Setting up TPS Throttle Position Sensor

[1968 truck]

I purchased a Throttle Position Sensor (TPS) and cable assembly (TCI 377400) to use with the TCI 377500 controller for a 4L80E transmission and a carbureted 396 engine. The install instructions are spars and I noticed an article on transmissioncenter.net/subject.htm (note steps 3, 4, 5,6) which suggests the TPS should be set up so its resistance changes more rapidly at just off idle position than it does as its reaching the full throttle position. They are suggesting the accelerated change brings up main line oil pressure quicker for better transmission life and if not done that way is the reason for early rapid premature transmission failure due to low line pressure at lower throttle settings. I noted they were talking about a 4L60E but that leaves me to reason why would a 4L80E be much different?

I also noted and tested the TCI 377400 if you rotate the TCI TPS on its mount it changes the proportioning of how rapid the resistance changes as the cable is pulled out of the TPS cable assembly.

I will be using my system to pull a travel trailer and would hate to lose a transmission because of low line pressure at light throttle settings.

So my question – should I set up my system to it proportionally give grater resistance change just off idle too and if so what a good setting?

I purchased a Throttle Position Sensor (TPS) and cable assembly (TCI 377400) to use with the TCI 377500 controller for a 4L80E transmission and a carbureted 396 engine. The install instructions are spars and I noticed an article on transmissioncenter.net/subject.htm (note steps 3, 4, 5,6) which suggests the TPS should be set up so its resistance changes more rapidly at just off idle position than it does as its reaching the full throttle position. They are suggesting the accelerated change brings up main line oil pressure quicker for better transmission life and if not done that way is the reason for early rapid premature transmission failure due to low line pressure at lower throttle settings. I noted they were talking about a 4L60E but that leaves me to reason why would a 4L80E be much different?

I also noted and tested the TCI 377400 if you rotate the TCI TPS on its mount it changes the proportioning of how rapid the resistance changes as the cable is pulled out of the TPS cable assembly.

I will be using my system to pull a travel trailer and would hate to lose a transmission because of low line pressure at light throttle settings.

So my question – should I set up my system to it proportionally give grater resistance change just off idle too and if so what a good setting?

The line pressure scaling can be changed inside the program there for leave the rate of the tps allow and there will be no need to worry. The 4l60e by nature is much more sensitive to line pressure changes in 3rd and 4th than the 4l80e. But like i said hook up the tps just like you would a kickdown cable and Bring the line pressure duty cycle to a lower number (which raises line pressure) were need. When doing this a line pressure gauge is necessary. .

[1968 truck]

First question & observation

I made a nice little drawing of a throttle and where the TPS might connect as an example -- showing where the TPS connects. Unfortunately the system won’t allow me to import it. So in your mind visualize a line drawn through the center of the throttle shaft and the TPS connection point on the carburetor throttle linkage. Then draw a line from the TPS access point representing the Angle of connection of the TPS connecting cable. The angle between the two lines would be a right angle (90 degrees). I am assuming that is the preferred access angle of access but noting if a person move the TPS (source of pull) up or down would cause a change in angle – that would change the rate of how fast the resistance would change as the throttle is first set into motion (comes off idle). In my mind anything off 90 degrees causes the point of most rapid resistance change to occur in a different part of the throttle movement range.

Second question

The TPS has a nice little plastic part (with multiple access connection points) allowing the connection to the TPS resistor assembly to be adjusted so it will match the range of motion of the carburetors linkage movement. Now I am able to get close but not exact. If the carburetor exceeds the movement range of the TPS, parts on the TPS are going to break. Now if the TPS movement range exceeds the carburetor’s movement that’s good but you are not allowed to utilize the full resistance range of the TPS. The closest I can get my TPS to match the carburetor is about 1/8 inch from it total range of movement. If I split the 1/8 so I have a 1/16 inch range of safety at both ends of the maximum range of movement --- my starting resistance begins about 150 ohms higher and is 680 ohms less than the TPS resistance range. TPS range is 902 – 7,000 ohms mine is now 1,050 – 6,320 ohms. How will this affect my system and is this acceptable?

First question & observation

I made a nice little drawing of a throttle and where the TPS might connect as an example -- showing where the TPS connects. Unfortunately the system won’t allow me to import it. So in your mind visualize a line drawn through the center of the throttle shaft and the TPS connection point on the carburetor throttle linkage. Then draw a line from the TPS access point representing the Angle of connection of the TPS connecting cable. The angle between the two lines would be a right angle (90 degrees). I am assuming that is the preferred access angle of access but noting if a person move the TPS (source of pull) up or down would cause a change in angle – that would change the rate of how fast the resistance would change as the throttle is first set into motion (comes off idle). In my mind anything off 90 degrees causes the point of most rapid resistance change to occur in a different part of the throttle movement range.

Second question

The TPS has a nice little plastic part (with multiple access connection points) allowing the connection to the TPS resistor assembly to be adjusted so it will match the range of motion of the carburetors linkage movement. Now I am able to get close but not exact. If the carburetor exceeds the movement range of the TPS, parts on the TPS are going to break. Now if the TPS movement range exceeds the carburetor’s movement that’s good but you are not allowed to utilize the full resistance range of the TPS. The closest I can get my TPS to match the carburetor is about 1/8 inch from it total range of movement. If I split the 1/8 so I have a 1/16 inch range of safety at both ends of the maximum range of movement --- my starting resistance begins about 150 ohms higher and is 680 ohms less than the TPS resistance range. TPS range is 902 – 7,000 ohms mine is now 1,050 – 6,320 ohms. How will this affect my system and is this acceptable?

The way our Gen 2 computer works is it is irrelevant of what ohm or voltage you start as long at the signal wire is going from a lower voltage at idle to a high voltage at WOT. If the way you have your TPS set up happens to pull the TPS at a different rate this can be EASILY compensated for in the software.