AEM Infinity - Trigger offset angle ?

[IROC 912]

Hi All,

Looking for some guidance on my trigger offset angle for my setup. The car wont start and here is my set up / what I have done to get to where I am.

Application is Carrera 3.2 motor with low pressure turbo using 930 J Pipe, 57lb injectors, GT3076R turbo and treadstone intercooler, with AEM infinity 6 running semi sequential firmware.

I have the clewitt cam sync sensor but have not installed it yet. Assumed that semi sequential firmware did not require a cam sync sensor.

1. Denso COP, running semi sequential firmware
2. Rothsport crank pulley with 36-1 trigger wheel, along with rothsport vr sensor and holder.

I have used the diagnostic firmware to verify (twice) that the ecu wire for coil 1 indeed is connected to coil 1 and so forth up to ecu coil 6 to coil 6. All coils have an earth wire to chassis ground (3.2 manifold stud), and a +12v. I am definately getting spark.

All injectors are also firing, confirmed with diagnostic firmware.

I assumed that the way the trigger wheel is attached to the crank pulley and location of the vr sensor holder, that my trigger offset would be 63 deg BTDC. Using this setting I got a lot of coughing but no fire. After a few days and a lot of reading on the AEM forums, I thought the trigger angle may be 360 degrees out, so increased the software angle to 423 degrees (63+360) and the damn thing fired and scared the hell out of me.

I put a timing light on it and with the timing locked at 5 degrees (rothsport pulley has a 5 deg mark) and the trigger offset decreased to 400 degrees.

I can't get it to rev for some reason but need to confirm my trigger offset angle is in the ballpark of anyone else that may have used this type of ecu / trigger wheel setup. I think the non rev issue may have to do with the trigger angle.

Thanks for any guidance anyone can provide.

Cheers,

Sandeep Syan

[xbmwguy]

If you are on tdc and the missing tooth is at the tdc mark and you have the clewitt vr sensor holder you would be at 49-50 degrees

[Tippy]

If your timing light shows 5 degrees and your pulley is indicating 5 degrees, your offset should be 0.

It's correct.

Unless I'm missing something here?

[IROC 912]

Thanks xbmwguy.

I thought that the trigger angle should be in that range as well but the engine wont fire with that range of trigger angle.

I'm going to pull the fuel pump / injector relays and crank the engine with a timing light connected, while locking the spark angle in the software.

Hopefully this will tell me how far out I am. Fingers crossed !

[Tippy]

Put the offset at 0.

[Tippy]

You shouldn't have any offset with a good wheel and VR bracket bolted to dizzy bolt.

[IROC 912]

Thanks Tippy for the additional input. I won't be able to get to the garage until this evening, but will post my findings then.

Sandeep

[Speedy Squirrel]

Measuring it yourself might be best. The offset angle is just that, the number of degrees between TDC of number 1 cylinder firing, and the end of the missing tooth notch. It sounds like you will be able to measure it easily with your setup, since the trigger is on the crank snout.

[TurboKraft]

Originally Posted by IROC 912

Rothsport crank pulley with 36-1 trigger wheel, along with rothsport vr sensor and holder.

Have you asked Rothsport what the offset is for their trigger package?
It's what Motec calls "CRIP" (Crank Reference Index Position).
Enter that.

Lock timing at 0 degrees in software.
Check with an adjustable timing light, adjust in software if needed until zero on the timing light lines up with 0 TDC on the pulley.
Then rev the engine, check for timing drift (it can be corrected, too).

Unlock timing, proceed with tuning.

[IROC 912]

Thanks for the additional information Speedy and Chris. Looks like I have a bit of work to do and phone calls to make before I can update this thread.

Appreciate the guidance everyone has provided.

cheers,

Sandeep

[Tippy]

Originally Posted by TurboKraft

Have you asked Rothsport what the offset is for their trigger package?
It's what Motec calls "CRIP" (Crank Reference Index Position).
Enter that.

Lock timing at 0 degrees in software.
Check with an adjustable timing light, adjust in software if needed until zero on the timing light lines up with 0 TDC on the pulley.
Then rev the engine, check for timing drift (it can be corrected, too).

Unlock timing, proceed with tuning.

My cheap GSF was 0. Timing is more critical than AFR's. I'd be surprised if Rothsport didn't get their stuff within a few degrees of actual!

[bleucamaro]

As mentioned above, try measuring yourself.

Using a 60 tooth wheel, each tooth is 6°

The example below shows the clocking used on our 356, where the lead to the missing teeth just happens to line up with the TDC mark on the crank pulley. This is because of where the crank sensor is located (custom machined bracket at fuel pump location).

Your software should allow for an adjustment either in degrees or number of teeth to lead the sensor. In my case its 11 teeth, I've seen between 10 and 13 before.

If at idle, your timing light shows 5°BTDC, and the timing in the ignition map shows 5°BTDC, then I think you have it set correctly.

It sounds like you got it to run at idle, was it smooth? Since you got it to run, but it won't rev, what's happening? When you open the throttle, is it reluctant to rev, does it cough or sputter, does it just die instantly?

[IROC 912]

Thanks for the feedback bleucamaro. It idles but does not rev when the throttle is opened ... even fully.

Talked to Rothsport and Earl provided the attached picture of the proper configuration. Yellow mark is TDC #1, red is 30 Deg advanced.




