My wife has a 1996 4.9L E-350 Econoline Club Wagon van. The problem we are having is that the vehicle will not downshift. When you first start it it begins in low and up shifts just fine. When you slow down and then begin to go again the transmission will not downshift to a lower gear. You can manually shift it down by the shifter. The speedometer is working just fine and not bouncing. Curious as to what sensor it would be. The Variable speed sensor on the rear differential or the speed sensor on the transmission. Just not really wanting to replace every sensor if I do not need to. Please help.

 

Are you showing any trouble codes or is the CEL on?

Something like you describe should have a code associated with it---that'd be your most cost effective way to diagnose your issue.

On another note an E350 people hauler with the 4.9 motor?

 

It is on the E350. Only codes so far is the O2 sensors and a code stating it is running to lean. Do not think the O2 sensors should effect the shifting. Only other sensor would be maybe the throttle position sensor .

 

Not familiar with that motor but possibly your PCV valve or part of its connection leading back to the base of the throttle body.

Not sure if that would affect shifting since I believe the ECM controls that.

Can't be much more help than that---------sorry!