Link G4 plus not always starting.

I built a car a year ago. And it seems it randomly will not fire when trying to start it. Then I turn off ignition, turn it back on and it fires instantly. This is on A GM LS 3. Using factory gm 58x crank trigger and 4 x cam sensor. I have replaced both sensors with no change. I even went as far as installing a MSD 4x pick up on front of crank with no change. It happens so randomly, it is hard to pin point. I thought it was isolated problem with my car that I wired myself, until today. We have brand new build in drift car. Professionally wired by A reliable and proven harness builder. Same similar set up using all brand new gm sensors on a LS3 using G4 plus. It does exactly same thing. IT is really hard to test due to once I turn power off and back on, it fires instantly and runs perfect with no miss fires. It acts like coils are not firing. But I cannot confirm that. It is almost like the coils are not firing. Perhaps the cam is not syncing up. Anyone else seen this problem or Have an Idea where I should start looking? Thank you in advance Ken Buys

Sorry for the slow response, I dont get to check in here very often. For future link specific support you will get faster response if you post on the Link forum.

It sounds more like it is mis-syncing. If it mis-syncs the spark will be 360 out, firing on exhaust stroke and will continue that way until you stop cranking, it will only re-sync on the next crank attempt. Have you tried both of the LS2/LS7 trigger modes? There are 2 different positions for the cam pattern, if you use the wrong trigger mode the sync location can be borderline. Most 58X USA productions engines use the "90 offset" triggermode, if you attach the triggerscope capture I can confirm the correct one for your engine.

The MSD crank trigger wouldnt work unless you also fitted a single tooth cam sync.