Hesitation/Bucking @ 45 MPH under very light acceleration

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skipppy75

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Been having this issue for a couple thousand miles now.
I changed the COP's last week and still had the issue, I just finished changing all the spark plugs and I am still having the issue.
At around 45 MPH I give the truck very light acceleration and truck vibrates/shutters and hesitates. I am at a loss on what to do next. Anyone have any suggestions? I have been searching all over this forum for answers but have not come across anything I think pertains to me after I just did the coil and Spark plug replacement.

This is a 2007 Expedition Limited with the 5.4 3V
 
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Bedrck47

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how many miles on the expy?
when was the last time the fuel filter was changed?
are you getting a check engine light or have you had the codes read?
 

jimp

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One of your coil packs might be bad. Do a lawn mower check or use a multimeter to check resistance (open or short bad, don't know spec. resistance but check many and one out likely the bad one.

Don't get caught in belt or get bit if doing the lawn mower check.
 
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skipppy75

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how many miles on the expy?
when was the last time the fuel filter was changed?
are you getting a check engine light or have you had the codes read?

currently just about 100500 miles
changed the oil, oil filter, fuel filter, coil packs,added can of Berryman B-12 Fuel treatment and higher octane fuel all at around 99800, second fillup added higher octane fuel also
no check engine light ever came on
scan guage II did not show any codes or pending codes
changed the spark plugs today around 100500 miles

issue was starting to be noticeable around 98k-99k miles not exactly sure
 
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skipppy75

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One of your coil packs might be bad. Do a lawn mower check or use a multimeter to check resistance (open or short bad, don't know spec. resistance but check many and one out likely the bad one.

Don't get caught in belt or get bit if doing the lawn mower check.


checked resistance before installing them and they all were about the same as the ones that I took out, reason why I did the spark plugs today thinking one may be fowled but with new plugs same issue as before
 

69Hcode

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Try running higher octane gas and see if that helps. Won't help your wallet but truck might run better.
 
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skipppy75

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I put the higher octane in and I also added a can of Berryman B-12 Chemtool fuel treatment to the fill up after doing all the work at 99800 miles and filled up one more time on higher octane before changeing the plugs but that did not help so that's why I changed the spark plugs. Still have about 5 gallons left in the tank after 2 fills of higher octane.

Really appreciate all the comments keep them coming, might have to break down and go to Ford to have them try to diagnose. I see a TSB AS-21769
"FORD: IF THERE IS AN INTERMITTENT LACK OF POWER, SURGE, OR HESITATION WHILE DRIVING THE BRAKES WILL OVERRIDE ACCELERATION."
Could this be my problem the hesitation shuttering is the brakes on light acceleration?

Wife just told me (guess she didn't think it was important while I was under the hood the last week) she had a surge when coming to a stop possibly, so I am thinking TSB #07811
"HARSH 1-2 AND/OR 2-1 SHIFTS, TIP-IN HESITATION OR SURGE, AND/OR LONG ENGAGEMENT TIME. "
I only see the light hesitation of getting going after comming to a stop but she said it surged on her.

Could all this be linked?
Anyone else have these type issues? I bought the truck used with 88k miles from a Ford dealer.
Is there anyone on here that can pull an oasis report? I was on a different forum for my Excursion (recently totaled) that I had one pulled and sent to me in 2008.
 
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Indyexpy

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Skippy75, your problem is identical to mine. 07 at about same mileage. I too was convinced it was the cop and plugs. Replaced the plugs cause it needed it anyway. And five of them broke...expected. That did not solve my problem. What DID solve the problem was changing the tranny fluid and adding a conditioner. It's pretty much a sealed tranny case and it's synthetic so I had thought it didn't get changed. Wrong. You gotta do this job just right or you can jack up the tranny, but my mechanic knew what he was doing and the problem is gone. I've since learned that this six speed box likes to have fluid flush and change approaching six digits on the odom. I'd give this a try with a good independent mechanic.
 

Dale

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I am having the same trouble with a 2005 set up like yours. I have replaced the Fuel Filter, Throttle position sensor, and #6 spark coil. The #6 was showing occasional misfire with extreme demand on throttle, and the new coil helped. Even though the mileage is around 110,000, the plugs that I pulled for inspection looked real good, clean, no soot or fouling of any sort. Mine's Hesitation/Bucking under very light steady acceleration, as in climbing, will happen anywhere from 40 to 60 MPH and sometimes even taking off from an intersection. My Autoxray scan tool shows the "cam duty cycle" takes a severe dive when the symptom occurs. Is "cam duty cycle" similar to spark advance??
I have a cleaner applied to the gasoline too now, but no help so far yet. Please reply if you make any progress.
 
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