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Truck Jerking/Studdering Around 45-50 mph

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Truck Jerking/Studdering Around 45-50 mph

 
  #46  
Old 08-19-2012, 01:09 PM
F150&EB
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Thanks to everyone who contributed to this thread! I experienced the dreaded shudder yesterday in my 02 SCREW with 105k miles and immediately thought I was in for a transmission rebuild. Found this thread last night and managed to get the Service Engine Soon light to flash this morning on the way to Advanced Auto to pick up a new Motorcraft coil. Back at home, my code reader picked up a P0302 code (misfire on #2 cylinder.) 15 min under the hood and she's running like new again.
 
  #47  
Old 09-13-2012, 11:22 AM
s9bryant
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Rockauto

Originally Posted by Boydp View Post
You know I need to add one more thing. Rock Auto.com were GREAT!!! I ordered the parts, went cheap on the shipping (3-day). The parts were here the NEXT DAY!!! The price was real good. Thanks to all who contributed their knowledge, It save me a bunch.

Bp
For those who have purchased the coils at Rockauto, can we be sure it's the right part : {#3W7Z12029AA} and genuine MotorCraft?
 
  #48  
Old 09-16-2012, 03:13 PM
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For those who are reading this thread, the shudder under the..."specific conditions"....is never the transmission.
It's in OD and converter lockup or a hard a drive train.
The transmission is electric control so there is nothing going on in the transmission but a static condition.
Any shudder or skip is the engine missfire.
When the missfires occurs the ignition timing goes retarded to make it more intense yet.
 
  #49  
Old 09-16-2012, 03:22 PM
Bluegrass 7
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Remove due to double post.
Internet drop out at time of reply and you don't know what you have.
 
  #50  
Old 10-20-2012, 06:24 PM
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I have the same thing happening to my 2001 F150 5.4L with 122k on the clock but only after she sits for a few days and it has been humid or rainy....
Hate to start the coil hunt and figure I might as well replace all 8 at this point!
Informative thread.

is this the right one?
Alternate/OEM Part Number(s): 3W7Z12029AA
MOTORCRAFT Part # DG508
$41.79 at Rock Auto
 
  #51  
Old 10-23-2012, 10:21 AM
tabbygirl
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I am in the same boat, I think. I have a 2002 f150 5.4Triton over 150k miles. I know nothing about trucks but lately I have had jerking problems. After about a month of jerking, it finally did it so bad the chekc engine light came on and I had a slight misfire and a hard misfire. All plugs were changed at the same time. It ran ok for about a week. I decided to change gas, still jerk. But it will not do it everyday nor at the same time nor at the same rate of jerk. Yesterday morning, REAL bad. Drove to shop that afternoon and it ran smooth and showed no codes. This morning, only one small jerk. I drive in a lot of traffic to and from work. My mechanic is nice and don't want me to spend unnecessary money if it is not the coils. I am thinking about biting the bullet and spending the money.
 
  #52  
Old 10-23-2012, 01:03 PM
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Had same problem on my 01 5.4. bought coils off ebay changed coils and plugs and now she runs like new. even with 190k
 
  #53  
Old 10-23-2012, 10:43 PM
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Again, you either have to get 8 known good coils in or find the one causing the issue.
I can explain why the plug change only lasted a short time.
I can also explain what the faulire is and why but would it mean anything to you?
It's a lot of typeing to do so.
Good luck.
 
  #54  
Old 10-24-2012, 04:01 PM
tabbygirl
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Thanks Bluegrass-

I finally figured out how to drive and make it start jerking (at least it worked this morning.) If I drove and feathered the gas pedal several times between 45-55mph, it would eventually start jerking when it needed power to climb a hill. Hopefully I can make it do it again on the way home and report this to my mechanic.
 
  #55  
Old 10-24-2012, 09:10 PM
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  #56  
Old 10-24-2012, 11:36 PM
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taby, you have one coil with shorted turns.
It won't set a code because it's not a hard fault.
The shutter comes when you get the motor into the speed range at light throttle that opens the EGR.
When the EGR opens the air/fuel ratio becomes very lean.
It's at this point the cylinder with the shorted coil (shorted turns) will missfire.
The violent jerking is one step beyond a missfire.
The computer actually stops processing all functions just like shutting ignition off and on rapidly until you get out of the specific area where this all begins and the computer recovers processing again.
Good luck.
 
  #57  
Old 10-25-2012, 04:22 AM
hotwater6
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Saw a new post and it reminded me that I forgot to reply with results.
I had the same issues with jerking/studdering (a few pages up). Replaced passenger side coil pack (no coil overs) for #3 misfire with only slight improvements. Went ahead and changed plugs and wires to find carbon tracking on #3 plug. Problem solved (but with more crawling around under the hood than I had hoped for).
 
  #58  
Old 10-25-2012, 04:22 PM
mctour
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Same problem

I have the same problem with my 2002 F150XLT 5.4L 4x4, had to turn off the overdrive.
 
  #59  
Old 10-27-2012, 12:13 PM
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Note the large number of hits on this subject.
It's a wide spread issue.
Here is what the cause is.
When you get in an OD light throttle drive condition, the EGR opens.
At this point the air/fuel ratio goes very lean "by design intent".
This condition requires the coils to offer higher voltage they "are" designed to give.
If a coil developes shorted turns in it's winding the voltage available drops to a marginal or below level.
This causes a missfire on that cylinder as long as this driving condition exists.
.
As soon as you downshift, increase engine RPM or make any throttle up or down change that takes the EGR out of operation the missfire goes away.
It goes because the air/fuel ratio has richened to the point the faulty coil now has enough voltage to fire the cylinder reliabily such as going from OD to third gear.
Most often this coil condition does not set a DTC code because it comes and goes and in not a 'hard' fault. Once the fault conditon in not present, the record of missfires to set a code is cancelled so no code or CEL is set for you to see.
.
Finding the cylinder at fault.
Four ways;
1. To sub a known good coil in each position until you clear the missfire.
2. Replace all coils but you always have the possibility of a faulty coil in the replacement group.
3. Use a Scanner with a Trap function to freeze frame the live data while drivieng.
4. Have a dealer do a Stress test on all the coils to pick out any that are below limits.
.
Plug replacement:
Sometimes new plugs seem to clear the issue only to return several hundred miles later.
Why;
The new plugs are easier to fire by a 'marginal' coil until their tips begin to errode then the required voltage begins to rise and missfire lightly begins all over again. Yes errosion begins that quick with new plugs.
Bottom line is this kind of issue is quite dynamic and complicated involving several parameters that 'stack up' to cause the end result of studder and missfire.
It can get so bad the faulty coil can send interference back to the computer causing it to stop processing any engine data until it recovers.
This feels like the ignition was tuned off and on at a fast rate, a 'bucking' feeling.
And no, its not the transmission doing any of this.
Good luck.
 
  #60  
Old 12-13-2012, 09:41 PM
rsylvstr
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thanks...I'm biting the bullet and replacing all the coils.
Shutting off OD doesn't help.
It does it only after sitting for a few days and after it warms up (dries out??) everything is fine. It does it from idle all the way through the powerband....
will update in a few weeks.
Plugs and boots/springs only have 20k on them.

was just reading another thread in the V10 section...might check the boots first...(sigh)
I have a two year old, i don't have time for this LOL.
 

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