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CPS testing results

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Old 12-05-2014 | 06:53 PM
  #16  
CCKen's Avatar
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Originally Posted by bigbadon
Oh well, I just ASSumed....guess I made one out of myself.

LOL

I've been there, done that.
Old 12-05-2014 | 06:57 PM
  #17  
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Originally Posted by Roler
Thats exactly what happened with the previous CPS, the chafed area, causing the wires/insulation to melt, so checked that but could not see or feel any similar going on now. Tied it away from the manifold anyway (sub-optimal designed routing , but easy fix).
Cleaned CPS - and camshaft sensor connections, checked grounds, checked all plugwires and the coil connections to be snug (last tune up about 12-15 000 miles ago)
Started it up yesterday, ran crazy rough and shaky even in idle and was dripping from the exhaust, smelled like petrol. Shut it off and left it. Went out again tonight, started up fine and ran fine.

Reeks of an intermittent electrical/sensor/connection issue on all sides, I'd say...
Perhaps you should look into a malfunctioning Camshaft Position Sensor, in that it's puking fuel out the tailpipe. If the CMP goes nuts the PCM won't know which injector to fire, nor how long to keep it open. Additionally, the PCM won't know which plug to fire and when.
Old 12-05-2014 | 08:21 PM
  #18  
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Originally Posted by CCKen
Perhaps you should look into a malfunctioning Camshaft Position Sensor, in that it's puking fuel out the tailpipe. If the CMP goes nuts the PCM won't know which injector to fire, nor how long to keep it open. Additionally, the PCM won't know which plug to fire and when.
Thanks Ken. I thought to mention that petrol drip, since that was new.
So,
1) it would do that with a faulty Camshaft position sensor and not so much with a bad Crankshaft position sensor?

2) and RA only has one camshaft position sensor listed, but that looks like one for a 2000. Do you mean the distributor pickup coil, that flat disk-like part with the connector wire?
Old 12-06-2014 | 07:47 AM
  #19  
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Originally Posted by Roler
Thanks Ken. I thought to mention that petrol drip, since that was new.
So,
1) it would do that with a faulty Camshaft position sensor and not so much with a bad Crankshaft position sensor?

2) and RA only has one camshaft position sensor listed, but that looks like one for a 2000. Do you mean the distributor pickup coil, that flat disk-like part with the connector wire?
1) The CMP is involved in fuel injection timing and dwell. The MAP Sensor is also involed in lean/rich activity. Not so much the Crank sensor.

2) Rock Auto lists them as a Distributor Pickup Coil, Chryler calls them Distributor Switchplates, and the FSM refers to it as a Camshaft Position Sensor.

OEM part number for a '97 4.0 is 56027023.

http://www.rockauto.com/catalog/rafr...%2BRSSW1402669&

Search Rockauto by part number 56027023, not by part description.
Old 12-06-2014 | 06:15 PM
  #20  
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I figured that part would have different names.
That's the part number I found in the parts catalogue and ordered one from RA
Replaced my MAP three years ago when CPS was done.
Old 05-31-2018 | 02:30 PM
  #21  
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Originally Posted by Roler
Got visited by an ol' friend again, the stalling/hesitating/bucking/coughing....the symptoms that were resolved 3 years ago by replacing the CPS (unknown brand).
I know that the symptoms can be caused by other things, but somehow I suspect the CPS again (for now)
So, got out and did the CPS testing procedure.
And now a bit stumped with the results.


When I connect terminal B and C (like this procedure tells you to), I get different outcomes.
When the black probe is on terminal B and the red probe is on terminal C, there is infinite resistance ("open"), which would indicate a good CPS (or at least for testing at not-warmed-up temps)
However, when I put the red probe on terminal B and the black on terminal C, I get a reading of around 500 on my multimeter (set to test continuity), which would indicate a bad CPS.

I'm not fully skilled in electrical testing at all, but as far as I know, continuity is not related to polarity. Why do I then get two different/almost opposite results? Am I missing something here?
There is a transistor inside the sensor, and transistors only let current flow in one direction until the voltage raises higher than the voltage on the other side of the circuit. Just look up how transistors operate and you'll get an idea. Polarity matters when testing transistors.

When the magnet in the crank sensor sees the shutter gap in the flywheel the magnetism on the transistor side away from the flywheel is reduced which will allow current to flow, at least that's the theory.
Old 05-31-2018 | 09:36 PM
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Old 06-01-2018 | 01:03 PM
  #23  
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But Interesting
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