Hello to all!

new member here, first time posting

I have a 91.5 w250 with a 16cm exaust housing, 2full turns on the power screw 8in lift, 37's & stock 3:55. I use to get about 18mpg with an already late shifting tranny 4sp w/od not sure wich one it is exactly. Well ever since i turned the pump up (about 4 months) my right foot has become a lot heavier and now my trans finaly gave, it'll run & shift all the way to 4th but jumps in & out of 4th only and of course doesn't launch as strong.
Point is ever since this im only getting about 12mpg (driving her the same as when i was getting 18mpg) is this entirely due to the trans or is my truck also due for something else like injectors ect. truck has 199k miles

 

anyone? 1st time diesel owner & know close to nothing when it comes to the trans?

 

Well of course the tranny is part of it. The motor has to work harder because the power is being wasted through the converter/tranny.

Sounds like a cool truck, you should post some pics, and also wait more then two hours before asking again, i know were good but we ant super man, lol

 

If you back your smoke screw out and bring your star wheel up a couple turns it will help your mileage. It will also make your truck get outa the hole kinda slow, until the turbo spools, then it should have all the power as before.
I know as much about auto trannies as I do carburetor's, so I've got nothing for ya there.

 

Overdrive is what its jumping in and out of. Its pretty common on these trucks. Try adjusting the TPS (throttle position sensor) it should be in the sticky at the top of the screen. Also the engine needs to see a crank signal. I found the crank sensor wire rubbed through right in from of #1 valve cover were it goes through and little bracket to keep it out of the water pump pulley. I don't think this is your problem but over drive, a/c and the alternator won't work if it has no crank signal. Tps is most likely the problem.

 

well my a/c blows cold and the altenator seems fine so i guess the crank signal is ok, the truck jumps in & out of 4th or OD? right after 75mph and then cannot go any faster. Anything 75 and below and the OD works fine with the button, are these still signs of the tps going bad???

 

Yes, it sounds like a flaky TPS.

 

thanks for all the replies, ill mess with the tps this weekend