Torque Converter Fails Twice in 1 Year?

[kam327]

The same symptoms are reappearing that led my dealer to replace my TC a year ago under extended warranty.

Slight RPM surges in overdrive under low load. Occaisional shuddering when upshifting into 5th and a few times it's shuddered slightly during the RPM surge in 6th. Also it seems to hesitate a bit when upshifting into 5th and 6th. And finally, it's really sluggish accelerating from the first couple of stops when cold.

Maybe it's a bad coil pack? I read somewhere it's a bad CP if when you put a little pressure on the brake pedal during the RPM surges it doesn't stop the surges (therefore eliminating a TC / lockup issue)? Plus, you can feel a little surge in your seat during the RPM surges so it seems like the TC is not slipping but transmitting that surge in engine torque to the wheels.

But how would that cause the slight shuddering? Last time I had these symptoms - or at least the RPM surge and shuddering at speed - dealer replaced the TC and the problems went away - only to gradually reappear over the last few months.

Anybody have a sure fire way to tell between a bad TC or CP?

I'm taking it to the dealer on Monday, right before the 12-month warranty on their TC replacement ends. But my extended warranty is long gone and I'm concerned I'm about to get screwed ...

 

[kam327]

Dealer says this time they're getting a code for the mechatronics unit. They're going to remove and clean it. From googling looks like that could be the cause of TC / RPM issues.

 

[boominXplorer]

I have an 06 v6 that I had a bad shuddering issue with in 4th and 5th gear. I even replaced the soloniod pack with little noticeable change. There was a PCM update availible that fixed this issue and an issue with the a/c blowing warm air at times. It drives like a whole different truck now. Not sure if the same issues persist to the v8 model but its worth a try checking for an update.

 

[kam327]

I'll keep that in mind if this doesn't work, thanks.

 

[kam327]

Dealer says the mechatronic unit is bad. Probably a small piece of debris got in it and caused some damage (probably from when they replaced the TC a year ago). Rather than replace the whole thing for over 2 grand as they suggested we decided just to completely flush it and hope for the best. Unfortunately the symptoms still appear to be there for the most part.

My hope is that it runs fine for the forseeable future albiet with these minor quirks. The mechanic thought the worst case it is just makes the torque convertor wear out sooner. Seems to me the shifting quality could also get worse, or fail altogether. We'll see.....