Here is my .csv file from my datalog this morning. If you look at line 5638 you can see the first MPH jump from 53 to 61 then scroll down to line 5656 you can see it really jumps around to line 5661 Now it looks to me that in one sec and less then 100 RPM change 10 MPH jumps in one sec.

I unhooked the cable from my t56 and spun the speedometer cable with my fingers and everything is spinning nice with no catching or anything. Is my VSS on the back of the speedo going bad or is this normal to see this much swing in the datalog? The Speedometer works great and is not jumping around but to the computer it looks like might be.

 

Well thought I would do a test. I took my cordless drill out and hooked it up to the end of the cable that would go into the T56 and gave it a spin to test it out against the Dash board of tuner pro. First off I can here a tick every 10 to 12 sec in the back of the speedo and sounds to be a binding or something, looks like I got to pull the speedo apart and find that sound.

Full trigger of my cordless drill gets me 72 mph but its still jumping around on the dash board of tuner pro at about 70mph to 75mph.

 

Well I found what was making it jump around.

https://www.thirdgen.org/forums/faq-...-fix-pics.html

Followed the steps in the link. It how runs nice and quiet and like its supposed too. The next test will be to see it if the data log smooths out now.