ViPEC i88 - Crank No Start - No RPM issue

Hi guys

I have an issue that has me scratching my head a bit. I have an AE71 Corolla with a SR20DET. Engine is managed by ViPEC i88, runs a 50Ignite V3 24-1 Missing Tooth CAS & R35 coils. Car drove perfectly a fortnight ago, went to move it yesterday, happened to be logging to review some cold start data and have no RPM reading at all while cranking.

Trigger scope showing what appears to be a good signal (to my eyes) with 4.1V falling to 0.17V and missing tooth being visible in the waveform. During all start attempts the Trigger 1 Signal shows YES with minimal trigger errors.

I’ve asked my usual tech expert who is very experienced with the Link/ViPEC platform and he also can’t see any reason for no RPM reading, almost like it’s immobilised.

I can see I’m experiencing some voltage drop while cranking, so I charged my battery overnight to rule the battery voltage itself out. Retested this morning, no change to symptoms. ECU stays connected/logging while cranking so I assume voltage drop isn’t bad enough to cause a no RPM issue.

I’ve attached a couple of logs, trigger scope image and my most recent tune file. Would appreciate any insight, feedback or next steps you might be able to share. Cheers, Brad

The issue is undoubtedly with the CAS signal. Came home tonight, unplugged and re-seated the CAS connector and it fired up first crank. I can't see anything different in the logs but the number of cycles in the trigger scope is about 4 x the frequency. I forgot to snip the Good start sample at 200ms Div but you can see from the 2 comparables the 50ms Div is completing a home cycle in ~200ms as opposed to the No start condition where its 1 cycle in ~1 second. If nothing else writing this out has helped me dig deeper. I see a small difference in the min voltage (0.17V No start 0.33V start) as well. I'm going to depin the old trigger 2 wire from plug & ECU, but if you've got any ideas for root cause I'd love to hear them (Adam@Link_ECU I'm looking in your direction :P) Crazy that the No start waveform matches the ECU expected 24-1 pattern even when faulting, so it doesn't throw a sync error, it's just seeing it too slow to register the engine is cranking I assume

Cheers