3000 tires and rims on it when I originally test drove it (probably why an '05 was sitting on the lot in March of '06). I made them put on the original premium wheels and tires as part of the deal when I bought it.
The dealer claims they do not recalibrate to compensate for the different size when they add aftermarket wheels, so if thats true it must have been delivered from the factory with the wrong calibration. My car was built in May of '05.... maybe they had a run of cars that were all flashed with the wrong size tire and wheels?

W1ldcat

I haven't checked my Stang, but my Explorer was way off and it had the tires the door sticker said it should. I took it in and the service Manager tried to just scare me off by telling me it would take days to change out the whole dash and I would be without a car. I told him to just recalabrate the computer and he said no way. I then asked him to just have one of the guys check it out. That person did and just changed the computer to make it a lot closer. It was off 10%. I noticed on a trip I have driven for years that's 300 miles all the sudden was over 330 miles with the new car. 10% is a bunch. I had to go 66 to go 60 etc... Not to mention the extra miles that the car would show that it didn't have.
Now I'll have to check my Stang. Thanks for reminding me..

Dan64456

Just confirmed that when I am reading 64MPH, a 2002 Grand Am GT is reading 60MPH... same as the 'Your speed is' signs... That is a 6.66666666667 percent difference. Do you think I should take it to the dealer? That is an extra 6,667 miles on my odometer when I hit 100K.

Dan64456

and check this piece of info out...

"Speedometers delivered from the factory can be inaccurate. Some cynics complain that manufacturers purposely calibrate speedometers to read high so that the odometers (whose calibration is related) will read high resulting in a shorter warranty! We don't have any first-hand knowlege of such a practice. "

This is via http://www.web-cars.com/math/speedometer.html

Stoenr

get a tuner and calibrate it yourself maybe, and gain some HP on the way.
What I wonder is if you do this, is it accurate then? or is it something coded in the pcm that adds the extra mph no matter what you set tire revolutions to.