secondary trigger timing

[silverliner]

My V8 has a 60-2 triggerwheel, TDC after the primary trigger is 73 deg.
Secondary trigger (camsync) occurs around 42 deg after primary trigger
or 31 deg before TDC 1st Cylinder on powerstroke.
Will this be enough time to leave the 1st Cylinder on top of the output tables (0)?

Regards

[mattias]

If the cam sync uses a Hall type sensor you can also consider triggering on either edge (falling or rising) to offset the signal by the width of the signal.

Use the triggerlog to reveal what is really happening, do this at cranking speeds.

You can construct your reference tooth table and ignition output table as you wish, there is not a fixed order - this system can adapt using these tables.

Ref tooth suggestion  (top to bottom) :
0  105 90 75 60 45 30 15

Then put whatever cylinder lights up at TDC (0 ignition advance) in the same position in the ignition output table, and the rest in reverse order. The cam sync pulse should arrive earlier to have cyl 1 in this spot.

[silverliner]

I did the triggertest yesterday (cranking-speed), clear signals as told at the beginning.
73deg I knew from my old ECU-Configuration: primary trigger (VR, rising edge).
I changed from Trij?kt to VEMS to get more capabilities. I don’t regret it but without the help in here, it would be nearly impossible to get it going.
The triggerlog showed me camsync trigger (Hall, rising edge) comes about 42deg later.
Everything OK so far. I didn’t start the engine yet, because I was hoping to get the information,
where the secondary trigger has to be while 1st cylinder (powerstroke) could stay on top of my output tables (0).
my Ref tooth table  (top to bottom) :
0  105 90 75 60 45 30 15
I learned the rule: primary and secondary trigger not at the same time -> no conflict in my case,
but the later secondary trigger – I assume too – will lead to the next cylinder in firing order.
I know, it is common in VEMS to change and mix around the output tables until it works , but very hard for newbie like me to get used to.

thanks,
I appreciate your support

[mattias]

Ok, I think we have all the facts that we need.  I can only suggest an approach to finding the ignition output table  then.

Use the reference tooth table as it is, the ECU will sync faster and inj and ign will happen sooner when you start the engine.
Make clear markings on the crank, and cam gear if it's visible, of where cyl 1 is at TDC in the powerstroke. White paint is best.
You must have an assistant or a remote button to control the start solenoid so you can crank the engine and watch where cyl 1 ignition event takes place.

Crank the engine, if cyl 1 ignites too early or too late, shift the entire ignition output table one step to move 90 degrees (8 cylinder engine).
Repeat until you have the right order, rough tune with "TDC after the trigger" if more than 10 degrees off. Do this again with the engine running and ignition locked to get a fine tune.

I can't explain it easier than that.

[silverliner]

I have checked the ignition timing with the strobe light, even with the cam signal appears after crank signal, the 1st cylinder on powerstroke is still on top of the tables!
This can mean: It would be adequate cam trigger occurs before TDC?
I have verified all other cylinders, as I have 360deg marked on the belt pulley. Everything is where it should be.
I had to correct the TDC offset a little from 73deg up to 76deg – lock tools are very useful – and now I am ready to go,
thanks for being patient