Speedometer Calibration

[geekme]

My SHO seems to be over reporting its speed. Using several roadside radar displays, my car is reporting 34 mph while all of the radar displays are showing 30 mph. At 25 mph the radar display is showing 23mph. Is this within the margin of error or is this something I need to have the dealer address. I recall Honda having a similar issue where a class action lawsuit was filed. Can anyone check to verify if their SHO is reporting similar speed discrepancies. This would also affect the odometer causing the vehicle to reach the end of the warranty sooner.

 

[Retnavy]

As per my favorite Ford Tech, they are allowed + - 3%. I have an older radar detector which has a GPS in it for speed. At an indicated 70 MPH, the GPS shows 68. I had some work done on the SHO recently, and they reprogrammed the control module. They used the wrong program, and I went on a trip without the detector. Noboby was even close to keeping up with me at and indicated 70. I was actually running 80+. They used the performance program which has a different gear ratio. Sure glad police were napping!

 

[SHOrod]

I have the sport package and have used my GPS to compare with the speedometer since on my Mountaineer the speedo is consistently 2 mph below GPS speed. On my SHO, the speedo is dead on according to GPS.

-Rod

 

[geekme]

I will try and verify my speedo with a gps, it seems as if the difference increases the faster I go.

 

[chrism3784]

A simple way is change tire size. My digital dashes on all my cars are within 1-2 mph with all stock tire sizes

 

[EcoBrick Bob]

GPS will be your true test.

Even with my Factory Nav.... I place my Garmin in Left lower Dash corner and use it as a
digital speedometer.

Brick and 2 G8's were spot on with stock tires. However, my 04 GTO reads fast, but is off the most around 50 mph, and actually gets closer to actual at 75+.

Your Ford dealer has the ability to adjust the ODO/SPEEDO with their programmer, if you ***** enough...

 

[geekme]

I compared the speed with a how and the speed at an indicated 50 mph was 1-2 mph over those speed which fluctuated between 48 and 49. So as "Eco" suggested the faster I went the more accurate it became, go figure.

 

[EcoBrick Bob]

Ford thinks we are more likely to speed at slower mph.....:swing:

Not ME!

Damn near got a ticket yesterday eve just after dark. Was coming home to Clear Lake from a G8 meet and entering I-35 for a 2-3 mi stretch. Came on at about 72 (speed limit 70) and must have confused a trucker that I planned to pass after getting on. He moves to the left lane blocking me, so I squirt by in slow lane and kick her up to high 70s just as I meet an Iowa HWY Patrol car.
See his brake lights and appeared he was coming around.... so I took early exit... and drove slowly home the long way thru town! :sun: Not sure if he actually turned around, but was a WAKE UP CALL!

:thankyou: