Autonerdz forums

Shay,

Post your question and maybe someone can.  It was not clear to me what you were asking in your link.

If you were asking if you could measure VVT advance with a two channel scope, the answer would be yes.  You would monitor CKP and CMP, then force the VVT to activate.  Then you could measure the degrees of change and the time it took for the cam phaser to move the cam.

Shay,

You would really not have any need to use trigger at all.  Just increase your capture time so you can see the entire event on one screen.

With a PicoScope, you can do that 

Dave,

Being a Honda Tech for ten or so years, it was nice to see that in action.  Was that done with the new Pico software?  Maybe not, cause of the mouse movement?  Either way, Nicely done.

Ed

Hi Ed

The capture was made with the latest Pico software at the time, although the animation is created with a different application. Pico's own software does allow you to create a basic animation, however you have very little control over the output. (you won’t get random mouse cursors though in Pico’s own animations )

Hi Bill

In the capture, we can see the crankshaft position signal in blue & the exhaust cam position is represented in green. The red signal that can be seen to shift, is taken from the intake camshaft sensor.The "stretching" effect that can be seen on the blue & green traces, is caused by the change in engine speed, in response to the inlet cam shift.

The engine control system has a dual method of control over the intake camshaft. The V-Tech system gives control over the intake valve lift & duration, by introducing a more aggressive secondary cam profile at higher engine speeds. The second means of control is by regulating the angle of the intake cam, in a manner that we are familiar with from many other manufacturers. A de-phaser pulley is mounted on the intake camshaft & this allows the control unit to regulate the angle & overlap of the inlet valve.

In the animation, we are activating the de-phaser pulley, by independently energising the oil pressure regulator solenoid, which diverts an increased oil pressure to the de-phaser pulley. The shift in the red (intake cam) signal demonstrates that the command has been acted upon. This is capture does not indicate that the V-Tech mechanism is functioning correctly.

Regards

Dave

Just to clarify Toms point....

Although my capture demonstrates nicely the close up view of the cam & crank relationships, it is possible to see the same effect, by cranking up the the "collection time", so that you capture many seconds of data.

With a two-channel scope, if you were to scope the exhaust cam (which has a fixed relationship with the crankshaft) & also the intake camshaft, you would be able to achieve a similar result, by zooming into the detail at various points in the capture.

If I am totally honest though, I think two channel scopes are too limiting in today's workshops. For a quick look they are fine, but when you need to study things a little deeper, then you will often need four channels (& often wish you had more).

As Tom has said many times before, any scope is better than no scope, but you will soon realise that the extra investment in four channels was worthwhile.

Cheers all

Dave

I was confused myself, Dave... have you said that the animation was inconclusive; that you cant verify that it is a bad phaser from the capture?

Dave,
Could you post the psdata file if you still have it?

Bill