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Crank no-start / Possible Trigger Interference? 4AG 20V


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Hi all,

I am working on getting this 4AG 5V motor started on a link MonsoonX. I went with one of the basemaps provided by Simon and updated some of the aux settings to meet my needs. 

My trigger scope seems fairly noisy. This is with Key-on and no crank:

No description available.

I am concerned this may have to do with how I wired up the distributor. It is wired as follows:

Trig 1 -> NE
Trig 2 -> G2

I only used one ground (Trig 1 GND -> G-) from the two trigger/ground shielded cables. I cut the second ground (Trig 2 GND) wire flush with the shielding. Was this incorrect?

My RPM readout also seems to be intermittent between 0-185ish while cranking. 

Will post crank log and trigger scope log in following post.

Thank you!


4age Trigger Scope Log 1.llgx Crank no-start log 4age.llgx 4age 20v 1-17-23.pclx

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Your trigger 1 voltage is borderline, just barely making 0.2V.  Some of that will be because your battery voltage is quite low and it is cranking slow.  So just charging the battery will probably be all it needs to get it happy, but ideally you would want to improve that trigger voltage so it can still start in the future next time the battery is low.  Trigger 2 looks fine as is.  Reducing the air gap between the sensor and toothed wheel will increase the voltage so see if you can do that, I think I remember the 4A had some adjustment on the pick-ups - if not you can often move them a bit by slotting the mounting holes a little or similar.  You can go right down to about 0.2mm air gap if needed.

With trig 1 voltage improved you should then have consistent RPM in the software when cranking and you should have a spark, so the next step is to get a timing light on it to confirm timing is in the ballpark.  If timing looks close enough but you still have no signs of life then it probably means you are sparking on the exhaust stroke so change the trigger offset by 360deg to correct that..  

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Thanks Adam! Took the dizzy out and was disappointed by the pickups seemingly being non adjustable. Did notice they were corroded though. 

Cleaned them up and tried again with a larger battery. Car started right up. 

I appreciate your support :)

Will set base timing now. 


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