1999 explorer sport shifting to 4th too soon - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

slreno · 07-11-2009, 16:56

i have a exploerer 1999 sport. i am not sure if this has a 4th gear or it is shifting into overdrive? or it is lockout? anyway
i can feel it shift a 4th time and it is doing it way to soon? it will shift a 4th time at 25 miles per hour and it is shuddering trying to run at such a low rpm in that gear.. what could be causing this and is there an adjustment for this?
thanks

**360ci** · 07-13-2009, 19:18

There should be an overdrive lockout button on the dash or on the end of the shifter. That will lock out overdrive and keep the vehicle in the gear that is 1:1, generally 3rd in a 4 speed transmission. Normally a shift into OD won't come until around 35mph, and even then, depending on tire size and axle gearing you'll be lucky to do around 1200-1400rpm at that speed. Ford automatics are generally geared toward fuel economy, but that seems a bit extreme to go into OD at 25mph. I'd guess there might be a problem with the torque converter. I'm not a trans man by any means, but perhaps someone else will chime in.

slreno · 07-14-2009, 05:15

ahhh now that you mention tire size! i just bought this used and the person before me has the wrong size tires on this... they have a 225/75/16 when it calls for a 245 or 255 cant remember exactly but that is a huge difference... would that cause it to shift too soon like thjis?

**360ci** · 07-14-2009, 11:45

Quote:

Originally Posted by slreno

ahhh now that you mention tire size! i just bought this used and the person before me has the wrong size tires on this... they have a 225/75/16 when it calls for a 245 or 255 cant remember exactly but that is a huge difference... would that cause it to shift too soon like thjis?

It can, only if the PCM wasn't programmed for the shorter tire size. Width doesn't have much to do with overall height, as it's the diameter that affects the speedo to actual road speed. You can use this tire calculator to check the difference, you'll need rim size, sidewall aspect ratio and tire width Tire size calculator