TJ Crank Position Sensor Question

[jonah]

Does anyone know the which pin does what job on the the TJ cps? I need to hotwire one, most seem to be signal wire in the middle with power and ground on either side.

I am guessing there is some way to figure it out by measuring resistance between the pins but I am not sure what to look for.

Thanks!

[aw12345]

Crank sensor should be hall effect sensor. 5 volts power a ground and a signal wire. signal would be on or of 5 v or 0 v

[6spdYJ]

According to the Haynes manual,
Pin 1 is the output to the powertrain control module - it should be Grey and Black.
Pin 2 is ground and is Brown and Yellow.
Pin 3 is your 5V supply from the PCM and is solid Orange.
If you apply 5V to pin 3 and ground pin 2, you will see no output from pin 1 until you flag it with a piece of steel. You will then see your 5V. If you hit it with 12V, you'll see smoke. For the record, pin 2 will be in the middle.

[aw12345]

Jonah to get this thing to fire you need to power the ecm which needs to powerup the asd and fuelpump relais , which only happens when it sees a crank signal from the crank sensor. To get 5 volts to all the sensors the ecm needs to be powered up unless you have a sensor simulator that can put out 5 volts

[jonah]

Thanks for the info guys. I need to put a trigger wheel on Opey to get a clean signal for my fuel injection. I think my control box wants a 12v signal as it normally runs off the tach signal. So I think I am going to have to use a different hall sensor. I have found one that runs off 12v. I mostly wanted to use this one because it was readily available, oh well.

[aw12345]

Hall effect out of a distributor should work, you would have to make your own tone wheel or find a distributor that fits in there that uses a hall effect sensor to trigger the module

[jonah]

Yes it would normally work. I have HEI that puts out a signal that runs my tach just fine, however there is something going on with the ECU. I think it is due to one of two things. First could be that since the motor is an odd fire V6 the odd pattern of the signal is confusing the ECU. Or my second theory is that since the ECU is made for a V8 and it is running a V6 the ECU is calculating the rpm incorrectly. I have a feeling my second theory is correct and the ECU thinks the motor is running at 3750 when it is really running at 5000. I am having trouble with it leaning out too much at high rpm. My old analog FI system ran ok off the tach signal although even with that one I would get an occasional lean problem but I could tune it out. Anyway if I crank up the map to get the top end to run right it is too rich at idle. My theory is that at 800 rpm the ECU would think it is at 600 (small difference) but as you rev it up the gap becomes larger and you can't skew the fuel map enough to compensate. It the crank trigger doesn't fix the issue I will probably upgrade to a more sophisticated controller and that will need a crank position sensor anyway.

[aw12345]

Does your controller have a tach output? that would prove your second theory in short order. The odd fire issue probably doesn't help it none. Do they sell a crank speed sensor for this setup?

[jonah]

No tach output, it is the super basic Holley Projection 2D. I have been using to old analog Holley and it worked pretty well, but the newer digital one can run in closed loop so I thought it would be nice when going up into the mountains. I guess the newer digital box is more sensitive to the signal. It could very well be a combination of both issues. Either way the CPS and trigger wheel should eliminate the problem. The 12V hall sensor is ordered and should be here in a week or so.

I am also thinking of throwing the closed loop system on it and see if it can compensate enough when running in closed loop. Right now I have it tuned so the air/fuel is 12.3 to 1 at idle and 16 to 1 at 4500 rpm. So it isn't too far out of range. This motor seem to like running between 13.5 and 14.5 to 1.

[aw12345]

14.8 is supposed to be , just get he O 2 sensor to toggle rich lean nicely

[jonah]

Yeah, that is supposed to be the ideal for fuel efficiency but it feels like it makes a little more power when it is a touch rich. But that is just seat of the pants. Hopefully it will be sorted out soon, I am dying to get out.

[aw12345]

Yeah, that is supposed to be the ideal for fuel efficiency but it feels like it makes a little more power when it is a touch rich. But that is just seat of the pants. Hopefully it will be sorted out soon, I am dying to get out.

Get er done, Curtis wants to get us in all kinds of trouble on Sunday

[jonah]

Believe me, I noticed that thread. I would love to be out there to see what the big jeeps can do but my Mom is coming in from the east coast so I am not going to be out there. Hopefully there will be some good pics/vids. Unless I can convince my Mom to go jeeping....hmmm.

[vwtipeii]

I wanna go!! will need to be shotgun though ;(