What happens if my trigger signals 'clash'

[r33lew]

I've seen people on here writing about trigger signals clashing, and moving cam sensors / switching from falling - rising.

but what would it cause if they clashed?

I asked because mine are on top of each other..

TriggerScopeLogydcj.llgx

[Vaughan]

What engine/Trigger setup?

Assuming an RB with a 24 tooth AEM disc you would get around this by setting one trigger to rising and the other to falling so that the trigger 2 edge occurs ~halfway between two trigger 1 edges

[r33lew]

It is an rb, but with a 12-1 prp kit.

Understood, im yet to adjust to fix, but what would it cause if they clash?

[Vaughan]

Given that your trigger 1 is just a multitooth with no missing teeth the ECU relies entirely on that Trigger 2 tooth to find not only which half of the engine cycle it is in but also where the 0deg point is in relation to the Trigger 2 tooth. If your selected trigger 2 edge crossed over a trigger one edge of the type specified in the settings then the ECU would see that there were either too many or not enough teeth since the last sync which can result in the engine cutting out until it resyncs or the engine syncing one trigger 1 tooth (30deg) out which can cause bad running and/or engine damage.

By selecting Trigger 1 edge as rising and trigger 2 edge as falling or vice versa you no longer have the syncing edges happening right on top of each other so there is a lot more room for movement between the two before it causes issues.

Personally if I was going as far as fitting a crank trigger to an RB I would aim for a 36-1 or 60-2 crank disk as having that missing tooth means the ECU can know what angle the crank is based on the crank trigger and only needs to use Trigger 2 to figure out which half of the cycle the engine is. It will also sync faster and give more stable timing than a disk with no missing teeth and a lower tooth count.

[Seran]

On 1/13/2022 at 7:11 AM, Vaughan said:

What engine/Trigger setup?

Assuming an RB with a 24 tooth AEM disc you would get around this by setting one trigger to rising and the other to falling so that the trigger 2 edge occurs ~halfway between two trigger 1 edges

Hey Vaughan!, was reading through the forums because of this whole Trigger Signal Clash topic and i encountered a discrepancy between adam's previous reply to someone with the same trigger setup of the author of this post

Here's the Link to the forum post on adam's reply, 

He suggested on an unmodified 12 tooth trigger to set both Trigger 1 and Trigger 2 to falling, but to my understanding on this Forum post. It's more reliable to set Trigger 1 as rising and Trigger 2 to falling to avoid trigger signal clash correct?

[Vaughan]

It depends on your trigger scope, the clash issue above is that the falling edge on both Trigger 1 and trigger 2 occurs at the same time making it hard to determine which side of the Trig 1 edge that the Trig 2 edge occurs, in this case if it is sometimes detected as one side and other times detected as the other side then it will be seeing an angle that is out by 30deg which will cause no end of issues. The way around this is to choose the appropriate pair of edges such that the Trigger 2 edge is in between the Trigger 1 edges and so is always seen as being in the same spot. If Trigger 1 has one edge that is noticeably sharper than the other then you would want to use that trigger 1 edge so that the trigger is more consistent, Trigger 2 matters less as it is only being used for sync and not for actual angle.