My speedometer has always been 3mph faster than actual. The odometer is off as well since it is driven by that.

A GPS and the scangauge both show the correct speed. If I go a GPS indicated 65mph, the scangauge will read 65 and speedometer will read 68. This works for any speed. The scangauge odometer will also tick up slower than the one on the dash since the one on the dash is going too fast.

I don't understand how the computer knows the correct speed (since it indicates correctly on the scangauge) but the speedometer and odometer are wrong. Any suggestions?

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FireRanger
2003 Edge 4.0 4wd

How to: Aux light wiring, relays, & fuses
Info: Air intake, air temperature, MAF, and other fact vs fiction
Info: HID Projectors
How To: NO HEAT Troubleshooting Guide

Gnomes

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I've noticed the same thing on mine when comparing GPS speed vs the speedometer but that's weird that the scanguage shows the accurate speed.

It wouldn't surprise me if this was some kind of anti-liability thing. Where they intentionally show a slightly faster speed so they can't be blamed for things like speeding tickets.

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2006 Ford Ranger Sport 4.0 2WD on 32x11.50R15s
-3" Doetsch Spindle Lift


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mines off by 2-3 mph according to GPS.

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Neither would I. But it also throws off the actual mileage of the truck. My truck with 107,000 actually only has about 100,000. Thats 7,000 less miles.

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FireRanger
2003 Edge 4.0 4wd

How to: Aux light wiring, relays, & fuses
Info: Air intake, air temperature, MAF, and other fact vs fiction
Info: HID Projectors
How To: NO HEAT Troubleshooting Guide

mines off by 2 or 3 when i drive by those signs on the side of the road that tell you how fast your going. i always thought it was the tires size but tom might have a point there with the liability.

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Pulled from wikipedia...

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Sold:2004 XLT 4x2 Ext. Cab. 3.0 Mods: 3" spindle, AAL, shackle, 32x11.5 on 15x8s, billet grille, clear corners, flow 40 dumped, line-x, CB/PA, traction bars, lil sound system, auto up down windows
Sold:2005 XLT 4x4 Ext. Cab. 4.0 Mods: ProComp lights w/ HID swap on tabs, 32x11.5 on 15x8s, CB/PA, black out heads/corners, lil sound system, cranked t-bars, flow 40 dumped, line-x, shell, bed rug, 06+ tails, metal tail gate handle since plastic one shattered, OHC, Mustang Dome.

So if you are going 3mph and it is 3mph off that makes it 100% off!

Both of my Rangers are 3mph off.

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my truck is weird because scan gauge and GPS will say i am going 45 mph, speedo will say like 48, then i go past a radar and it says i am going 48, but my GPS which shouldnt be wrong, especially on cruise control, says im going 3 mph slower?!?!?

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08 Ranger Sport 2wd
aFe CAI, 30x9.5.x15 Grabber AT2s, U/D pulleys, flowmaster super 44

"Those who make peaceful revolution impossible will make violent revolution inevitable."
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"Somehow the "god of the athiests" delivers more miracles than all other religion combined than..."

Mine is 5mph off. Mine is probably because of my tires though. I've been thinking of popping off the needle for the speedometer and going down the road at about 50 using my GPS and popping it back on there. Anybody know if that would work?

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Mods: Xcal 2, K&N Drop-In, Line-X, DSG Heads/Corners, 6000k Hi/Low HID's, 6K HID Fogs, Foglight Mod, Throttle Cable Mod, 6.5" Digital Designs, Rockford P400.4, 2 Sundown SA-15's, MB Quart DSC 2000.1d, Cranked T-Bars, 285/75/R16 Nitto Terra Grapplers

I'm going to have to say no. You can recalibrate the speedo for different tires with a programmer though.

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Well the thing is I have stock tires. I shouldn't have to buy a programmer to make it read correctly when it is all stock. Stupid POS.

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FireRanger
2003 Edge 4.0 4wd

How to: Aux light wiring, relays, & fuses
Info: Air intake, air temperature, MAF, and other fact vs fiction
Info: HID Projectors
How To: NO HEAT Troubleshooting Guide

Mine is also off by a couple mph, my car is too, but my tires on the car are about 1/2 inch smaller than stock.

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I have that. And it still puts it a couple mph off. I guess that's as close as it's going to get though.

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Mods: Xcal 2, K&N Drop-In, Line-X, DSG Heads/Corners, 6000k Hi/Low HID's, 6K HID Fogs, Foglight Mod, Throttle Cable Mod, 6.5" Digital Designs, Rockford P400.4, 2 Sundown SA-15's, MB Quart DSC 2000.1d, Cranked T-Bars, 285/75/R16 Nitto Terra Grapplers

THANK GOD! I thought I was the only one that had this problem ahahaaha!

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Old Ranger: http://i6.photobucket.com/albums/y243/8886060/Truck.jpg 306k Miles, and kickin'

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