TDC sensor? Got me, but since they are I beleive, talking about re-indexing the distributor, they may mean the cam position sensor (inside the distributor).
The symptom for re-indexing the distributor is bucking or surging of the motor, is that your problem?
I´ve unplugged the cam position sensor on mine, with no noiceable affects at idle. I routinely clean the plug under the distributor for the cam position sensor, as I´ve often found them oil soaked or moist inside/corrosion. Very low voltage, doesn´t take much to interrupt the pulse.
The distributor in my 88 had an amazing amount of play, due to worn drive gears and thrust wear. I could twist the rotor 3/8", without forceing anything and lift it almost as much. Worth a look.
A poorly indexed distributor usually showed up, when the vehicle was fairly new. Play can cause the indexing to change (distributor, timing chain), as will an after market cam. Crossfire, bucking or surging is often, corrosion in the distributor cap and/or faulty plug wires. Sometimes non-resistor plugs will cause crossfire.
The test sets, tell you the values of a specific sensor are out of the acceptable range. Which can be a faulty sensor, wiring, connectors or tolerances.
TDC sensor may be the CPS (crank position sensor). Maybe somebody else has some imput.
If you really think you have to re-index your distributor I can talk you through it, not real difficult. I have a little trick, not in the book that may be helpfull.
