efi A Cam Position Sensor design - please critique

[AustrianVespaGuy]

I'm just gonna leave this here while I contemplate if it's worth the $$ to give it a go, but seems to check all the boxes! 60mm threaded M8 body and rated up to 140 degC. . . !!!

 

https://www.automationdirect.com/adc/shopping/catalog/sensors_-z-_encoders/inductive_proximity_sensors/8mm_tubular/dw-hd-621-m8-100

[jimk]

1 hour ago, AustrianVespaGuy said:

I'm just gonna leave this here while I contemplate if it's worth the $$ to give it a go, but seems to check all the boxes! 60mm threaded M8 body and rated up to 140 degC. . . !!!

 

https://www.automationdirect.com/adc/shopping/catalog/sensors_-z-_encoders/inductive_proximity_sensors/8mm_tubular/dw-hd-621-m8-100

Save your money.

If that style is preferred, get a Cherry

Edited July 14 by jimk

[AustrianVespaGuy]

9 minutes ago, jimk said:

If that style is preferred, get a Cherry

Can't though, cause the cherry only comes in M12 rather than M8, and machining out the hole in the head surely costs more than the $100 different in sensor price. Unless you know of an M8 Cherry. . . but I haven't been able to Google one up yet

[TobyB]

AVG, have you checked yet to see how consistent the detection threshold is for these switches?

 

It would suck to get this physically perfect to discover that you're getting a 20 degree timing scatter

from sensor detection variability...

 

t

 

[AustrianVespaGuy]

22 minutes ago, TobyB said:

It would suck to get this physically perfect to discover that you're getting a 20 degree timing scatter

from sensor detection variability...

 

Naw, it's a non-issue provided you're ONLY using it for the cam phase detection.  We don't actually care about true cam position here, we just need to know 'are we on #1 intake or #4 intake stroke?'  Add to that the fact the most ECUs only even check for this cam signal at/right after startup and then once you're 'locked-in,' it no longer matters until the NEXT startup, so even if you lose the cam signal while running (changes/drops out at higher RPM), it's all still good. Important things like spark and injector timing are all still calculated based on the CRANK position signal, and so for *just* phasing even +/- 40 scatter doesn't really matter.  There is still the *slight* possibility that the wandering cam pulse occurs at EXACTLY the same time as the missing tooth gap in the crank signal - which would be bad - but even then we have some ability to work around that problem by just swapping between rising-edge vs. falling-edge trigger in order to 'move' the cam pulse further away from where the gap is.

 

Now if you're trying to deduce engine speed/position and/or need actual cam position like for variable valve timing, then yeah it probably wouldn't work at all.  But for the 99% of M10 builds here with a missing tooth crank wheel just interested in running sequential, I think we're pretty darn safe.

[jimk]

1 hour ago, TobyB said:

AVG, have you checked yet to see how consistent the detection threshold is for these switches?

AVG could install the sensor and continue to run semi-sequential until the cam signal is scoped and set up.

 

By adjusting the gap to the pump lobe the switching point of switching might work to adjust signal trigger time.

[TobyB]

oh, duh, right- the earlier pictures of distributors with shutter wheels got me all confuzzled.

 

t

 

[Dudeland]

7 hours ago, AustrianVespaGuy said:

 

Naw, it's a non-issue provided you're ONLY using it for the cam phase detection.  We don't actually care about true cam position here, we just need to know 'are we on #1 intake or #4 intake stroke?'  Add to that the fact the most ECUs only even check for this cam signal at/right after startup and then once you're 'locked-in,' it no longer matters until the NEXT startup, so even if you lose the cam signal while running (changes/drops out at higher RPM), it's all still good. Important things like spark and injector timing are all still calculated based on the CRANK position signal, and so for *just* phasing even +/- 40 scatter doesn't really matter.  There is still the *slight* possibility that the wandering cam pulse occurs at EXACTLY the same time as the missing tooth gap in the crank signal - which would be bad - but even then we have some ability to work around that problem by just swapping between rising-edge vs. falling-edge trigger in order to 'move' the cam pulse further away from where the gap is.

 

Now if you're trying to deduce engine speed/position and/or need actual cam position like for variable valve timing, then yeah it probably wouldn't work at all.  But for the 99% of M10 builds here with a missing tooth crank wheel just interested in running sequential, I think we're pretty darn safe.

Does this hold true for MS3’s .  In terms of setting the cam timing on startup?

[AustrianVespaGuy]

3 hours ago, Dudeland said:

Does this hold true for MS3’s .  In terms of setting the cam timing on startup?

Absolutely, and for Haltech and Fueltech, and I assume AEM though can't say for sure. I think all will throw a 'cam sync' error if you DO lose the signal while running to notify you, however I'm also pretty confident that none will drop back OUT of sequential once synced up and going. Once you 'find' that first phase, from then on it's as simple as just counting crank rotations.

[veronatii]

I've been running my cam sensor on the fuel pump lobe for a couple months now with reliable results. I have my ECUMaster classic configured to only use the sensor during startup, then rely on the crank position afterwards. Before setting it up like this I found that at higher RPM (~5000) the spring wouldn't return the fuel pump shaft quick enough, and the cam sensor signal got all jumbled. 

[AustrianVespaGuy]

12 minutes ago, veronatii said:

I've been running my cam sensor on the fuel pump lobe for a couple months now with reliable results.

Which sensor and how do you have it installed?

[AustrianVespaGuy]

 

Oh, this contraption, with the washer, spring, and set screw?

On 3/13/2024 at 2:28 PM, veronatii said:

Here's where the spring will fit. I have a stiffer spring on the way with an 8mm ID and should fit nicely. Total rod movement is about 4mm.

 

[veronatii]

2 hours ago, AustrianVespaGuy said:

 

Oh, this contraption, with the washer, spring, and set screw?

 

Yep but it’s just a spring and a cotter pin now

[Dudeland]

Someone should make a cam position sensor that bolts into where the fuel pump lives.  If you are using efi, then you don’t need the pump.

[AustrianVespaGuy]

. . . Yeah that's exactly what we're working on here, with the long pole in the tent being a sensor that can survive the environment. Once I validate that though. . .