1993 Chevy TBI Distributor Pick-up Coil Playing with an Oscilloscope

1993 Chevy C1500 V8 5.7l TBI. This is the vehicle's 30+ year old distributor body. While chasing down an ignition problem, I noticed the pick-up coil leads had cracked and aging insulation. The bare copper wire underneath was also starting to suffer the green crusties. Since I was in the throes of a complete ignition system refresh (coil, wires, plugs, cap, rotor, etc.), I figure I might as well drop in a whole new distributor.

So, while the old one is out of the vehicle and in the garage, might as well do some experimenting!

The distributor shaft, the rotor end, was chucked in a VFD (Variable Frequency Drive) powered drill press. The modified drill press allows for on-the-fly infinite speed adjustment. And with the distributor so configured, a cheap pocket oscilloscope was connected to the pick-up coil's output connector. The signal being generated is completely self-contained from the pickup-coil and its rotation around the magnetic stator of the distributor. There is no outside power being applied to raise the signal.

And, even though the coil lead wires are crusty, the signal it produces is factory fresh and perfect!

The oscilloscope is a FNIRSI DSO-510. The unit is less than $40 off the Big River Jungle commerce site and less than $30 off one of the more common Chinese direct sites.

There's no excuse for the home gamer not to have one of these cheap o-scopes at-the-ready for basic electrical and system troubleshooting.