Ford Signature PIP signals

Hello,

I am working on a project and I am going to be reading the signals from a Ford TFI distributor with the Signature PIP. The distributor has a vane cup that passes by a hall effect sensor. One tooth on the vane cup is smaller than the rest to identify that cylinder # 1 is at 10 degrees Before Top Dead Center (BTDC). The regular vanes have a %50 duty cycle, the smaller one has a %35 duty cycle

What I am trying to do is have the Arduino read this signal and be able to register the difference between the small vane and the rest. This would be easy if the RPM were consistent. As the RPM is going to be varying, the width of the signal would also change.

How would I be able to get the Arduino to recognize the small vane? I was thinking that it would compare the last few it registered with a new one and if it was smaller by a significant enough amount that would be the smaller vane.

How about some pictures or links to see what you are looking at. Hard to see from here.

Paul

the first picture shows the output at some RPM, hence the consistency of the pulse width.
The second shows the actual cup that rotates around the hall effect sensor.

2009-08-07_203626_3.gif

Got it! Thanks. I see the narrower pulse is not centered, but has the back end cut off early.
A very rapidly changing RPM could make any one of the normal pulses appear to be a shorter one.

PAul

Could you us 2 sensors spaced exactly 2 or 3 PIPs apart? If a PIP was off when it should be on, it's the narrow one.
Knever mind, that wouldn't work.
Where does the engine RPM pulses come from? Knowing RPM, you know the pulse width of the PIPs, then look for a shorty.

I reread your original post and see an error. You state all the pulses are the same, except the short pulse. Again, under + or - acceleration, that will not be true. All the pulse widths will be changing and none will be identical.

Paul

outsider:
Could you us 2 sensors spaced exactly 2 or 3 PIPs apart? If a PIP was off when it should be on, it’s the narrow one.
Knever mind, that wouldn’t work.
Where does the engine RPM pulses come from? Knowing RPM, you know the pulse width of the PIPs, then look for a shorty.

On the early sequential fuel injection engines the only way the computer knew the rpm was through the hall effect on the distributor.

Now I believe the leading edges of the Vanes is equal distance from the last leading edge. So the RPM could be calculated by comparing the time between rising edges.

Could an expected pulse width be determined using RPM and if its shorter than the expected width (with a slight margin of error included in the program) it would be the small PIP?

Have a google for auto labs and megajolt. There is explanation on how this works with the Ford Edis module which outputs a similar type signal