P1391
 

I've read some on the diagnostics of problems I've had lately so this is what I have going on.
the distributor has been indexed properly while diagnosing a previous no start issue. Spark tested by pulling each plug one by one while running, replaced ngk 02 ,champ plugs and she is running very well.

99 auto recently swapped in a rebuilt engine from a 92.
.Ive ohm tested the ckps as good.
both ckps/cmps are 1yr old Mopar dealership sensors.
.99 flex plate was used
.napa echlin cap&rotor
.ignition coil, ohm test was good there is a fine hairline crack on the ouput side and I plan to replace this anyway.
.distributor is stock and had 220000 before I pulled the old motor.


the engine is running well, I have no noticeable effects driving, just that the scanner shows this p1391 unconfirmed code which comes back after it's cleared.

cmps hasn't been tested as I do not have an analog meter nor a osiliscope though I don't think this is likely the issue. I have gone through the fsm from cruiser site with no luck on any other diagnostic tests.
If I test ground pin on cmps harness am i probing battery negative and which ever terminal?

is there a good chance that the distributor has seen enough wear to be finicky? Gears worn?



Thanks for your help folks, lots of p1391 threads that people abandon and there's no resolve or diagnosis, they haven't been helpful. I will be following here with updates of any findings or fix, just need to know where you suggest looking next.