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Nissan SR20DET Trigger issues on AEM CAS disc

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I’m looking for help setting up AEM cas on Sr20det running ecumaster ecu

Current settings are:

multitooth, 12 teeth for primary trigger and 1 tooth for secondary trigger, both rising edge ( I tried with falling with same results).

first tooth 0 (the engine won’t start with any other tooth)

angle = 40 to 60 tried almost all the angles between these 2 values.

With timing locked to 15* on ecu and the cas fully rotated clockwise (if I ccw it’s even worse) , I see about -20* with timing light

What can be wrong ? Why is the engine so retarded ? It was running with oem 360 cas, so , mechanically everything is as it should be.

any help would be appreciated!



The timing with one of these trigger discs will be dictated by wherever the secondary trigger input is located. This shouldn't be an issue though and just requires you to change the offset in the ECU to align the timing correctly.

Hi Andre,

unfortunally i dont have an offset configuration option on Ecumaster software, please see the screenshot attached. These are the only settings that start the engine, with timing lock on 15* i see about -20* with the timing light. Tried with all first tooth settings, from 0 to 12, engine only starts at 0.

I just swapped from oem 360 disc (with 4 different slits) to AEM CAS, with engine at TDC on compression stroke, the sync slit is right on the sensor, see 2nd attachment

Attached Files

You ideally want the single "secondary trigger" slot to be positioned directly under the sensor when the crank is at about 60°BTDC #1. Your "first trigger tooth" should remain set to zero and you adjust the "trigger angle" number until the timing measured with a timing light matches what you have set in the "locked angle" setting. The trigger angle should end up around 60-75deg if your secondary trigger is positioned at 60.

Hi Adam, thanks for replying

yes, the secondary trigger (1 tooth) is under the sensor from about 60 BTDC until TDC, the sensor is about 4 outer slots wide so i cant tell exacly whats happening under the sensor. important note: my cas is at oem position (middle), i believe the adjustment is +15 , -15 degrees, i´ll leave it that way for now.

I will try as you suggest

One more thing, i´m assuming that i have the correct ignition (1-3-4-2) and injection (1-4-2-3) firing order, i´m using the recomended settings in the EMU manual for 4cylinder full sequential, is this right ?

It appears that it's the Trigger Angle parameter you'll need to tweak. The firing order for the SR20 is 1-3-4-2.

Hi, i have the same Problem with the Aem Disc and the Emu Black. The Engine wont Start, have you an idee for the right configuration?


My engine starts but its way too retarded, i have to lock timing with 60 degrees BTDC to get the engine idle and measure about 15* with timing light.

I configured First tooth to 0 and angle from 40 to 75 (in 10* steps) but i had no luck, its always too retarded and any angle value above those i tried the engine wont start at all.

Since EMU doesent have a offset configuration like Haltech and some other ECU´s, i cant get the AEM CAS disc to work properly so i had to give up and went back to stock CAS...

If someone knows how to solve this please share :)

Old thread revival.

Bought an AEM 24-1 trigger disc to put in an SR and also ran into trouble getting it to work. But got it running and here to share my info. (shout out to Chris at ECUmaster for the final kick)

AEM 30-8760

Things to note;

There is no 'backwards' to this disc. Seen chatter about that in another thread, maybe for KA's but for SR20 the disc is symmetrical and the holes near the center don't matter which way they go.

We found that rising edge for the secondary trigger put it closer to the middle of 2 teeth on the 24 tooth part, this is desirable.

CAS on this car was not exactly dead center, but you can lock the timing to 10 and move either the CAS or the Trigger angle value until its dead on (engine off though when changing this setting).

Ignition output offset is 2. This is using the stock SR firing order, but for reasons I don't want to try and explain the sequence starts later and offsetting the ignition events solves this. Still wrapping my head around this concept; possibly one could mess with changing the first trigger tooth and making the offset 0 but this is what worked. I think if we made the offset 0 the first trigger tooth would have to be beyond tooth 12, which the software wont allow.

If that paragraph was confusing ignore it except for the first sentence.

The catch here is the trigger wheel is on the cam not the crank, but the ECU things its seeing primary trigger from the Crank. Ecumaster has a few settings for this scenario but they are either the 360 wheel or require a missing tooth or 2 missing teeth on the trigger wheel. Using the "Multitooth" setting means its expecting a trigger wheel on the crank for the primary trigger and the 1 tooth from the cam on the secondary. This is why the tooth count setting is 12 and not 24. Cam spins at half the speed of the crank, therefore to complete a 720* 4 stroke cycle the ECU will see 24 teeth on the primary trigger and one tooth on the cam.

Hope this makes sense to anyone else reading it, and it not just copy and paste the settings and grab a timing light lol.

Attached Files

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