Ford: 95 2.3 no start, camshaft position, crank sensor

Question
hi tim,
 i just installed a 97 2.3 ranger engine in a 95 ranger everything went fine done this a couple of times before..but when i tried to start it it would fire ok for 1-2 sec than shut off cleanly pulled code p0340 so replaced cam sensor also replaced crank sensor(oh joy)but still it starts for 1-2 sec than shuts off, if i give it gas it wants to run with some backfire and loops a lot,smells of rich gas. i used the 97 fuel injectors but swaped t/b to old motor since i knew it worked.still pulles code p0340 but voltage to sensor is steady at 5V and ohm is good is there anything you know of would cause this? i used a 97 motor since they are suppose to be identical
 any help would be most appreciated...Bob

Answer
Hello,

Cam sensors picking up stray electrical noise is a common problem.


1. Check the output of the Camshaft Position (CMP) sensor signal, to verify that it is outputting an AC voltage signal. The output will typically be 0.2 AC volts at idle and will increase with engine RPM.

2. Using a lab scope, monitor the signal for a uniform pattern and that there is no additional electrical "noise" on the signal of any sort.

3. If electrical noise is detected, disconnect the alternator voltage regulator to see if the pattern cleans up, check for faulty plug wires, a defective ignition coil, or radio capacitor at a coil pack.

4. If the sensor appears to be functioning OK, check for a jumped timing belt that would cause the cam/crank sensors to be out of sync.


You may also want to see if the PCM is the same 95-97