'96 Taurus Vulcan P0340 replaced CMP code still there

[atlanticbluejetta]

On my '96 Taurus Vulcan I had the squeaking cam synchronizer and code P0340. I replaced the assembly in the same position (vane and housing) as the old one, but the P0340 returns. What should I check next?

[shorod]

Is the squeaking gone?

-Rod

[shorod]

Per the factory service manual:

Possible causes:

-- CMP circuit open.

-- CMP circuit shorted to GND.

-- CMP circuit shorted to PWR.

-- SIG RTN open (VR type).

-- PWR GND open (Hall effect type).

-- VPWR open (Hall effect type).

-- CMP Sensor (Hall effect type) not installed correctly.

-- Damaged CMP Sensor.

-- Damaged PCM.

Sounds like it's time to grab the multimeter and verify the wiring.

-Rod

[atlanticbluejetta]

Yes, the squeaking is gone. I read somewhere on the internet that interference from a bad DPFE sensor can cause a P0340. I know this is a common part to fail and as far as I know the original is still on the car. There is a slight surging during acceleration. Thanks for your help.

[atlanticbluejetta]

I swapped in another DPFE sensor from another Taurus and the P0340 still comes back. I checked power to the CMP sensor-has power, checked ground-yes, checked signal wire for continuity to computer-good, checked for pulsating signal from CMP when turning engine over-yes. The only things left are bad computer or cam synchronizer installed incorrectly. I was very careful when I installed the synchronizer to put it back as the old one. The only odd thing is that the old synchronizer seemed OK (except for the squeak), tooth was undamaged, sensor looked OK. Hope it's not the computer.

[shorod]

I'm not sure if this will be any consolation, but when I was working on cars at my dad's shop (over 13 years ago) I don't remember ever replacing a Ford ECU. Having been involved on this forum for 6 years I can't recall more than one post suggesting someone needed a new ECU. We did, however, find several faulty GM ECUs, and there were several options for rebuilt GM ECUs. We didn't have many Chrysler ECUs either that failed, their ECU issues seem to be pretty recent (late '90's and early 00's). So I wouldn't place an order for a new ECU/PCM just yet.

-Rod

[serge_saati]

Originally Posted by atlanticbluejetta

On my '96 Taurus Vulcan I had the squeaking cam synchronizer and code P0340. I replaced the assembly in the same position (vane and housing) as the old one, but the P0340 returns. What should I check next?

I have a similar problem just yet with my Taurus 2002 OHV. I replaced my cam synchronizer with CMP sensor 3 months (3500 miles) ago because a squeaking sound (no CEL). The noise never come back.

But today, just after I started the engine, CEL appeared. So I check code and I have P0340 (Camshaft position sensor circuit range/performance). I read that it's a 2 trips detection logic to activate P0340 during cranking. So sensor misses at least 2 consecutive times.

But engine runs well, no misfire, no problems. Could it be just an intermittent detection problem or low voltage detection in cam sensor? Could the car have chances to stall suddenly or misfire because of that?

How did you fix your issue atlanticbluejetta?

[atlanticbluejetta]

Sorry, I can't help you. I erased my cel after it came on after I replaced the cam sensor and it has not come back. Good luck.

[serge_saati]

Ok, I reseted the engine codes just after the problem. Now I made 350 miles and the CEL didn't come back. So It was just a glitch with the cam sensor when I started it up last time. It's not a real problem.