My truck is 91 f150 5.8l 351w with an e40d transmission. i pulled codes and nothing came up. it shifts super hard from 1st to 2nd but shifts completely fine through all other higher gears. i only notice it when driving through a parking lot going about 10-15 mph, the truck shifts hard and seems to shift late? anyone have any ideas about what could cause this problem?

 

I'd guess TPS. Mine went bad about a year ago and made it shift rough, especially from first to second.

 

Define nothing..... Did you get the all clear( 11/11 or your truck is most likely 111/111) or as you stated, "nothing". If it is the latter then you have a problem pulling the codes. Try cleaning the STI and ST0 connector pins.

 

i got the 11/11. what is TPS?

 

Throttle Position Sensor. It mounts on the bottom side of the throttle-body. Does the problem get worse as the truck heats up? A bad TPS can be heat sensitive.

 

Ford Fuel Injection » Throttle Position Sensor (TPS) Click on this link to see how to test the TPS.

 

is your speedo bouncing at all by chance? you might pull the rear abs sensor out of the top of the diff and clean it off good and put back on. when was the last time you serviced your rear diff?

 

@kentuckyredneck yes the problem definitely increases as the truck heats up im gonna go with a bad TPS. what do you have to do to replace it?

 

okay so i got a new TPS and i notice a difference but it still didnt fix the problem that i had. it only does this sometimes but it almost seems like the shifter or pedal gets stuck into gear and then all of the sudden it slams back into the right gear? this only happens when going like 5-15mph? it jerks the truck super hard does anyone know what could be causing this?

 

I'm assuming you checked the fluid level already and it was bright red and full right?

 

Take a look at post #7.......

 

okay thanks guys i will try it. sorry my explanations are not detailed i dont know much at all about trucks and its hard to explain

 

thanks guys i changed the TPS and cleaned the rear ABS sensor and havent had a problem occur again yet!!

 

a hard shift from 1st to 2nd means that it's shifting with full line pressure and not the solenoid. This is what I was told by the Trans shop that used to be known for excellent work. I would check the mpls (SP?) and go from there.

 

not trying to hijack the thread or anything but my gas pedal will sometimes vibrate during a shift and at low rpms until it shifts again could this be tps?