Today my civic would not start, (cranks good). I have a fuel pressure gauge mounted on the fuel filter hose- I checked pressure during cranking and it was normal. I cranked it with my scan tool connected and watched the rpm, it showed about 250rpm on the scan tool during cranking. I had to get a tow home- After I got it home- I pulled #1 wire out of the valve cover and I connected my test light one side to a good ground and stuck the pointed end into the loose wire, I had a friend crank it and I did not observe spark coming out of the wire to the test light. A few minutes later I tried to start it again and it started and ran normally. (so it was intermittent- that sucks). Now I cant replicate the no-start. I measured the coil current with my oscilloscope and a current probe- Coil is drawing about 6 amps and the "ramp" looks good with a gradual rise.

I took the distributor apart and everything looked normal- I put it back together and now I cant repeat the no-start.

I think I was missing spark due to either a bad intermittent igniter or maybe a bad intermittent coil- but I need to have it act up when I have my lab scope ready to know for sure.
I have no CEL and no codes- any ideas?

would i get AN RPM SPEED ON THE SCAN TOOL IF MY CRANK SENSOR WAS BAD? I have not checked the crank sensor at the pcm with my scope yet.

 

Any ideas guys? I have been driving this thing now for 2 days with my laptop and oscilliscope on the passenger seat. I keep a wire hanging out of the passenger window and the current clamp clipped around the black/yellow wire that feeds the distributor power. I went to 3 stores yesterday and it let it run in the parking lot of each store with the doors locked (with laptop running) - the coil has not missed a beat. All measurements look good. I can't repeat this problem.

What this makes me think is that the igniter was not doing it's job, or I may have had an issue with the crank signal getting to the computer.

The thing I need to know is how is SCAN DATA RPM determined? Is this crank signal, cam signal or both?

 

FYI - just a follow up, my distributor cap was allowing the high voltage secondary ignition to bypass the wires. I sprayed water on it while the engine was running and it completely shut off the motor and would not start. When I wiped it off with a dry towel, it started and ran fine. Replaced distributor cap and rotor and now the car is good- water or no.

The day I needed a tow it was very moist out and sprinkling- so I did not notice it for the next week because it was dry. The thing that put me on the right track was a few days later when I went through the car wash she stumbled and died a few times while inside the spray.