Interesting Ignition Problem

[brodster]

As some of you know I have a Z20e swapped into my 510. 110000 miles on it. I haven't had a lot of time to tune it really well until recently. Anyways, I noticed some stumbles and miss fires when it is cold and at idle. In fact the last couple of times we started it up after it has been sitting, it runs like crap for a few seconds.

 

Tonight I hooked up an oscilloscope to watch the waveforms on the negative terminal of the coil (some project I am working on). I am not sure if it was my crappy o-scope but the voltage seemed pretty low when the coil fired: ~80V. That may not be accurate but if it is seems low. I think new ignition systems hit 150V+ on the primary.

 

Here is another oddity I haven't noticed before, when I clamp on the timing light sensor to any of the wires the engine literally bogs down. It seems like the timing light is robbing significant energy from the ignition. 

 

Current status: New wires, plugs, rotor and cap. I swapped the coil for another with no change. The dizzy does have some horizontal wear on the shaft, so tomorrow I am going to replace it with a rebuilt dizzy. Could be the ignition module too. Will also probably jumper the main power connections to the ignition to see if there is a bad connection.

 

I am assuming there is some loose connection or worn component, but I am just wondering if anyone has ever experienced a timing light rob enough energy from the ignition system to actually bog it down. Seems odd.