Sorry about the problem with the original posted file. Strange thing is, until I updated Pico Automotive s/w to latest version, I had no issues inthis respect, but have found now that anything that has a zoomed component (and the options set to "Save just zoomed ....") is also corrupt when I try to open it off my storage device, so that's a bit of nuisance....
I have reattached the unzoomed file here, and hope it doesn't chew too much bandwidth. That's why I just posted zoomed!
Robski, thanks for the feedback, I'll try to respond as best I can below, and come back tomorrow with the rest;
1) No it's not your computer, the s/w is up the spout again. As it happens, the Pico Diagnostic s/w neatly lost me my first test the previous day (exactly same hook-up, rubbish results), hence I've gone back to a manual analysis, so we are all having s/w issues.....
2) Yes, I'm a bit concerned about the 580A current once the motor is turning.
3) The VD at the ground is poor around this "strange" spiking area (which is the reason I zoomed into it), but you should now be able to see that the VD's around the starter ground and battery +ve cable to the solenoid are not too bad under normal cranking conditions. I could get them better (indeed, they are better than they were, after the work I did on the power distr around the battery and fusebox)
4) What also stands out is that the battery droops to 12.1v or thereabouts under pre-crank ignition loads. That is from a stable (removed surface charge) condition of 12.74v - not good. The car puts its lights into "daylight running" as soon as the key goes to pos_2, but I'm hoping to get a good current clamp reading on that and everything else from the starter itself, to see whether the battery is actually U/S. Hopefully this will give me a clue as to a "simulated load" re-measure on the battery.
5) I'm sourcing a new starter solenoid feed relay as I write this. I want to substitute this bit of the starter circuit and re-measure the "spiking" before the cranking occurs. After that, I think that the motor assembly is going to have to come off the car for a bench-test and re-scope away from the car, to get a better picture. The main concern I have is that I don't want to spend someone's money on a new battery if it isn't going to fix their problem. I have the original motor assembly from this car - swapped out last year for a suspected solenoid sticking problem - which I can rebuild onto the car for another measure. Given that I'm seeing a load of spiking on starter engagement, I need to eliminate that from the original diagnosis on the original motor last Spring.