Code P1391, loss of CAM or Crank signals?

METZ1025

MEMBER
2002 DODGE RAM
4.7L
V8
4WD
AUTOMATIC
220,000 MILES

I swapped out the intake manifold since the old one cracked. Throwing no codes on truck before switching out manifold. The truck turned on for first time code P1391 came on and the truck is sputtering. Bouncing back and forth between 800 to 400 RPMs between idle. So, I swapped out the crankshaft and camshaft position sensor. Same issue of sputtering still happening. Checked harness and getting 5v per harness, checked for any fraying all the way to PCM and all looked good. Checked IAC and wasn’t performing well so swapped out IAC and TPS. I checked for vacuum leaks, and all was good. I unplugged crankshaft sensor still same symptoms. When I unplugged the camshaft sensor truck ran smoothly, no sputtering happened and RPMs stayed steady at idle. Any advice to figure this out will be appreciated.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,772 POSTS

Hi,

I don't feel replacing the intake itself caused a problem. I suspect there is a wiring that may have been damaged or disconnected.

First, (and I assume you have) check the connectors at the camshaft and crankshaft position sensors. Make sure they are in good condition.

Also, make sure there is nothing that may be pinched between the manifold or engine block.

If you look below, I attached the diagnostics for this code. Take a look through them and let me know if you are comfortable performing them.

Let me know what you find.

Joe

See pics below.

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