Replaced can tensioner now have trigger errors

240SX KA

Was running good - cam tensioner broke - replaced - crank but no start due to trigger errors piling up.

Was running a 360-4 optical trigger - thought that the missing Trig1 signals and variable trigger event durations were due to vibration/resonance so we replaced with a 24-1 disk.

It seems the 24-1 disk is doing the same thing.

Is the way this trigger scope looks indicative of anything?

Thank you for the help.

I have seen something similar just recently with an SR20 CAS where it would have patches of teeth missing (stock disc). I initially assumed the most likely issue was the CAS and the user had a spare so swapped it but the result was the same. I noticed in his cranking logs the battery voltage reported by the ecu was quite low - it would drop to like 6V at the initial start of cranking and only recover to about 8.5V. After messing around a bit he replaced battery, starter and battery cable and now the CAS signal is fine and car runs. His logs still shows batt voltage drops lower than typical on cranking so im not convinced his issue is fully resolved but it is working. The experience with this one suggests to me these may be quite sensitive to low voltage. Also note these Nissan CAS's not only ground through the ground wire, but also through the metal body so you could potentially get some weird behaviour if there was, for example, a bad ground that caused a large ground offset between ecu and engine.

So, the first thing I would suggest is set up ecu logging to log batt voltage at say 100Hz so you can see if anything odd is going on there. Possibly run a couple of temporary new power/ground wires straight from batt to cas as a test.

Here is the thread for your interest: https://forums.linkecu.com/topic/14986-sr20-plug-and-play-attempt-to-start/

Interesting, I read through the thread where you worked on Jason's issue. I do receive one ECU Fault code during these attempts: An Volt 3 below error Low Value.

What exactly is that trying to tell me?

I will adjust the logging parameters to record battery voltage and rpm. Anything else I should put in there?

We have coil-on-plugs so we star grounded everything off of the head. However, I will watch the star grounding webinar to make sure I understand what I'm doing as well.

What would you suggest is the best way to patch a ground and power to the CAS? In other situations, I have used sewing needles to jump wires into the loom.

(I have attached the scope from the previous 360-4 trigger that was giving me issues)

Here is an excel graph of the voltage drop in blue. Goes as low as 6.5V during cranking.

So after doing a bunch of trigger scopes and examining the log files it seems that the CAS misses triggers whenever the cranking pull-down voltage goes below about 8V. Thank you, Adam.

I put the car on a jump start box and all the trigger errors went away. I base timed it for 15 degrees with the proper offset but I can't get it to fire up.

Maybe I have to keep offsetting it by a degree at a time until it gets something it likes?

You may be firing on the exhaust stroke, try adding or subtracting 360deg from your current offset.

That was it! Thank you so much for your help!