Engine/Transmission (1994 - 1998) Automatic Transmission Shift Points

[DonTX]

I know that the automatic used in my model truck has been modified by some to shift better, but I am just plain unhappy with how mine shifts, and would love to hear from others who are happy with theirs.

My problem seems to be only on downshifts. Under load on cruise control, the transmission allows the engine to lug down and I usually have to kick off the cruise when the EGT starts getting in the red. When it does downshift, it is a rather violent downshift which to the best of my knowledge is a double shift our of OD and out of fourth at the same time, violent and roaring engine all at once. Even when not in cruise, it still shifts harshly the same way.

If I try to just shift it out of OD manually at the appropriate time, the same thing occurs, a violent double shift happens. On a Ford powerstroke I had, the shift out of OD was a very gentle effective shift, then the next downshift was gentle as well. .

I think mine has some adjustment incorrect, but don't know what a proper working one does, or how to correct mine. Would someone share what THEIR transmission does under load and going up a hill or if they have had the same problem?

 

[Bob4x4]

Check your T/V cable adjustment. I like them set up on the tight side,about 1/16" clearance. Have some one in the cab hold the go pedal on the floor while you are looking at the trans end. you want just a 1/16" of movement available on the link.



Bob

 

[DonTX]

OK, am I right in my understanding that the transmission lever would have 1/16 travel left with foot on the floor?

Someone suggested the Throttle Position Sensor adjustment may be a culprit as well, whadda you think?

Check your T/V cable adjustment. I like them set up on the tight side,about 1/16" clearance. Have some one in the cab hold the go pedal on the floor while you are looking at the trans end. you want just a 1/16" of movement available on the link.



Bob

 

[JackStone]

You can test the TPS, it is 1 volt with the throttle at idle. I think you can adjust the rod between the TPS mount and the pump to adjust the voltage.

 

[fox]

So, you don't know what is actually done to this trans?

It sounds like someone tried a shift kit and didn't do it right.

Before you put all the time in it and fluid to drop the vb several times, I'm going to suggest you call these guys/

Diesel Transmission Technology - DTT Performance Diesel Transmission and Power Accessories

They can build a VB for YOUR truck.

So can other trans shops. But everyone thinks they know how/when a diesel trans should shift/lock -up/downshift. And not everyone is right/wrong.

Good luck.

 

[San Felipe Bob]

I hate my shift points too.

I hate my shift points.

It "stacks" the shifts.

Shifts 1,2,3,4 all before 45 mph with light throttle.

Also

Un-locks the TC when you let off the throttle all the way at 60 mph then won't lock back up un less I back off to about 1/8 throttle.

I have adjusted my TV cable and the TPS Voltage.

It still sucks.

My ABS light is on too. .

I think I might need one of those stand alone ATS Valve bodies?



SFB

 

[JackStone]

You might try this, it worked great on my 95. I set it at about 2 volts.

95 Eliminating the TPS on Automatics

You need to get the following:
1)A 5K potentiometer, 1 watt rated. It should have three terminals on the back. I used a one turn pot, you can use a 10 turn if you want finer control.

2)6'-8' of 3 conductor 18 gauge shielded wire. The colors are red, black, and white. Don't use solid wire as it will tend to break easier. I couldn't find any of this so I used a red, black, and green 18 gauge automotive wire and made up a harness. The green was substituted for the white.

I mounted the pot in a small project box and secured this to the dash just to the right of the cargo light switch but you can put it any place you can get it to fit.

Run the wires from the TPS up to the dash. Cut the wires off the TPS leaving a few inches on the sensor. I used insulated push together connectors and on the end of the TPS installed the opposite type that were installed on the TPS wires. This allows the TPS to be easily reconnected should the need ever arise.

The Red wire will connect to the violet with white stripe, the white to the orange with dark blue stripe, and black to black. the violet is the 5V going to the TPS, the orange is the voltage that is leaving the TPS and the black is the ground.

Connect the white to the center connector on the pot and the black and red to the end connectors. If the pot works backwards, reverse the red and black leads. The black should be on the #1 connector and the red on the #3 if the leads are numbered on the pot you have. Seal the connections with dielectric grease to prevent corrosion.

After hooking up, set the voltage out of the pot to about 1 volt. On the pot I used, all the way off was at the 7 o'clock position and full on was at the 5 o'clock position. Setting the dial at 9 o'clock gave me one volt.