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Discussion Starter · #1 ·
I am running a FAST XFI with Cherry Hall Effect Sensors for Cam and Crank. They are the red 12mm ones.
While my car is running at a consistent RPM I will get a false reading. At idle the reading will jump about 3k RPM.
Do I need to install a pull up resistor or anything in the wiring?
I wired it into a 12v source. Should I rewire it into a regulated 5v source?
 

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You need to check and see if they have a built-in pull-up or not. You also need to see if they can run on unfiltered and unregulated power. Normally they can, but check.

Most hall effect sensors pull the output low when a magnet is near, and either have an internal pull-up resistor or need an external one added.
 

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Discussion Starter · #3 ·
the spec sheet I have on it does not say regulated or unregulated but it can run on 5v - 24v
It also shows the resistor added in line. It is a common sensor everyone here has recommended and I have ran them without any resistors before but for some reason this one is giving me issues
 

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If they rate it from 5 to 24 volts, then it has a built-in regulator already. If you have a Radio Shack by you, you can probably get a 4.7K resistor to use as a pull-up. Wire it between the output of the sensor and the positive voltage coming in. See if this helps you.
 

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Just a thought, some hall effects are clock sensitive. Meaning they have to be orientated correctly to the passing trigger. Any that I have worked around will have a flat spot on knurled area. Look at the spec sheet. Or a more basic problem could be its just fucked up. Do you have any more to try? Manufacturing errors do happen.
 

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Just a thought, some hall effects are clock sensitive. Meaning they have to be orientated correctly to the passing trigger. Any that I have worked around will have a flat spot on knurled area. Look at the spec sheet. Or a more basic problem could be its just fucked up. Do you have any more to try? Manufacturing errors do happen.
Ha, Oh so true! :)

One of the Hall Effects I use al the time at the shop only works with the magnet "polarity" correctly. IE: It only "sees" a North or a South pole passing. I always forget which one, but I know how to install it so the Hall Effect works correctly.
 

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Discussion Starter · #9 ·
I have extras I can try. I will add the resistor first and see if that fixes the problem. Its not the easiest sensor to replace due to how my turbo kit is routed
 

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...Cherry Hall Effect Sensors for Cam & Crank. They are the red 12mm ones.
What's the sensor air gap adjusted to?
 

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If it runs OK and shows 3K or more wrong on the tach. Why do you guys Think its a trigger error. If it triggers 1 Point wrong in 1 RPM it will break up bad.

So is it external (tach) or is it also internal (log)?
 

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If it runs OK and shows 3K or more wrong on the tach. Why do you guys Think its a trigger error. If it triggers 1 Point wrong in 1 RPM it will break up bad.
That's a good point. Maybe it's just a laptop/ECU/Datalogger issue.
 

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Discussion Starter · #13 ·
If it runs OK and shows 3K or more wrong on the tach. Why do you guys Think its a trigger error. If it triggers 1 Point wrong in 1 RPM it will break up bad.

So is it external (tach) or is it also internal (log)?
It reads correct 95% of the time
 

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Discussion Starter · #17 ·
Just went out to work on the car and it is still doing it, I am thinking about putting in the holley 3/4 16 hall effect sensor
 

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Just went out to work on the car and it's still doing it, I'm thinking about putting in the Holley 3/4-16 Hall-Effect sensor
You'll have to change the target (trigger wheel) too.
Your (red 12mm) Cherry Hall-Effect sensor is a geartooth sensor, which senses a ferrous steel tooth target.
The Holley 554-118 Hall-Effect sensor is a magnetically operated sensor, which senses magnets in a target.
 

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Discussion Starter · #19 ·
You'll have to change the target (trigger wheel) too.
Your (red 12mm) Cherry Hall-Effect sensor is a geartooth sensor, which senses a ferrous steel tooth target.
The Holley 554-118 Hall-Effect sensor is a magnetically operated sensor, which senses magnets in a target.
I already have a flying magnet with the cherry sensor, we have ran that setup in other cars and cant figure out why it doesnt like it. I will be ordering the holley sensor this weekend
 
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