I had my 5.2 engine replaced about 1000 miles ago with a reman. Since that time, it has been raising a P1391 code - intermittent loss of camshaft or crankshaft position sensors.

Engine runs great at all speeds.

Ok, easy I thought. I replaced the crankshaft sensor first, becuase it appeared to not work when i manually turned over the enginer while back-probing the sensor. No dice.

I then replaced the camshaft sensor. No dice.

Both sensors are getting the 5V in, so now I am stuck.

Am I looking at an intermittent short possibly? One intersting thing I noticed. In 2 recent trips to Florida, the code would clear after a day or so driving there. Once I returned to Ga, it comes right back. Thought maybe it was due to heat or humidity that is affecting the wiring.

Anyone have any ideas?

Thanks,
Randy

 

Update - here is more info:

98 Dakota with 5.2 - had a remanufactured engine installed about 1000 miles ago. Truck runs great at all speeds.

Code P1391 has caused Check Engine light to come on pretty much since the new engine was installed.

This is an intermittent loss of camshaft or crankshaft position sensor. Here's what I have done so far:

1. Replaced both sensors.
2. Rewired the sensors from the PCM to the sensor connectors.
3. Reset the PCM by disonnecting neg terminal and turning key on for 30 seconds - Check engine comes back on after 10-15 miles.
4. I have rung out all wiring from sensor to PCM and it is good.

Still no luck - still runs fine, but I have to get the emissions done soon and need to clear this up.

Questions:
1. Am I clearing the PCM correctly?
2. Is there anything I need to do to clear the memory of the PCM for a new sensor?
3. Is there any way to check if the PCM is bad?
4. What else could be causing this?

Any help appreciated.

Randy