Hall effect reading double what I need

Thread Starter

Biffy

Joined Jul 27, 2022
2
Working with a crankshaft sensor analog Hall effect. It gives an rpm readout to computer of car. It is currently reading 2x what I need it to be. It has 8v dc supply ground and output. Can I adjust the input to effect the output
 

Ya’akov

Joined Jan 27, 2019
6,264
Well, the RPM is measured by counting the pulses not from an analog voltage level. Do you have any idea why your are apparently getting two counts per revolution? Does the ECU have some sort of configuration option for the sensor?
 

Reloadron

Joined Jan 15, 2015
6,822
Well, the RPM is measured by counting the pulses not from an analog voltage level. Do you have any idea why your are apparently getting two counts per revolution? Does the ECU have some sort of configuration option for the sensor?
This and my question becomes the make and model are correct for the computer you are reading from? Meaning the ECU and sensor are correct for the make and model? If the ECU is expecting 1 pulse per revolution and seeing two I would expect what you are seeing. Problems like this usually point to changes in things like sensors and ECU.

Ron
 

upand_at_them

Joined May 15, 2010
918
Are you sure that you're reading it correctly? The crankshaft rotates twice per combustion cycle, so you might be reading the signal incorrectly.
 

shortbus

Joined Sep 30, 2009
9,525
If you need to count a half speed use the cam sensor instead, the cam runs at half the crank speed.

What is this in, make and model or is this something your building?
 

shortbus

Joined Sep 30, 2009
9,525
Are you sure that you're reading it correctly? The crankshaft rotates twice per combustion cycle, so you might be reading the signal incorrectly.
Not sure where your getting that. RPMs are the speed the crankshaft is turning, has nothing to do with the combustion cycle, whether talking about 4 cycle or 2 cycle.
 

upand_at_them

Joined May 15, 2010
918
Not sure where your getting that. RPMs are the speed the crankshaft is turning, has nothing to do with the combustion cycle, whether talking about 4 cycle or 2 cycle.
I mean if he's reading or calculating is some odd way. If the sensor has only one pulse per revolution then he's doing something wrong. He hasn't shown or described anything so we can't assume he's got the "per minute" thing right.
 

MisterBill2

Joined Jan 23, 2018
12,696
If you are using a tachometer calibrated to trigger on ignition pulses for one cylinder, and instead you are using a crankshaft pickup, it will indeed read twice as high.
So let us know what sort of device are you using to display RPM. Also how many cylinders is the engine.
 
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