next Stage - trigger wheel setup - for waisted Spark

[Agriv8]

thanks Rob,

Hatched a plan on the train this morning.

the 4 12v LED's ( got them flashing in order last night connected to pins 33 through 36 ) so all I need to do is to tie that up with the engine.

The plan is place the 4 led's in the flashing order  around the existing distributor without the cap on  ( still timed in OK ) the plan as the rotor arm points at it we got to make it flash !!!

Regards

Agriv8

[Agriv8]

Howdy,

Bob gone back to basics as sugested and I think I have been a right royal numpty and got the trigger miles out.

a picture of my setup



Reading through the documentation I have set this up all wrong

I have this bolted though the 3 crank pully bolts so can adjust the trigger in 120 deg incremets. My brain has gone soft agin can anyone pont mt in the right direction

thanks

Agriv8

[rob@vems.co.uk]

So the missing tooth passes the sensor 90deg ATDC?
That means that the missing tooth passes the sensor 90deg BBDC.

So unless you're on an odd-fire engine this will mean that the trigger will be 90deg BTDC of one of the other cylinders.

What you need to do is work out which cylinder is on its compression stroke when the slot is level with the sensor, and use that cylinder as the first in the sequence.  Just because your engine has (for example) a firing order 1, 3, 4, 2 it doesnt mean that you have to setup your VEMS in that way, you may be 180deg out so you'd have the sequence 3, 4, 2, 1

[Agriv8]

So the missing tooth passes the sensor 90deg ATDC?

That means that the missing tooth passes the sensor 90deg BBDC.

So unless you're on an odd-fire engine this will mean that the trigger will be 90deg BTDC of one of the other cylinders.

What you need to do is work out which cylinder is on its compression stroke when the slot is level with the sensor, and use that cylinder as the first in the sequence.  Just because your engine has (for example) a firing order 1, 3, 4, 2 it doesnt mean that you have to setup your VEMS in that way, you may be 180deg out so you'd have the sequence 3, 4, 2, 1

So the missing tooth passes the sensor 90deg ATDC?

 >>>>> the missing tooth will pass the sensor about 50 deg ATDC

That means that the missing tooth passes the sensor 90deg BBDC.

 >>>>> BBDC Whats that  ?

but I need to set my 'TDC after trigger (deg)' my TDC after trigger is 310 deg it wont let me set it above 170

For referance my Priamary trigger setting are displayed on the other page.

Thanks

Agriv8

[dnb]

BBDC = before bottom dead centre.

Don't worry that you can't set 'TDC after trigger' to be correct for cylinder 1 - use a different cylinder as your TDC reference and VEMS won't care provided you change your fuelling appropriately.  (With batch fire it probably doesn't matter anyway)

[Agriv8]

Ok so I can use which ever out of the 8 is coming up to TDC on compresion stroke when the missing tooth is lined up with the Sensor.

This is going to get me close but how do I tell the VEMS to wait that last few degress until the piston is at TDC and therfore fire the coresponding coil pack conected spark plug.

Regards

Agriv8

[dnb]

Don't forget that the missing tooth doesn't have to be the trigger tooth! 

The missing tooth is numbered 0.  The first tooth is 1, second is 2 etc...  So set the "trigger tooth" to be say 6 (leave "next trigger tooth" set to 9 (IIRC) as this is an offset from the first trigger tooth) to move around the trigger point.  You then need to set up the 'TDC after trigger' to suit tooth number 6.  Therefore it really doesn't matter where the missing tooth is - VEMS doesn't really care as it only uses it as a reference point.

[Agriv8]

Ahhh light bulb may be flickering on.

So the missing tooth is the referance for the vems.
that tells the vems to start counting teeth when it gets to the tooth I have nominated the Tiger we get a spark.
from that point on we get a spark every 90 deg that the crank - equating to 8 sparks over the 720 degrees.
all I need to do is to tell the vems which coil pack I need to fire at each 90 degrees ( in other words the order ).
As its wasted spark we can set the sequence of the 4 coils to repeat every 360 degrees.

Clear as mud that ( i hope ) .

Will try and draw that up as a picture I work better in picturs and may assist in other installers like me who somtimes stuggle to digest the instructions correctly. 

regards

Agriv8

[dnb]

That sounds like the way I understand it working.  At the very least we're now both working under the same misunderstanding

[Agriv8]

Oh bu66er not sure how but I have lost ign driver on pin 36.

looking throught robs pages there may be some other ones but how can i work out which if any are 12v drivers that I can use for my wasted spark.

Assuming i have blown a fet  next time I have the vems apart  i will solder a fresh on in will contact rob on monday and see if I can buy one.

regards agriv8

[rob@vems.co.uk]

It all depends on which option you had when you got the system:

Option 0 All 8 injection channels have logic level(+5v) control for coils that have built in igniters or systems where you wish to use an existing Igniter pack:


Option 2+6 Two channels are high current, the other 6 are logic level:


Option 4+4 Four high current channels, Four logic level:


Option 6+2 Six high current channels, two logic level:


Option 8 All 8 channels are high current control channels:

[Agriv8]

thanks rob,

got that printed in the garage but as I bought the unit second hand I dont seem to have any indication of which optoin has been chosen guess its just a case of finding a live one by sawpping the pins over.

regards

Agriv8

[rob@vems.co.uk]

I'd pop the case open and trace through which IGBTs are populated.

Chances are I'd pop the dead one out and move one of the good spares in its place.

[Agriv8]

So are the 5v logic drive IGBTs the same as the 12v one ?

If not how do I identify  12v IGBTs ?

Looking at the pictures it again pin 10 is a favorite if its populated.

regards

Agriv8

[rob@vems.co.uk]

The logic drive is provided by a wire jumper on the board, it doesnt have an IGBT connected and is current limited so not much danger of popping things with it.