When I saw #6 cylinder pattern dropping out for just a frame or two when I revved the engine, I knew I had a primary triggering problem. Please note that I was using a Sun 450 scope. I feel comfortable believing what I see…. In the old days of the LIVE scopes, I would have seen the pattern blip out and then resync…
So when I saw this while reviewing the buffer….
I immediately clipped onto the primary signal wire and used the Lab Scope option so I could see as large a sample as I wanted. If I had viewed it under the ignition/primary function, I would not get the type of sample I wanted. Here it is, remember that this occurred as I revved the engine:
It turned out the owner was a young kid who had no money… What was he doing here with no money? Turns out he used to work at the dealership and was told I would help him out… Thanks guys… Ah heck, I need another “Brownie Badge”
anyway <g>
Since he couldn’t afford the repairs, I disconnected his
vacuum advance to make the truck driveable. The Pole Piece below is attached to
the vacuum advance. When engine vacuum causes the vacuum advance to tug on the
pole piece (to advance timing) it sometimes causes the pickup coil wiring to
open up. Usually vehicles with this problem will get towed in as they are
almost totally undriveable or the pickup coil opens up completely.
