So, I have the 98 F150 4.6 parked for 6 weeks whilst I go overseas. When I come back, I noticed the speedometer is reading about 10% high (ie. when I am going 70mph by the speedo, I am actually travelling about 63 mph according to timing the mile markers).
Would disconnecting the battery cause the computer to lose the speedo calibration? The engine runs fine, no MIL. Any other thoughts? Bad VSS? The tires on the vehicle are slightly larger than stock so I would expect the speedo to read a little low.
TIA