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Firing issue, maybe cam or crank sensor?

S

SJon85

Veteran CEG'er
Joined
Sep 11, 2009
Messages
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So I thought that the reason for my rough running 3L was because of the tune, but after a couple new tunes from NPG Joey told me that there is something going on with my spark. I guess the spark is all over the place and is dropping from 24 to 1 degree while cruising, which makes perfect sense because thats exactly how it feels while driving it. He suggested to check my PCM grounds, and the cam and crank sensors. With the key in the on position there is no power in any of the four wires at the cam and crank sensor, should there be? Also where are the PCM grounds?

I am also curious what the foil and extra steel wire is for that wraps around the crank sensor wiring?
 
the crank sensor wires are shielded, that is the extra foil and steel around the wires.

I'm not sure if the sensors should have power or not with the key on.

the PCM ground is on the passanger fender, and it comes off the pcm connector.

do you have the coil pack grounded? is that ground also clean?
 
Coil pack is grounded to one of the bolts on the rear valve cover. PCM ground has never been touched and looks fine.

Also if either the cam or crank position sensor was bad the car wouldn't even run, right? I think it has something to do with the wiring for the crank position sensor as it looks like the harness I just got from a guy locally has the crank sensor soldered into it. So how do I test this wiring? Or do I just find another harness.
 
Im pretty sure the base edis timing (with no pip signal, aka no timing information coming in from PCM) is 10* so the fact you are dropping to 1* definitely points to the fact something is whack. Have you tried a new ignition module? It takes the Pip signal from your PCM is the device that actually is deviating the timing.

There will be no power to magnetic reluctance sensors like we have. Our crank/cam position sensors create their own voltage, while cranking it can be anywhere from 2-4volts. The faster the wheel/trigger is turning the more voltage is created, I have heard up to 100 volts on some applications. So these have to be moving to see the voltage. You will need an oscilloscope to see whats going on with these sensors. They work on AC voltage and you will need to examine what your cam/crank signal is behaving/looking like. The scope measures the voltage mapped over time, so you see your actual waveforms that your car is deciphering. My first guess would be that it is the cam sensor. If there has been after the fact wiring I would check polarity on your sensors. Another good application for the scope. I dont know if these cars would run with a backwards crank sensor, but I know most cars do run with a backwards cam sensor but obviously poorly. If you were triggering on the wrong edge (-ve) if may be causing your issues. You can test the polarity by observing which way the voltage jumps when metal passes the sensor. Goes up then down your triggering on +ve edge goes down then up your triggering on -ve and it is backwards.
 
2000ZxT said:
Im pretty sure the base edis timing (with no pip signal, aka no timing information coming in from PCM) is 10* so the fact you are dropping to 1* definitely points to the fact something is whack. Have you tried a new ignition module? It takes the Pip signal from your PCM is the device that actually is deviating the timing.

There will be no power to magnetic reluctance sensors like we have. Our crank/cam position sensors create their own voltage, while cranking it can be anywhere from 2-4volts. The faster the wheel/trigger is turning the more voltage is created, I have heard up to 100 volts on some applications. So these have to be moving to see the voltage. You will need an oscilloscope to see whats going on with these sensors. They work on AC voltage and you will need to examine what your cam/crank signal is behaving/looking like. The scope measures the voltage mapped over time, so you see your actual waveforms that your car is deciphering. My first guess would be that it is the cam sensor. If there has been after the fact wiring I would check polarity on your sensors. Another good application for the scope. I dont know if these cars would run with a backwards crank sensor, but I know most cars do run with a backwards cam sensor but obviously poorly. If you were triggering on the wrong edge (-ve) if may be causing your issues. You can test the polarity by observing which way the voltage jumps when metal passes the sensor. Goes up then down your triggering on +ve edge goes down then up your triggering on -ve and it is backwards.
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You're knowledge is WAY over my head!! The ignition module? So there is an additional module outside of the pcm is what you're saying? I never had any problems like this with the old harness, now I just added the newer harness and I am now having this problem that seems to be the wiring in the harness, which makes sense because the wiring on the crank sensor has been messed with. Beans is hooking me up with a brand new harness for a good price, so hopefully that does the trick.
 
no, the ignition module is built into the PCM on these cars and very rarely every goes bad (with the exception of the 95s which DO have a separate ignition module). If you want to verify the wires are in the correct pins on the connector, both the cam and crank sensors use the white wire on pin 1. the connector should be labeled as to which one is pin 1, but if you cant find it (or cant read it) when you are looking in the end of the connector (with the wires) with the clip on the top pin 1 is usually the farthest to the left. however, the Ford CD doesnt have the pins labeled which leads me to believe that the PCM doesnt care which pin is which.
 
Have you tried pulling out the Camshaft Positioning Sensor while the car is running, to see what happens?
 
The cam and crank sensors have been replaced at this point with no changes
 
I understand - but I am asking if you have the car idling, have you unplugging the cam sensor? And what happened?

I am curious because of an issue I am having with my car as well. Technically, the car is supposed to QUIT running - but mine doesn't. It runs perfectly when I do that, so I was wondering if I have a one-hit-wonder here, or if this is a clue to what might be wrong.
 
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