can anyone tell me how much voltage should be going threw the crank sensor? and how much should come out off it?

my cam sensor sends a nice clean 5 volts.
but the crank sensor sends 1.5 to 2 volts and its very eradick(sp)
if this is in the wrong section please move it.
thanks in advance, matt

 

Are you reading the voltage with a multimeter?? I believe it produces its own on/off digital voltage signal. Therefore your multimeter will average the voltage its getting. The signal should be a 5 volt output when on and 0 when off. So it will read 2 or so when running. Someone correct me if im wrong.

 

if its a good meter, aka fluke, you can use the min/max setting to read it better

 

You could just turn the key on and roll the motor slowly by the crank pulley and check that the volts go from 5 to 0 over and over .

 

If it was 50% duty cycle and spinning much faster than the meter could sample at it should read 2.88675. Right?

Voltage/sqrt(3)

 

The crank sensor is a "hall effect" switch. 12 volts, a ground and a signal circuit.

 

How are you measuring the voltage? I assume with the ignition ON (engine off) and the connector disconnected from the sensor.

 

loose reluctoir on the crankshaft. time for a stroker crank, lol. put a motor in it. in all reality, take the sensor out and see if you can move the reluctor around with a screwdriver. and the PCM gives it 12 volts, like goat cheese said, not five, and it works on the electro magnetic principle, not hall effect. ( there is a difference between hall effect and inductive pickup)

 

the pan is off relutor is tight.
crank is callies...hmmm
voltage is right. it runs minimal seems out of time,
most of the time wont even start.


things replaced,
ignition msd
wiring harness,coils wires, cam sensor, crank sensor,
coils.

starting to think reluctor is off a few degrees.
does anyone know what the air gap should be for crank sensor?

thanks again

 

Have you checked reluctor runout? The note in the box with my Eagle says that it has to be verified and it has to be less than .020 or else it won't run.

 

any codes? remember, not all codes will turn the MIL on. what have you done since it last ran right? it might just need a CKP learn done on it( i kinda doubt it though if it will barely run) a ckp learn takes like 30 secs with a tech 2 if everything else is right. got any friends at a gm dealership?

 

Never knew there was a difference. I always thought "hall effect" was just another descriptor for inductive pickup. They both use the interuption of a magnetic field for frequency interpretation no? Or maybe the difference is that a true hall effect switch goes to zero volts on the signal lead, and inductive pickup simply reads an interference in the field?

 

The reluxor isn't magnetic but ferrous. The hall effect is a magnet.

Hall effect could be useful for something moving both ways. Reluxor can't. Relux probably puts out a smaller signal. Not sure on that one. Only ever used IR or light sensors.

 

Right, and that is how the crank sensor works. 12V through a ground circuit creates a magnetic field, as the reluctor teeth pass by, the field is "disturbed", and that frequency is sent through the sensor circuit. What I am confused on is if a true Hall effect switch is only considered a hall effect if the sensor signal pulls down to zero or not.

 

That makes sense.

If you have a magnet passing through the sensor the magnetic field makes electric force perpendicular to the field. I would think that the voltage would swing from even higher to even lower as you increase the speed of the wheel. Hard to program the computer to look at that. In that case it would be more convienent to look at the frequency or clicks for second.

In this case I guess the best bet is to just check the reference line and make sure the other lines have good continuity.

 

theres no codes
it has an msd stand alone ignition. there is no factory computer at all.
this is in a track only car.

it ran fine with my 346. i built a new 408 and it dont run.
i used the same sensors,and also tried others.
we did a square wave signal last night and every thing seems right.

every thing works ...just wont fire at the plug.
gonna try and call msd...
im thinking if the reluctor is out of sink with the cam it wont fire????

 

Have you confirmed voltage at the PCM side sensor connector with the ignition ON (no cranking)? If you're getting voltage, but not to the ignition coils, check the fuse box for continuity.

 

so what interfaces the factory sensors with the msd box? what msd box are you using?

 

i believe the reluctor is off.
callies says if i had the ability to do a crank relearn
that would probably fix it, but i dont with the msd,
so i sent the crank back today for inspection

stay tunned should know more in a few days

 

Even if the stock vehicle needs a crackshaft position relearn it will still fire and run.

You would think the MSD will still fire also, just at the wrong time.