OK, heres the story. After reading a thread here, and wondering myself for a while,

Is there a way to change shift points on our transmissions......?

APPARENTLY, 1999-2003 PSD's trannys shift based on a tourque sensor, as opposed to a throttle postion one.

Now, there must be a wire, from the tranny to the pcm, that is carrying that value, which if changed should change the shifts.

Lets say for dicsussion sakes that its a resistive sensor, and 5v is used to probe it. Lets say :

@0 ft/lbs = 0volts
@100 ft/lbs =1.00volts
@500 ft/lbs = 5.00volts

Now, lets say your cruising up a hill, and engine starts working hard. Now the PCS reads say 3 volts and realized its time to shift.

What i'm saying, is a resistor in line eith that wire would drop the return voltage by a %, tricking the PCM into thinking theres less tourque than there really is.


Anyone got any ideas, or insight as to this working or not?

I'd like mine to shift lower too, wondering if this could work.....

 

I think that you might be on to something here. if this is true than you may be able to put in a variable resistor to adjust your shift points.

 

very interesting... see, now I didn't realize that they had made that change from throttle position to torque sensor, that right there may be the big defferance in my '96 pulling so much better in OD than this 2000. I didn't know if it was the trans. or the rear end gearing or what. I like where this idea is going, unfortunately I'm not smart enough to help out much, but I'll keep an eye on this thread!

 

Interesting idea Parkland. I solved that problem by buying a stick shift. I glanced through my manual trying to see if I could help, but didn't have much luck.

Have you looked through the tranny section on a service manual to see if you can figure it out?

2002 Workshop Manual

 

Cute idea, but it has no basis in fact. There is no torque sensor.

For as long as Ford has had electronic transmissions (the first one was the E4OD in 1988) the shifts are based on throttle position and vehicle speed. That has been true from 1988 through 2008 and beyond.

There are several wires between the trans and the PCM. There are wires for the shift solenoids, the pressure solenoid, the torque converter clutch solenoid, the fluid temp sensor, the turbine speed sensor, and the output speed sensor. Torque sensors are WAY to expensive to install in a truck.

The PCM does calculate engine torque. It uses sensors in the engine to make an approximation of engine torque. This is used to set pressures for the shift, but it is not used to schedule shifts.

There are aftermarket chips that can change shift points. There is no wire that you can modify to change shift points.

 

Thanks Mark I was hoping that you would chime in and let us know.

 

Sorry for the false hopes, guys.

I read in FTE's forums somewhere that starting in 2002 they started using some type of tourque sening to determine shift points. Must have been a little mistake.

 

aw heck, that's allright, the wealth of knowledge on this board is awsome, and it seems that most folks are real good about it, not cocky and they don't make others feel stupid for askin' stuff or having ideas, unlike some of the other forums I've visited. Now we know and all learned together, the info. that someone such as Mark (and several others on this forum) can provide is simply priceless for those of us wanting to learn more about our rigs, and maybee save some money doing home repairs, too.