Cas issue

[nash47]

Hello , im new here and i have A31 home build 

RB25det neo stock eng / turbo 

aem ems 2 blue connector 

aem 3.5 map

aem cas disk

aem wideband connected to ecu 

355 lph pump

550 nismo yellow injectors side feed

aftermarket regulator 

and won’t start with base aem tuner basic tune

eventually flipped cas 180 degree so it triggers on correct stroke not in exhaust cycle 

Now it won’t start

Wideband reads 10 and 11 at lowest fuel setting 

and will share calibrations soon for aem tuner i think something is wrong in aem tuner 

 

please if you have any information, am very grateful 

 

 

 

 

[GTSBoy]

6 hours ago, nash47 said:

Now it won’t start

Wideband reads 10 and 11 at lowest fuel setting 

The wideband reading is meaningless if it's not running.

Why are you using shitty old sidefeeds on any engine, let alone a Neo? What manifold and fuel rail are you using to achieve that?

Beyond that, can't help you with AEM stuff as I've never been their ECU/CAS combo.

[TurboTapin]

20 hours ago, nash47 said:

Hello , im new here and i have A31 home build 

RB25det neo stock eng / turbo 

aem ems 2 blue connector 

aem 3.5 map

aem cas disk

aem wideband connected to ecu 

355 lph pump

550 nismo yellow injectors side feed

aftermarket regulator 

and won’t start with base aem tuner basic tune

eventually flipped cas 180 degree so it triggers on correct stroke not in exhaust cycle 

Now it won’t start

Wideband reads 10 and 11 at lowest fuel setting 

and will share calibrations soon for aem tuner i think something is wrong in aem tuner 

 

please if you have any information, am very grateful 

 

 

 

 

Your best and only option is to verify your CAS is reading properly with an oscilloscope (I'm presuming the V2's had a built in one) and then properly sync your ignition and mechanical timing using your offset angle within the ecu. I don't understand why you flipped your CAS. 

Edited August 18 by TurboTapin

[MBS206]

34 minutes ago, TurboTapin said:

Your best and only option is to verify your CAS is reading properly with an oscilloscope (I'm presuming the V2's had a built in one) and then properly sync your ignition and mechanical timing using your offset angle within the ecu. I don't understand why you flipped your CAS. 

I'm going to assume they flipped it, as the timing setup in the AEM is catastrophically wrong.

Once it is fixed, they'll likely need to swap it back to normal.

[nash47]

This is aem disk setting in aem tuner and still 180 dgree off or ignition on exhaust cycle is it from cas it self as cas seems wouldn’t fit in cam shaft if wrong position and wiring been verified any ideas 

[GTSBoy]

5 hours ago, nash47 said:

This is aem disk setting in aem tuner and still 180 dgree off or ignition on exhaust cycle is it from cas it self as cas seems wouldn’t fit in cam shaft if wrong position and wiring been verified any ideas 

Wanna rewrite all of that in, say, 2 or 3 separate sentences, so that we can read it?

[MBS206]

Have you done the Ignition Sync Wizard in the AEM software?

[nash47]

59 minutes ago, MBS206 said:

Have you done the Ignition Sync Wizard in the AEM software?

Did and sync timing with light 

[MBS206]

15 minutes ago, nash47 said:

Did and sync timing with light 

Was that with the cas upside or correct way up?

[nash47]

 

1 hour ago, MBS206 said:

Was that with the cas upside or correct way up?

Upside and almost start but on original position it keeps backfiring 

[MBS206]

Have you checked cam to crank timing and confirmed balancer marks are correct?

[nash47]

7 minutes ago, MBS206 said:

Have you checked cam to crank timing and confirmed balancer marks are correct?

Yes sir am asking is there possible way from aem tuner from wiring pins 

[MBS206]

4 minutes ago, nash47 said:

Yes sir am asking is there possible way from aem tuner from wiring pins 

It will be a software setting.

I don't believe many on here ever used AEM. And they're now a discontinued product,that's really hard to find any easy answers on.

If it were Link or Haltech, someone would be able to just send you a ECU file though.

[nash47]

On 24/8/2025 at 2:04 PM, MBS206 said:

It will be a software setting.

I don't believe many on here ever used AEM. And they're now a discontinued product,that's really hard to find any easy answers on.

If it were Link or Haltech, someone would be able to just send you a ECU file though.

Thats what im trying to solve bro 

no one with aem tuner experience would advice 

much appreciate 

[joshuaho96]

On 24/08/2025 at 3:58 AM, nash47 said:

Yes sir am asking is there possible way from aem tuner from wiring pins 

Could be falling edge/rising edge is set wrong. Are you getting sync errors?

[nash47]

On 8/9/2025 at 7:56 AM, joshuaho96 said:

Could be falling edge/rising edge is set wrong. Are you getting sync errors?

No sync errors , i have installed AEM disk will return original 360 slot disk and check if there’s any one with running AEM disk could share setup 

[joshuaho96]

10 hours ago, nash47 said:

No sync errors , i have installed AEM disk will return original 360 slot disk and check if there’s any one with running AEM disk could share setup 

The OEM disk will not work on any AEM ECU, you need to use the one they made. You shouldn't have to flip the CAS or whatever you were describing, if you set the ignition sync offset correctly it can't backfire. Make sure you're using a spark plug lead on coil 1 instead of the timing loop to avoid weird issues with the timing light. Double check that your timing settings are actually correct, like is the 24 tooth configured correct or should it actually be 12 teeth for 1 crank revolution? I also found this:

305817248-AEM-Undocumented-Settings-v1-2.pdf