Triger Wheel on a SOC

[RTR75]

Glad to see this site.
This has probably been gone over before so if it has please excuse me, the other forum is gone.
Can the trigger wheel (36-1)be mounted to the cam and do away with it on the crank?
Will you be able to run sequential?
How would it be wired?

[stevieturbo]

It's a good question, and I believe it should be able to work. But I dont know how to configure it.

[RTR75]

I found a 2" wheel that would be able if fit at the end of the cam, all tucked inside and then just the sensor sticking out.
But how to wire it???

[Roverdose]

cam runs half the speed so you'd need a 2 gap trigger wheel, with gaps opposite each other.

the cams are connected by belt/chain on most engines so a little vibration in the running gear and you may not get exactly the right timings.

also the cams dont rotate freely, the lobes make the movement quite jerky, so the signal may also be a little rough.

sounds possible but its not as exact as a crank trigger.

Drew

edit, had a think on it!

[Wally]

Because the cam runs at half speed of the crank I very much doubt you will get a reliable signal at cranking speed.

Wally

[RTR75]

Verry ture, fogot about your points.
Got to wraped up in looking a dead head tring to make it fit, oops
but still would be interisting
So for my racing engine its staying on the crank!
Thanks
Linc

[stevieturbo]

Nissans optical trigger on most of their engines is the only trigger. Some Toyota engines are the same, albeit with a mag trigger. As are many Hondas.
Although all of these models use a multitooth for rpm with no gaps. And a secondary trigger inside the same housing for phase.

So there certainly is no need for using a crank trigger ( although it is the preferred way ) and if all those manufacturers do it, I wouldnt be overly concerned about any accuracy issues.


Still dont see why it would need 2 sets of missing teeth though ? There is only one no 1 TDC, which is ultimately the only thing the ecu needs to know as far as a missing tooth goes.

[Roverdose]

if he was using it as a crank trigger.

if he sets it up as a cam signal only then one gap would be fine.

Drew

[RTR75]

Never mind …thanks all
If I would just read some of my old books that I got from GM years ago. You need both to run sequential.
Once the engine is running and the ECU sees the cam signal the first time, the cam sensor does nothing! Take it out through it a way... The ECU needs to know exactly which one is number 1 cylinder when the crank is at TDC thus the use of the cam position sensor.
So in short to answer my own question….yes you can run a 32-1 wheel on the cam but it will work only as a cam sensor and you will still have to run a crank sensor!
As I tell all my techs...RDFM before you ask me a dumb question!

[stevieturbo]

You do not need both to run sequential.

But most ecu's will require both. Doing what you suggested fills all the criteria for a sequential system. But that doesnt mean the ecu you are using will accept it.
The missing tooth will still indicate the exact position of No1 TDC, and the other teeth will provide the crank angle position reference ( because it is directly related to cam angle )

But if the chosen ecu isnt happy with it, then it wont work.

And some systems will ignore the cam trigger once synced up. Others will always check for it's reference.