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Thread: 4x4 4L80E VSS with 128k pulse generator

  1. #1
    Potential Tuner
    Join Date
    Jan 2021
    Posts
    2

    4x4 4L80E VSS with 128k pulse generator

    Hello everyone ive got pretty interesting issue i currently have 1982 chevy k10 with a p59 07 6.0 lQ4 and a 2001 4l80E 4x4 trans. i adapted a np208 t-case to it and currently running the Dakota digital 01-128 pulse generator as my vss. the setup on the truck is completely stock other then k@n filter and 3 inch exhaust, and this sensor spins into the 5/8s inch mechanical cable speed hole on the tail housing of the t case. now the problem im having it is my vss speed on vcm scanner is jumping around badly for example: now in Canada so doing a 110kms it is jumping form 105-124 badly. ive completely tripled checked all my mechanical drive ive even talked to DD and did all there tests and everything is happy. and wiring is all fine as well on ecm green pin21 is vss high so even run separate harness from ecm to vss. ive tried dialing in the ppm and tire revo per mile and all that as best as i can. now believe it or not ive got about 8000kms on this setup with this problem still there. trans shifts ok and such just been babying it, but now when ever it gets a load on it aka towing with tow haul active it then spits out (p0730 -incorrect gearing ratio) and shifts so hard you dam near bust your teeth out. this only happens when towing driving normally it doesn't do the hard shifting or anything. some of the other trans issues are more then likely from the vss not reading correctly im sure i wont drag off into those details more concerned about this vss not reading steady mainly. thanks guys any help would be great!!!

  2. #2
    Tuner in Training
    Join Date
    Aug 2019
    Posts
    19
    1. Do you have an engine controller or just a tranny controller? Your tranny is an 'E' model.
    2. You may be getting interference on the signal wire between the pulse gen and the ECU. You said a separate harness but did you twist the wires at the very least? Try a shielded wire such as a twisted pair Belden cable and isolate the shield at one end and ground it at the other. Run a temporary wire first to see.
    2. I have a 2008 Jeep with a 2016 5.3LT/8 speed auto. When I was in the software for Chev I saw the gear ratio was 3.21 setting whereas I have 4.10. I changed it and it made the shifts hard and it would kick down at the slightest throttle push even at 70mph and would change from 8th down to something like 4th. I changed it back and all good. I recommend you tell the computer you have taller gears like 3.23 or 2.76 etc and try that.