I have a 2004 Dodge Dakota SLT w/ a 4.7 Magnum that ran really rough, and had build up on one of the spark plugs. While doing a compression test we had found that one of the cylinders had 0 compression, the other 7 cylinders seemed to be fine. Instead of trying to diagnose the issue and later rebuild the engine we had just decided to swap out the engine from a donor vehicle.

The donor was a 2003 Dodge Durango SXT w/ a 4.7 Magnum. We finished putting everything back together today but when we tried starting it, it would crank, but wouldn't turn over and actually start. We checked to see if the computer was throwing any codes and we had gotten P0335 for the Crankshaft Position Sensor.

Any help getting this thing to start would be much appreciated.

 

Check the number of 'teeth' on the tone ring the crank sensor reads. (both motors. Should match, probably don't.)

 

I just found out this was a thing about an hour ago. I'm reading different things stating "If the 8th digit in the vin says N then it has the 32 tooth." in both VINs the 8th digit/letter is N, so they both match there.
However I'm also reading somewhere that says if the PCM is a 3-plug it's the 16 tooth. If the PCM is a 4-plug it's a 32 tooth. The Dakota has a 4-plug and the Durango has the 3-plug. So I'm thinking it is the Tone Ring.
Is there any other way to tell without pulling the engine back out?

 

Nope, you got it. NGC controller versus JTEC controller. Incompatiable. Junkyard should have made you aware of this when they offered the engine, should be a major note in the interchange manual that they do not interchange across years.

 

I didn't get it from a Junkyard, I bought the Durango from a guy off of OfferUp. He sold it because it had a bad transmission, it wouldn't shift past 1st.
I'm thinking if I go and swap the 16 Tooth Tone Rings with the 32's it should work fine as you need to make sure your camshaft tone ring goes with the correct crankshaft tone ring with the correct PCM.
Could that work?

 

It will work, but you have to pull the crankshaft out of the block to change the rings.

 

My understanding is its part of the crankshaft meaning to swap means pulling the engine apart.

So no not a simple easy thing to do.

 

Yes, the engine has to come apart.