Low speed misfire in OD/lockup 3.8 V6
My 1989 Bonneville with 3.8 V6 is the one car in my life I just can't part with. It has developed a strange misfire (?). It will only happen when the transmission is in OD and lock-up, and you carefully lug it down to about 1600 RPM. There are isolated jolts that feel like ignition misfire, except that they are very strong. It is not a string of misfires; it is one isolated "thump". Unless you press on the accelerator, the misfire does not cause any change in transmission state--if you continue to carefully lug at low RPM, it will "thump" again in a few seconds. It can not be made to misfire under any conditions other than this. Hard accleration--no misfire. Engine speeds above about 1800--no misfire. Does not seem weather related.
The misfires are so jolting, that I even suspected some trans problem where lockup went out-in quickly. However, my best clue so far is that when I replaced plug wires, the problem became noticeably worse.
ALSO, I need to replace the harmonic balancer, but I can't get the bolt loose on the crank end. The balancer appears smooth on its face, so I don't think a puller is required, just get the bolt out and the balancer will slide out.