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Stumbling 4.6L

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Old Dec 2, 2010 | 07:55 AM
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Stumbling 4.6L

I have a 2003 with a stubling 4.6
this is acting line when I change the elbow on the back of the manifold. But that is ok.

the only codes are a 308, and 300.

It is also hard to start in the morning. Any ideas where to start?
150K miles

thanks
doug
 
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Old Dec 2, 2010 | 08:30 PM
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Verify the fuel pressure
 
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Old Dec 3, 2010 | 10:02 AM
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Originally Posted by blackestate
the only codes are a 308, and 300.
Cylinder #8 (back one on driver's side) is misfiring. That's the reason for the stumbling.
 
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Old Dec 3, 2010 | 10:26 AM
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Originally Posted by blackestate
the only codes are a 308, and 300.
P0300 is multiple cylinder misfires - that's why I'd verify the fuel pressure, as the fuel pressure effects all cylinders, just like the elbow on the back effects all cylinders.

On the other hand, Alloro is usually right . . . . .
 
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Old Dec 3, 2010 | 10:39 AM
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Originally Posted by pdqford
On the other hand, Alloro is usually right
Not according to my wife!
 
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Old Dec 3, 2010 | 12:08 PM
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Originally Posted by alloro
Not according to my wife!
Sounds normal.
 
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Old Dec 3, 2010 | 11:16 PM
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Me too, What should the fuel pressure be? And I am assuing I check it at the test port on the line that holds the injectors
 
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Old Dec 4, 2010 | 02:31 AM
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Originally Posted by blackestate
What should the fuel pressure be? And I am assuming I check it at the test port on the line that holds the injectors
About 45 PSI and yes you test it at the fuel rail as you described.
 
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Old Dec 7, 2010 | 05:09 PM
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fuel pressure is 43. Seems to run better after running it hard but it now comes and goes.
I was thinking I would replace the PCV valve, Can you tell me where that is? Also after I reset the codes, it has not had any come back, but has a few moments where it stumbles, then runs fine. Also when it stumbles there is no power, and if you floor it, and get to about 60, it starts running fine again?
Thanks for the help so far.
 
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Old Dec 7, 2010 | 06:12 PM
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Originally Posted by blackestate
I was thinking I would replace the PCV valve, Can you tell me where that is?
Top middle of the passenger side valve cover.
 
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Old Dec 7, 2010 | 07:50 PM
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I pulled that hose and it is just a fitting on the valve cover on both sides.
This is a 4.6 if that matters.
Thanks
 
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Old Dec 8, 2010 | 07:02 PM
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Engine Performance problem 2003 Ford Expedition V8 Two Wheel Drive Automatic
 
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