UPDATE, 40mph vibration TC? injector?
Ok, I have been chasing this low 1300 to 1400 rpm vibration in 4th gear for a while now. I originally found a bad #8 injector.(changed that) Found unplugged(sort of) uvch on pass side, it did not ohm out corectly.(fixed it)
I replaced the tc, changed tranny fluid, tried a different idm.
I replaced the u joints all 3 of them. Even the carrier bearing. Turns out the advance auto u joints were junk. Had the drive shaft shop balance it. We missed the u joints. I brought it back, found them to be no good. Replaced all 3 then rebalanced the shaft. I bought a new tranny mount.
I now can say its pretty good.
Heres the issue:::::
When it sits overnite I get in it to goto work. About 2 miles into the ride the engine temp gauge goes to the first white line.(being at the lower sort of warmed up level) Here is where the truck starts a bad vibration or shuddering like it did originally before all these new parts and repairs, I manually, with a switch unlock the tc(i tapped into the wire and can unground it) The shaking stops and truck drives fine. Keep in mind the motor is still not warm or hot. I have no issues with cold starts. I do not hear a skip. The injectors buzz and cct fine. (Scruffy on here says its driveline) (I aggree)
I continue to drive maybe another 3miles til the temp is fully hot. I can now allow the tranny to lock and unlock on its own. It does not shake any longer.
I now park at work for like 6 hours and come out and the truck is fine. Its only the first start of the day, after the trans warms enough, so that the pcm will allow the tc to lock.(pcm controls it differently til a certain temp is reached) Once its hot its fine.
What in the trans can cause this?