GMC Repair: 92 Park Avenue, shudders @ cruise speeds, buick park avenue, cruise speeds


Question
Hi!
I hope you will be able to diagnose my problem.  I have a 1992 Buick Park Avenue (not Ultra, no supercharger), 3800 engine, F17 tranny.  It has 141k miles on it and I just bought it two weeks ago.  The tranny oil was extremely dirty when I bought it, so i had it changed (not flushed) and a can of conditioner was added (brand/kind unknown).  Before this was done, the transmission started acting up by "shuddering" while trying to shift in/out of OD going down the highway on cruise control.  At least I am assuming it is the transmission.  After I had the oil dropped, my mechanic said the condition of the oil was "the worst he's seen".  Sludge, filings, and a plugged filter.  After this was done, the tranny had a hard time shifting from 2nd to third (had to let off the gas in order to do it, possible dirt got into a valve body?).  This happened for a little less than a week, now it is shifting pretty much normally and smooth, but the shudder is still there.  Initially I thought the shudder was due to the OD shifting, but this occurs while on a straight, flat stretch of highway.  Could this be the torque converter?  Please let me know your thoughts.  I hope I have provided you with enough information.  Thanks in advance for all of your help!

Answer
Hi
I would check have your mechanic check the plugs, wires, and coils and ignition control module as a misfire can cause a shudder feeling. Also have him check the fuel filter, air filter, MAF sensor wire for being clean, and if avalible preform a fuel injector flush. Eliminate the basics that may need attention anyway. After any of this work is done, have him test drive with scan tool installed. See if the Shudder does in fact mirror the TCC (Torque Converter Clucth) applying. If so you may indeed have a Torque Converter problem. You also may have an other internal trans problem. I am not a transmission tech by trade, so I hate to venture a guess on what problem it could be.
I do hope this helps, although I feel as if I am not really helping you.
It really sounds like you may have a trans problem.
I hope it helps.
Good Luck
Paul