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Nissan VG30 Optical Trigger Scope Question


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I am configuring my new Link Xtreme G4 on my 1984 Nissan 300ZX with VG33ET.   I have wired the ECU and setup the triggers and am evaluating them using the Trigger Scope function.  I am preparing to start the car.

This engine has an optical sensor in the distributor body (cam driven) which reads crank and cam signals.   I have removed the stock optical wheel and fitted a 12-1 wheel from diyautotune.com (pic here https://www.diyautotune.com/product/54-mm-optical-trigger-wheel-for-nissan-l28et-or-vg30e/).  As you can see it has one cam sync slot.

When cranking, The runtime values show an appropriate crank RPM (~350-400), and both trigger 1 and 2 are green. No trigger 1 errors accumulate.  So that seems good.

However, the cam trigger doesnt look very good to me on the scope.  As you can see from the blue trace below, there is one big trigger event, but lots of little jitters as well.  Is this something I should be worried about?  So far i tried changing the filter level from 1, to 2, to 3, but no difference on the scope.



trigger log cam filter 2.jpg

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Hey thanks for the replies!


I checked disc diameter and they were the same between the OEM 360 nissan disc and the diyautotune disc.  I did notice that the DIYautotunedisc had some slight rub marks on it.  The disc is thicker and its flatness isnt very good, lots of runout.  Seems like it could cause issues.

I replaced the DIYautotune 12-1 disc with the OEM nissan disc and scoped the trigger signals.  They look clean to me. Cam and Crank are reversed on the OEM disc, so if I proceed with this disc i would need to swap my wiring pins such that the 360 (blue) trace is on trigger 1, correct?

any reason not to proceed with the OEM disc? This engine will rev to 7000rpm.  Or Should I try to replace or fix the DIYautotune disc?



trigger log with optical disc.jpg

trigger log with optical disc zoom 2.jpg

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  • 2 weeks later...

One follow up question that may be related. 

The vg30 cas is inside the mechanical distributor housing.  So to set base timing i locked it at 0deg in the software (calibrate under triggers section) and rotate the housing to set timing at the crank pulley.

I ended up needing to type in an ignition offset of -50degrees in order to get the timing close enough to be able to mechanically adjust it. 

-50 deg seemed like a lot to me. Anything to worry about there? Is this typical practice?



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  • 1 year later...

Bringing this one back up.  

My 300ZX z31 was dyno tuned to 450whp and then i took it to the track (road course) for the first time about a month back.   It would run great for a lap or two, then i would experience violent, random misfires at high rpm (light load or high load). The misfires were like a backfire type sound and i could see the tacho jumping.  Once it came off track and cooled down, would rev cleanly again. 

The log doesnt show any trigger 1 sync issues but you can see the rpm looks a bit jittery. For example (attached), with constant TPS i see RPM jump ~500rpms in less than 200ms.   I did not log "trigger 2" or "eccs sync". This is a trigger issue yes?

For now I have ordered a new CAS from pastpowerparts.com.  Mine is the OE one from 1984 - the one they sell is from 1990s nissans which apparently have a better sensor. It can be adapted to my distributor drive.  I also may try to use a 12-1 (DIYautotune) or 24 tooth (AEM) wheel instead of the 360 opto.  Another quick note - the car has aftermarket cams and springs in it. Not sure if harmonics are playing a role. 




trigger issues.png

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