My pulley matches the correct configuration.... cant seem to rotate the pic



So my vr sensor is mounted on the distributor stud and when the crank pulley is at TDC #1, the vr sensor is directly over tooth # 7 as below.



So my trigger offset should be about 60 to 70 degrees ?? I am running semi sequential so the ecu should fire the coils twice per 720 degree cycle ... once at 60 to 70 degrees and then again at 60 to 70 degrees + 360 degrees correct ? There is no cam sync so assuming the ecu does not know which of these two options is TDC for cylinder #1 ??

That leads me back to the start of this thread ... wont fire at 60 to 70 degrees trigger offset but will fire and idle at 400 trigger degrees offset but will not rev, even at full throttle.

Will hook up the timing light again this evening and make sure all is as said. Will follow all the advice given and report back tomorrow.

Thanks for the continued feedback.

Sandeep

[Tippy]

Set it at 0!!!!!!

[Tippy]

They don't sell you an OFFSET trigger wheel!!!

It's not a guessing game.

A proper wheel and VR sensor is TDC out of the box.

Once it's running, you can verify IF you need to move it so many degrees. Whatever that is.

[IROC 912]

Will Do !

A few more hours before I can get back to the garage.

Originally Posted by Tippy

They don't sell you an OFFSET trigger wheel!!!

It's not a guessing game.

A proper wheel and VR sensor is TDC out of the box.

Once it's running, you can verify IF you need to move it so many degrees. Whatever that is.

[bleucamaro]

And your trigger wheel looks like a 36-1 trigger wheel, so count the teeth from the gap to your sensor. FYI, your TDC mark is aligned with the rising edge of tooth 2.

360° / 36 teeth = 10°/tooth. From the look of your pics, I think you're close.

The cam sensor just tells the engine what stroke you're on, running wasted spark is fine.

Per the manual, have you set the base timing (Lock timing @ 5°, verify while cranking only using timing light)?

Theres a ton of other things it can be, and without playing with it, would be hard to diagnose over the internet.

Are the coils wired correctly? ECU to coil & coil to plug? It's possible to get the banks switched

Are all the other inputs wired and functioning correctly? TPS calibrated?

Are you tuning alpha-N off idle, blending to SD?

What happens when you increase the spark advance in the tuning map while idleing, does RPM increase? Does engine sound happier?

[Tippy]

Trigger offset, to me, is made for a few things:

1. Use it to correct minor machining differences between parts and install variances

2. Custom wheel and VR mounts (DIY level)

3. Timing drift for high RPM harmonics and electronic latency


When you purchase an aftermarket crank trigger, it damn well should be TDC or close to it right out of the box.

You should NOT have to put in degrees like 42 or 400. The company should NOT be offering a product for sell in that case!!!!

[TurboKraft]

Tippy -- I think hear what you're saying, that whatever value a trigger manufacturer gives you, that should be it.
But in general, EFI systems do not accept a critical signal at exactly TDC, be it a missing tooth edge or cam synch.
Similarly, they do not have the missing tooth edge and the cam synch at the same time.
Maybe MS/3/Pro is different, but this is how AEM, Motec, and many OEMs are set up (AEM Infinity is an OEM computer).

Sandeep -- we haven't set these up to semi-sequential, only full sequential. Are you trying to trigger 2x injectors at a time, or 3x (aka batch fire, bank-to-bank).
The advice I gave you about locking timing and checking is what we do for establishing the cam synch position. It's probably the same for a missing tooth semi-sequential, but I'd recommend you search AEM's tech forum to verify, or last resort call them.

[IROC 912]

Thanks for all the feedback everyone.

I am confident with the diagnostics firmware that all coils are connected correctly to the proper plugs .. coil 1 to plug 1, coil 2 to plug 2 etc ... and the injectors are also connected correctly.

I went through the setup sync procedure again .... advance locked at 0 degrees with fuel pump relay pulled.

Set trigger offset at 0 degrees and cranked engine with timing light connected to verify timing.

At offsest of 0 degrees ... cannot see TDC mark while cranking.
At offsest of 20 degrees ... cannot see TDC mark while cranking.
At offsest of 40 degrees ... cannot see TDC mark while cranking.
At offsest of 60 degrees ... cannot see TDC mark while cranking.
At offsest of 80 degrees ... cannot see TDC mark while cranking.

So on and so forth untill I hit 380 offset degrees and I start to see the TDC mark.

At offsest of 400.5 degrees the timing mark lines up with the mark in the fan housing.

Frustrating ....

I connect up the fuel pump relay and the car starts and idles, but wont rev .... same symptoms as before. I just cannot seem to get past this step.

Out of frustration, I set the trigger offset to 0 degrees and then cranked the engine for at least 20 seconds and to my surprise, it caught and idled. Sounded great and revved like it should with throttle input ! Connected the timing light and could not see the timing mark at all ....

I then checked the setup wizard, and my settings for the 36-1 Mag crank sensor had disappeared ? Reloaded the settings, cranked the engine ... no start. Shut the ecu off, turned it back on and the settings for the 36-1 mag crank sensor disappeared again

I am sure now that the ecu is not remembering my trigger wheel settings for some reason. Frustrating.

Semi sequential is supposed to fire the plugs every 360 degrees (sort of wasted spark) and also fire the injectors twice per 720 degree cycle.

Not sure if I can install the Clewitt cam sync sensor with the engine installed in the car ??



Sandeep