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persistent po1391 error

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Old 07-28-2020, 01:23 AM
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Default persistent po1391 error

1999 dodge ram 1500, 5.2, lifted 4x4.
Recently replaced engine, afterwards got po1391. Changed CPS, cleared was good for about 200 mile, got po1391, changed CPS, noticed wearing on front of sensor (16th inch). Figured I damaged flex plate mating up engine and transmission, changed flex plate, got po1391. Pulled sensor no rubbing. Changed sensor just in case of damage or faulty part. Got po1391. Set to TDC verified position on distributor, changed pickup coil (cam sensor). Started up, no DTC, turned off restarted, got DTC, got po1391 back. (Cleared DTC with OBD scan tool after each repair) Spar adv shows 1%, 6%, then 17% and it dies at idle.
At a loss, don't know what to try next. All I can think of now is take it to shop and have them put it on computer to diagnostic and see why their not syncing, but they charge $250 phr and said it could take up to 4 hr, and if its ecu its $275 to reprogram and if the ecu has faulty circuit, I'll need to by another ecu and have it programed,, in addition. I just feel its like giving a blank check,, and i dont have cash to spare these days.. Would an aftermarket tuner work..
Any thoughts would be appreciated
 
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Old 07-28-2020, 01:52 AM
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No an aftermarket tuner will not help and just add another variable. I realize this might not be of much help, but the correct way to diagnose the problem is to use an oscilloscope and monitor crank and cam position sensor waveforms. Having said that, many people have had issues with aftermarket sensors and recommend OEM only. Do you still have the old engine at hand and maybe can swap sensors ?
 
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Old 07-28-2020, 06:39 AM
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P1391 Intermittent Loss of CMP or CKP
What brand sensors did you put in? If you scanner reads live data you can see what it's missing either cam or crank sensor.
 



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