Trying to verify crank and cam sensor offsets

[jons911]

I'm trying to get the engine started this weekend, but the ignition sync step is giving me some pause. I'm running an AEM Infinity 506 with Rothsport's 36-1 crank wheel and VR sensor and Clewett's scavenge pump and cam sensor. With a zero trigger offset and ignition locked at zero, the pulley mark is pretty much under the sensor. Based on the number of teeth, that should mean the sensor is offset by about 60 degrees or so. The problem is you can only advance the trigger offset, but the sensor is actually about 60 degrees after the missing tooth (when crank is at TDC).

So I tried setting it at 60 anyway and I came up with the TDC mark for next cylinder. Since they are all 120 degrees out, that means advancing it 300 degrees would bring the #1 TDC to where it is supposed to go. That fits since it looked like I should retard ignition sync by 60 degrees in the first place. I tested that out, and 296.5 degrees advance lined it up perfectly. However, no matter what I changed, the ECU still displayed a sync state of 0 and probability of start of 0.

The installation instructions for the cam sensor are to place the tooth under the sensor when the engine is at 90 degrees before #1 TDC on the compression stroke. In that case, 30 degrees later, the sensor would see the missing tooth, and then another 60 degrees later, the engine would be at TDC.

The system is set to sequential, and the timing light seems to be firing slower than the crank is turning (I've got a piece of tape on the pulley mark and you can see it without the timing light), so it seems that it is actually only sparking once every other cycle like it's supposed to. I'm just a bit uncertain of the huge timing offset and whether it's trying to spark on TDC for the compression stroke or the exhaust stroke. I've read through the following thread several times since it covered the same exact thing, but unfortunately it was left without giving the final settings that worked: AEM Infinity - Trigger offset angle ?

Any suggestions or info is greatly appreciated since all of the people I would call are closed on the weekends.

[jons911]

I rechecked for the sync state and start probability. While cranking, the sync state goes to 1 and the start probability goes to 100%. This was for both the 296.5 degree offset and 656.5 degree offset (296.5 + 360). So the ECU seems happy with the data it's getting, but I still can't see how I can verify that the spark is occurring during the correct phase of the cam.