Transmission input damper

Damage to any part of the damper disc leads to its further destruction. Therefore, it is unlikely that your damper problem could suddenly stop reminding you of itself.

See this topic.
Is this transaxle dead? | PriusChat

You may have other engine and transmission problems that need to be diagnosed carefully. Problems do not always come out in the form of codes. Pending codes can sleep for a long time while the engine is already in a stage requiring intervention.

 

I don't know I'd probably start first with making me sure the engine is in good shape the compression between cylinders is pretty damn close and all of that sort of stuff before I start wanting to pull the engine forward or the transmission back for sure generally a mechanic stethoscope is a good thing to be playing around with during this 20K of hoopla. Anytime you can get the stethoscope out and spend time listening and sometimes you can get right there where you need to be by listening even a long metal bar stuck on the transmission or the engine with your ear near the end of it can work stethoscope would be better but hey. I mean pulling the engine out of a generation 2 was a breeze I mean it's stupid ridiculous easy people with physical impairments can even do it that's almost like changing an engine in an Old 74 Corolla or taking it out I'd want to try and get that as sussed out as possible before I start undoing lots of engine to transmission bolts. But if the rattling comes and goes like you can drive the car a good portion of the day with nothing going on and then all of a sudden pull up to a stoplight and it starts rattling as it's idling down to shut off sounds like the engine's going to almost jump out the car? Then the torque plate would not be a suspect at this point in my mind something else is going on that's causing an imbalance that may be causing the torque plate springs to slam just while that's happening then it goes away for the day or while you're driving or whatever is going on I had a generation 3 doing this I got tired of fooling with it and just left it when the guy who has it now fixes it who I know very well if he figures out what's wrong and doesn't just change the engine I'll post it up and let everybody know as far as I know he's taking the engine and transmission out and taking the thing apart he has plenty of time.

 

Rough starts you say...

My impression is that most of the time when one hears the input damper acting up on a 2nd (or 3rd) generation Prius at startup it is because something on the engine side of it is not right, the engine isn't smooth enough, and the input damper cannot quietly absorb the difference. Best not to let that fester because (also my impression) all that abuse can eventually damage the damper, and that will be a pain to fix.