2002 Ford Escape Misfire on rough running engine. No CEL

Tiny
RMURDOCK
  • MEMBER
  • 2002 FORD ESCAPE
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 156,000 MILES
Greetings:

Using a coil on plug tester, Cyl #6 appears not to be firing and #4 randomly firing. I swapped #6 Coil and plug with #5 (the working cyl) and the problem stayed with cylinder #6.

I checked wiring continuity all the way back to the ECM. No opens. No shorts.

There is no check engine light. The front bank cat melted which also clogged the downstream cat. Replaced both and am now trying to deal with the underlying problem of the cylinder misfire.

QUESTION:

Does this sound like an ECM problem? Why would the ECM single out one cylinder; and how does the ECM know when a coil is failing enough to throw an error code?

Could a failing camshaft or crankshaft position sensor affect a single cylinder?

Any ideas would be greatly appreciated.
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Wednesday, May 26th, 2010 AT 9:47 PM

8 Replies

Tiny
RASMATAZ
  • MEMBER
Hi rmurdock, Welcome to 2carpros and TY for the donation

Could a failing camshaft or crankshaft position sensor affect a single cylinder? Could be and the ignition control module to include the computer coil driver no.6
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Thursday, May 27th, 2010 AT 1:51 AM
Tiny
RMURDOCK
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Greetings:

I am not clearly understanding your answer.

Are you saying that a camshaft (or crankshaft) positioning sensor COULD indeed affect the #6 cylinder while not affecting the #5?

If so, then how can that be? It seems to me that the sensors are triggered by interacting with a single spot on their respective wheels. For example, looking at the camshaft positioning sensor with the valve cover off, it looks like there is a single spot that co-incides with the #1 cylinder only. Which begs the question, how could that affect the #6 cyl and not the #5. I suspect that I am missing how the whole timing process works.

ALso, are you suggesting that it MIGHT also be the PCM? If so is there any test I can run to confirm?

I have ordered a cheap oscilloscope online. I was planning to measure the pulses at each cyl from the PCM. That test would still not rule out a camshaft sensor if indeed, a camshaft sensor could affect the #6 cyl only.

Please clarify and add any further tests that you think would prove fruitful.

Thanks for your response.
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Thursday, May 27th, 2010 AT 10:57 AM
Tiny
RASMATAZ
  • MEMBER
Swapped coil/plug with no.5 and still don't work check the coil driver circuit from the computer and also the CPS

The CPS has a timing wheel that detects the position of the pistons and tells the computer what cylinder coil to fire. Same goes to CMH sensor what injector
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Thursday, May 27th, 2010 AT 3:56 PM
Tiny
RMURDOCK
  • MEMBER
Greetings:

1) COIL DRIVER CIRCUIT
OK, how to I 'check' the coil driver circuit? Isn't that buried somewhere inside the ECM?

2) CPS
When I looked at the camshaft sprocket, I only saw 1 magnetic spot (Cyl 1) that the CPS would sense. Are you saying that there are 6 magnetic spots that the CPS would sense, thus one for each piston?

Further, since the CPS would be common to ALL of the cylinders, how then could a failing CPS affect only the #6 cylinder?

3) CMH
I am not familiar with this acronym. What is a CMH?

Please advise and please address all three of these questions.

Thanks
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Thursday, May 27th, 2010 AT 5:45 PM
Tiny
RASMATAZ
  • MEMBER
CMH is the camshaft position sensor is use at times to synchronize the injectors

) COIL DRIVER CIRCUIT
OK, how to I 'check' the coil driver circuit? Isn't that buried somewhere inside the ECM? Correct and this is where your problem is coming from-Remember you swapped coil/plug and its a no-go-Replace the computer I know its not cheap I'm trying not to take you here but this is were we stop.
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Thursday, May 27th, 2010 AT 5:59 PM
Tiny
RMURDOCK
  • MEMBER
If CMH is the camshaft positioning sensor, then what is the CPS? I had been referring to the camshaft positioning sensor as the CPS.

Also, what about my question regarding whether or not the camshaft sproket had 6 magnetic positions or just the 1. If it has 6 then I can understand better how the firing works. If is has only 1 then it is a mystery to me as to how it knows when to fire #6.

Further, how then could a failing camshaft positioning sensor which sees all 6 positions in the same fashion have an affect on #6 and not #5.

Please advise.

Thanks.
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Thursday, May 27th, 2010 AT 6:06 PM
Tiny
RASMATAZ
  • MEMBER
Don't matter if it has one or 6 is how the system works -The CPS senses it by 120deg of crankshaft rotation reports this to the computer in turn it fires the coil. If you're unsatisfied please! Request for a refund
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Thursday, May 27th, 2010 AT 6:12 PM
Tiny
RMURDOCK
  • MEMBER
All I wanted was a clear explanation.

If that is beyond the scope of this service then please accept my apologies.

I wont bother you again.
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Thursday, May 27th, 2010 AT 6:14 PM

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