i have a 92 f250 7.3 IDI with a e4od. the transmission doesnt shift right and the tach doesnt work. im assuming these are related. it seems to hold gears, shift hard, and search for gears in the 25-45 mph range. on the open road she does just fine.

the tach reads nothing. i thought it would be a simple sensor problem so i ordered a new one from the steelership ($80). i installed it today and still nothing. it seams like the tach will try to jump a little off the post but cant muster the energy.

did i need to put the engine at tdc for installation or something? do i need a new tach? anybody know whats going on?

 

You assume wisely. It shifts and hunts as such because it is in limp mode, because it dunno where is goin on. Interesting, every non-working tach ive read about is bad sensor. Nothing special about putting it in. You will have to diagnose it further, not sure how personally. Sensor isnt getting enough or any, power or ground im guessing, or you have a bad tach. Check connections for starters. Any other gauges behaving peculiarly?

 

the voltage gauge is a little bouncy and then reads high at 60 mph. should just be the voltage regulator. ill get that sorted today.

and the speedo doesnt like to work under 30mph

i have a couple parts trucks back on the farm but it will take me a while to get out there for an extra guage cluster

 

I had a bad speed sensor on the transfer case that played hob with the tach and tranny on my '91.

 

is your overdrive light flashing on the gear selector? mine did that once on a trip home from ohio. the sensor is on the front of the engine on top of the fuel injection case cover. has a rather large nut. i think the price at ford dealer was 90.ish
same truck had another issue in regards to shifting later on that turned out to be the transmission harness on the passenger side of the rear transmission its a bear to get to and i think there is hose or heat shield that makes it difficult but it can be done just unhook it and clean it with electrical contact cleaner. that resolved that issue for me.

 

the overdrive off light is not on or flashing. i have replaced the sensor on the front of the engine next to the oil fill cap. i have not cleaned the harnes but it does not look dirty from the outside. ill look at it tomorrow.

thanks for the replies