How to: Nissan RB 24-1 AEM CAS wheel with ECU Master

In this post I'll explain how I struggled and set up the ignition timing with these 24-1 CAS wheels on an RB engine, tho it should be similar or the same on an SR or CA.

I have an RB25DET with an AEM or an AEM type CAS wheel. I did not put it on, i bought the engine like this.

It was very confusing, and I struggled a lot, but at the end I was able to get an ignition event after 2 crank rotations from key turn.

Things you need: Timing light, (if its adjustable then make sure its at 0.) and someone with a good eye or just mount your phone to record and set it to slowmo like i did. I recommend 480 fps at least to get pinpoint accuracy.

First of all, set both cam-crank as hall-optical type with 820 ohm pullup and with no filter.

Now. The ECUmaster software asks for the following:

Secondary trigger: (This is the 1 inner hole on the wheel. Your cam/home/sync signal.

I'll be quick with this. Just select the pattern as 1 tooth, and the software recommends a falling trigger edge, do that. Ive read somewhere that on the SR wheel, or if you have one where the cam hole is longer, then it could matter if you select the falling or rising option cause there could be 15 degrees of difference. I don't know about that. Maybe it also matters for the Primary but well, I tested both with a slowmo camera and it makes 0 degrees of difference. (At the time I could not get the scope to work but I'll check it next time, maybe i can see some difference since if it's more in the middle of 2 crank singals the better.

Primary trigger:

-Trigger type: Select multitooth. These wheels do not have a missing hole in them, and this is your best option. (I did not experiment with the nissan cas option because that requires other things too and it seemed more difficult.)

Trigger edge: I set this as falling because the software recommends it, and I did not touch it ever, especially since it did not make any difference with the secondary trigger.

Number of teeth: Set this to 12. You have 24 holes but since the sensor is on the cam, and you can't tell the ECU where it is physically like on other ECUs, it expects it on the crank, so simply divide the 24 by 2 since the cam is spinning half the speed of the crank.

First trigger tooth and trigger angle: This is where it got annoying and confusing and stupid. (at least for me.)

There's an illustration in the help tab of the trigger wheel config where it shows based on what to set up your first trigger wheel tooth and angle. I'll attach a picture of it. That illustration was very confusing for me, especially how this trigger wheel is working on this engine. I dont think have a complete understanding of it but i think it doesnt matter which tooth you select as your trigger tooth, you just have to tell the ECU how far is that from the 1st. piston TDC in angles. Plus, obviously, you have some limits, but I do not understand why you would need to do that. Maybe someone else could explain, but why can't you just tell the ECU that the TDC is X many tooth from the cam signal? Then you would not have to calculate angles, etc., while keeping in mind that it's on the cam and not on the crank. Also, I tried the illustrated method and nothing worked; its always way off, but I won't trouble you with my struggle.

The point is that I we can use the single cam hole as a TDC identifier and the trigger angle as your fine tuner, so you can forget about that illustration in the manual and forget how you should dial things in this particular case. (Except the fact that the tooth count starts from the cam signal.)

So.

If you take apart the CAS like I did, you'll notice that when the 1st. piston is at compression stroke TDC, the cam hole has just passed the sensor. I did not take off the actual sensor from the case, but I was trying to pry it a bit and looking under it, plus I did some testing, and it seemed like its kinda there or 1 or half a hole after TDC, but that is what i want to use as my TDC identifier, and that is a problem. (or so I thought)

What we know:

-12 crank holes are 1 full crank rotation (because it's on the cam)

-The ECU starts counting those tooths from the 1 cam hole (which is your "home or sync" or call it whatever you want)

-The cam hole is at compression stroke TDC (where it should fire the coil)

Another thing to keep in mind is how to count the tooths-holes as angles. 1 trigger tooth is exactly 30 degrees. Again, since its on the cam, 12 holes are 1 full crank rotation so 360 divided by 12 is 30. So If you type in 6 as your trigger tooth then that is 6x30, so 180 degrees of crank rotation. The trigger angle is 1:1 so 69 degrees of trigger angle is 69 degrees of crank rotation (dont ask me how, whatever...)

The problem:

The ecu will always starts counting the crank tooths in the exhaust stroke because the cam signal just passed, which is where we would've needed the ignition event. So If you try to put in the 9th-10th. 11th. tooth as your trigger tooth and tell the ecu with the triggle angle that the ignition event is coming in x angles, it will fire at the exhaust stroke.

Additional problems:

-The software doesn't allow infinite adjustments for reasons I won't explain. The trigger angle has to be between 30-120, so you cant tell the ECU to wait 400 degrees to fire, and also you cant tell it to count minus trigger tooths or angles.

-There is a setting to offset the ignition timing 360 degrees but i dont like that because the engine has to turn over at least 4 times until it could start.(2 for cam-crank sync, 2 for the stroke adjustment plus its waiting for the TDC) I'd like my engine to start if I turn my key.

-If you think that you are 180 degrees off, theres an injection setting for it but doesn't matter, you wont be needing that. (not an actual problem.. :D)

I sucessfully set the ignition timing with these numbers: 11th. trigger tooth and 110 trigger angle. (dont copy it! as i said, its still at exhaust stroke.) Honestly i dont know how these numbers are TDC but they are. 11x30=330, so i should be 30 degrees away but it needed 110. I have no clue where it counts the triggle angle from, but that could be because the cam signal is at a different position from what i was thinking? I really doubt it, but it doesn't matter either way. As I said, just think of the trigger angle as a fine-tuning element because it works that way.

Next i was thinking, Since its at exhaust stroke and I cant go negative trigger tooth, I could just try 0 as trigger tooth and fiddle with the trigger angle.

And it worked! No ignition offset so no exhaust stroke bs. no nothing. 2 crank revolutions and it fires. perfect.

Correct data is:

First trigger tooth: 0

Trigger angle: 77

You can copy this now, but I think your trigger angle will need adjustment based on sensor location, plus my CAS was clocked exactly in the middle. I know i couldve just typed the numbers but if your CAS is clocked differently or has a slight off position for some reason, you wont know why yours doesnt work with these numbers.

So it seems that the cam signal is just before compression TDC. Maybe its even a couple tooth before it, but i cant really see it because the sensor is quite big and I can't see under it well enough. and I also don't really want to damage it. My theory is that based on the 77 degrees of trigger angle, the cam hole has to be 2 and a half tooth before compression TDC and it counts the trigger angle from there too?? honestly idk and i dont care either. Tho if this is the case and the CAS is clocked too much, the wrong way it might be impossible to adjust it perfectly without the 360 degree stroke-ignition offset.

Additional info for the trigger angle as a fine tuning element:

The less the angle you type, the earlier it fires, and the more you type the later. It makes sense, but here's an exemple:

Let's say your first trigger tooth is 10 and your trigger angle is 100 (which it shouldn't be) and the timing light says that you are 20 degrees off before TDC, then just type in 120 degrees of trigger angle (so +20 degrees since its 1:1) and you are right on time. Of course, if it fires too late, just subtract the degrees you need, but keep in mind that the available range is still only 30-120. which is 1 to 4 tooth of the trigger angle in RB case. It really is just a fine-tuning element.

Hope this was helpful and you have a complete understanding of how the trigger setup works with ECUmaster.

Btw my engine still doesn't start and I think I have some fueling issues because it smells very rich but I can't see anything on the lambda. Could someone check out my map and logs? Pretty please.

Oops, I forgot the picture of that idiotic illustration. I also attached a 1080p 480 fps recording of my timing.

(Edit: I've set 10 degrees of lock so the light is at 10 degrees, which is the third stripe)