camshaft position sensor code

CobraCommandr · Sep 6, 2011

hello,

i am having issues with the check engine light which keeps kicking out the CPS code p0340. i have done research on this problem and most people point to a bad alternator causing RFI feedback which is disrupting the sensor. this weekend i purchased a new alternator and CPS and am still getting the check engine light with the same code being thrown.

the car starts up just fine but when i accelerate, it struggles. it feels exactly like the firing order is out of sync. unfortunately i have double and triple checked the firing order to ensure this wasnt the case and still having the same problem. i did notice that the input from one of the coil packs to the PCM not solid but wasnt sure if this would cause this code to be thrown. i would think that i would get a miss fire code if the car had issues with the plugs or coils.

the car has 50k miles on it. any help or guidance you guys can provide is greatly appreciated.

thanks!
danny

CobraCommandr · Sep 7, 2011

anyone have a similar issue like this before?

wmburns · Sep 7, 2011

The usual cause of false P0340 DTC codes is a bad alternator diode. Since the alternator is new, we will assume this has been ruled out.

I'm going to assume that the battery holds a charge and that all battery cables are clean, tight, and corrosion free.

Any ignition issues especially spark leakage can affect other subsystems just as the bad alternator diode does. Are the radio interference capacitors in place?

There is a detailed procedure in the Ford service manual that if followed will positively isolate the problem. Unfortunately is in a format that can not be uploaded.

If you would like a copy of the Ford service manual, wiring diagrams, and PCM manaual, I maybe able to help. PM if interested.

Now on to the performance issue. Whenever there is a cam related DTC, the PCM is unable to tell the compression stoke from the exhaust stoke. The PCM responds by firing the fuel injectors on EVERY stroke. This results in twice as much fuel as required. This extra fuel can wash the cylinder walls and dilute the oil with gas. The result could be a ruined motor.

Never operate a motor with a cam related DTC for extended periods of time. This goes double for any modified application such as larger fuel injectors ect.

I'm positive that some of the performance issues are related to the motor drowning in gas. Fix the cam DTC and I suspect there will be noticeable improvement.

OBTW, it's a good idea to always post (or put in your sig) the model year of your car. I shouldn't have to read your other threads to find out this is a 1996 Cobra.

CobraCommandr · Sep 9, 2011

hey.. thanks for all the great info. so... i was able to fix the problem thankfully. it was a loose wire that was leading to the camshaft position sensor right behind the power steering reservoir. somehow, the wires that ran into the plug that connect to the cps had come lose and was not activating the sensor causing the error. i snapped the wire back into the harness and bingo! the cps was receiving power. needless to say, i now have new alternator and new cps. with the error cleared and not coming back anytime soon, the car is running much better. still probably needs new wires and plugs but that should be a nice project for the weekend. also, one of the coil packs ended up breaking due to age which was $50 to replace.

i will update my sig so that its clear what im talking about moving forward. thank you for your thoughtful response once again.

danny

camshaft position sensor code

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