4L80E problems

[Maaac1789]

Hey guys. Need some help. Long story short: I have a 1983 K10 that I 5.3 swapped last year. I initially used the 700r4 behind it, but it didn’t hold up. I swapped in a freshly rebuilt 4L80E, and had my programmer do a segment swap with HP Tuners, but we can get it to shift on its own. He can command it with HPT and it shifts, and it will do a WOT shift at around 40mph, but won’t ahift by itself. I checked continuity between the PCM and the tranny plug, front and rear speed sensors, and the TPS. All good. I’m using the NP 208 t case and a Dakota Digital pass through VSS. We changed a setting and got the mph right in HPT, but still no shift. Any ideas? Thanks

 

[4WDKC]

Hey guys. Need some help. Long story short: I have a 1983 K10 that I 5.3 swapped last year. I initially used the 700r4 behind it, but it didn’t hold up. I swapped in a freshly rebuilt 4L80E, and had my programmer do a segment swap with HP Tuners, but we can get it to shift on its own. He can command it with HPT and it shifts, and it will do a WOT shift at around 40mph, but won’t ahift by itself. I checked continuity between the PCM and the tranny plug, front and rear speed sensors, and the TPS. All good. I’m using the NP 208 t case and a Dakota Digital pass through VSS. We changed a setting and got the mph right in HPT, but still no shift. Any ideas? Thanks

Did you repin the harness for the 4l80?

http://lt1swap.com/4l60e_4l80e_harness.htm


Looking to do a similar swap so what tcase did you use and what adapter to bolt it to trans? How much did it affect your driveshafts and is it lifted?

 

[Maaac1789]

I actually bought a 4L80 harness and cut the wires I needed from it, since I had removed the tranny wires when I first did the swap. I’m using the stick NP 208 t case and using an adapter that came behind a 4L80. Bolt holes line up the same even though the 208 is passenger drop. It didn’t effect my driveshafts because I moved my motor forward 1-1/2”.

 

[4WDKC]

I actually bought a 4L80 harness and cut the wires I needed from it, since I had removed the tranny wires when I first did the swap. I’m using the stick NP 208 t case and using an adapter that came behind a 4L80. Bolt holes line up the same even though the 208 is passenger drop. It didn’t effect my driveshafts because I moved my motor forward 1-1/2”.

did you move the wires at the ecm plug like the site above says?

 

[rpcraft]

ARe you running a VSS from the trans or the transfer case?

 

[Maaac1789]

Yes,I repinned the wires at the ECM.
I’m using the Dakota Digital pass through VSS the speedo cable on the transfer case passes through the VSS. Model number SEN-4160, if I remember right.

 

[Maaac1789]

As you know the 4l80 had 2 Soren sensors. The input is in the tranny, but on a 4x4 trans, the back sensor would run off the stock t case, but mine didn’t have that one so I decided to use the DD unit.

 

[Maaac1789]

*speed

 

[rpcraft]

OK, just checking. A lot of guys miss that and its a troublesome issue.

 

[Maaac1789]

Update: I finally found the solution on HP Tuners forum. Because the Dakota Digital VSS reads off the speedo cable instead of the trans shaft, we had to change a few settings under the speedo tab in the tune, so it could properly calculate the correct speed. Shifts like a champ now. Don’t let anyone tell you a pass through pulse generator won’t work. It will...perfectly.

 

[rpcraft]

I know they will, just what happens is people aren't willing to adjust settings very often to account for a budget piece of hardware. A lot of tuners fall into a habit of doing what they know and not looking beyond for answers. Sounds like you did your homework.