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A cam sensor idea I never expected to work, but it does...
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Author:  MadScientistMatt [ Fri Apr 23, 2021 11:58 am ]
Post subject:  A cam sensor idea I never expected to work, but it does...
I had been poking around to see if I could get a sensor in through the fuel pump port to read the fuel pump eccentric and serve as a cam position sensor. This was something that sounded workable but I figured I'd need to do a lot of work with a threaded sensor to adjust the sensor gap. But after a few measurements, I found that a Hall effect sensor we sell where I work happened to be just the right length.

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I just needed to drill and tap two holes in my fuel pump block off plate.

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View from inside the motor.

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I was able to confirm it triggers with a volt meter.

Image
Author:  Greg Ondayko [ Fri Apr 23, 2021 12:45 pm ]
Post subject:  Re: A cam sensor idea I never expected to work, but it does...
Good tips there Matt,

Thanks for sharing.

I will probably "borrow" / recycle that approach some day.

Greg
Author:  DadTruck [ Fri Apr 23, 2021 6:58 pm ]
Post subject:  Re: A cam sensor idea I never expected to work, but it does...
Nice tip Matt, can you post a part number and source ( DIYAUTOTUNE?) for that sensor?
Author:  Greg Ondayko [ Sat Apr 24, 2021 4:21 am ]
Post subject:  Re: A cam sensor idea I never expected to work, but it does...
Quote:
Nice tip Matt, can you post a part number and source ( DIYAUTOTUNE?) for that sensor?

Most likley This one

Greg
Author:  Dart270 [ Sat Apr 24, 2021 11:23 am ]
Post subject:  Re: A cam sensor idea I never expected to work, but it does...
Wow, super cool! I will likely use this on Project V as I wire up the MS3X soon.

Lou
Author:  MadScientistMatt [ Mon Apr 26, 2021 12:51 pm ]
Post subject:  Re: A cam sensor idea I never expected to work, but it does...
Correct, it's the sensor in Greg's link.
Author:  Badvert65 [ Mon Apr 26, 2021 1:48 pm ]
Post subject:  Re: A cam sensor idea I never expected to work, but it does...
It would be interesting to see what the pulese looked like on a scope, especially whit the engine running.
Author:  emsvitil [ Mon Apr 26, 2021 5:30 pm ]
Post subject:  Re: A cam sensor idea I never expected to work, but it does...
Quote:
It would be interesting to see what the pulese looked like on a scope, especially whit the engine running.

Yep.....

Doesn't seem like it would have a distinct enough signal because of the gradual change in distance from the sensor.
Author:  MadScientistMatt [ Tue Apr 27, 2021 6:43 am ]
Post subject:  Re: A cam sensor idea I never expected to work, but it does...
Quote:
It would be interesting to see what the pulese looked like on a scope, especially whit the engine running.
Since this is a Hall effect, the waveform will be a 0-12 volt pulse once per cam resolution - I was able to confirm it transitions properly in a low speed test, although it's possible you may get a few noise pulses at the edges. The real question will be how stable it is. The MS3 with a missing tooth crank trigger allows for a lot of tolerance on the edges - even if these change by 60 degrees or more, you can still get a stable enough reading in the center of the lobe.

Once I have the engine running, I plan to use the VVT mode (intended for cams with hydraulically adjustable advance) to see if I can get a read on how stable the trigger edges turn out to be.
Author:  Greg Ondayko [ Wed Apr 28, 2021 7:17 pm ]
Post subject:  Re: A cam sensor idea I never expected to work, but it does...
If one planned on using a cam for this explicit purpose a more finite edge could be ground into that pump lobe if needed correct?

Greg
Author:  Dart270 [ Thu Apr 29, 2021 3:22 am ]
Post subject:  Re: A cam sensor idea I never expected to work, but it does...
Yeah, good idea. Could be done by hand with a die grinder or even bench grinder.

Lou
Author:  MadScientistMatt [ Thu Apr 29, 2021 7:23 am ]
Post subject:  Re: A cam sensor idea I never expected to work, but it does...
Quote:
If one planned on using a cam for this explicit purpose a more finite edge could be ground into that pump lobe if needed correct?

Greg
Yes, but this should work fine for anything short of putting a hydraulic VVT actuator on your cam sprocket or attempting to data log your timing chain stretch.
Author:  Greg Ondayko [ Thu Apr 29, 2021 7:30 am ]
Post subject:  Re: A cam sensor idea I never expected to work, but it does...
Quote:
Yeah, good idea. Could be done by hand with a die grinder or even bench grinder.

Lou

Yep, Fo' SHo'


Greg
Author:  Greg Ondayko [ Thu Apr 29, 2021 7:31 am ]
Post subject:  Re: A cam sensor idea I never expected to work, but it does...
Quote:
Quote:
If one planned on using a cam for this explicit purpose a more finite edge could be ground into that pump lobe if needed correct?

Greg
Yes, but this should work fine for anything short of putting a hydraulic VVT actuator on your cam sprocket or attempting to data log your timing chain stretch.

Sounds good Matt,

Good luck with the initial drop in and fire up!

Greg
Author:  emsvitil [ Thu Apr 29, 2021 4:09 pm ]
Post subject:  Re: A cam sensor idea I never expected to work, but it does...
I may be wrong, but don't most ECU ignore the cam position sensor once they've already figured it once during start.......

So if the signal is good enough during starting for the ECU to figure out where the engine is in it's cycle, you're good to go.
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