Chrysler Repair: 1995 Stratus, camshaft position sensor, o2 sensors

Question
Hi Roland,
About a week ago you answered a qustion i had about a 1995 Dodge Stratus that stalls after it heats up. Your suggetion of the erg valve and o2 sensors were cheked out andi found the egr to be functioning, it only has one o2 sensor after the cat (which leads me to believe its not the origional exhaust system), all to no avail. I also installed a new ignition coil as that was an error code that presented. I did however today check the spark coming out of the ignition coil itself to the plug wire both when engine was cold(the car runs perfect in this temp condition) and spark was strong, but when the car stalled after warming up for about 15 min., i rechecked spark out of the coil and it only had spark at the #1 and #4 cyls. Nothing was coming out of 2 and 3. This is very indicitave of how the car "chugs" when in this "stalled" condition, as i can keep it chugging like this if i quickly flutter the throttle.   ( I dont do this for long mind you, i know its not good for the engine). My question is this, being a distributorless ignition system, are the only two components involved here the PCM and the ignition coil(which I have eliminated as the culprit. That would leave only the PCM. Your insight would be greatly appreciated. Thanks, Dan

Answer
Hi Dan,
No, the decision as to whether to fire 1 and 4 vs. 2 and 3 is determined by the camshaft position sensor on the rear of the engine at the camshaft. I conjecture that it may be failing as it heats up. You can check out the difference in the voltage pulsing it exhibits using a digital voltmeter placed between the tan/yellow and the black/dark blue wires by probing those wires at the sensor (piercing the insulation with a fine straight pin), turning the ignition key to the 'run' position, and then cranking the engine over by hand using a socket and handle on the crankpulley bolt. Normally the voltage will change from 5v to 0.3v and back to 5v and then 0.3 for every two revolutions of the crank (the timing of the changes is not symmetrical, which is how the pcm knows whether the cam is ready for the 1-4 or the 2-3 pulse. So if you observe the pulsing cold vs the pulsing when the engine is "chugging" and you see a degradation then that would be a good basis for replacing that sensor.
Are you sure there is no oxygen sensor on the output flange of the exhaust manifold? I would believe that all manifolds for that engine are equipped with a threaded port for the sensor.
Roland