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Truck Jerking/Studdering Around 45-50 mph

 
  #121  
Old 11-20-2013, 10:51 PM
Bluegrass 7
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traildad, quite a learning experience with the right scanner to look into the program and see these things...no?
The mode 6 test will even tell you when the boots are getting bad, moisture is getting in, what cylinder might be causing radio interference etc.
FORD designed the system to be able to trouble shoot it to a very fine degree with FORD's test equipment.
What 'you'/'we' cannot do for example is send operating commands to the PCM to request it do functions then see the expected results. This is when you can see failures in the systems.
Unfortunately the faulty coil issue was never planned on for easy finding unless mode 6 is accessed and the cause/effect known other than by luck.
Many dealer service departments won't let the techs spend the time to chase issues by this method or the techs don't know how or not allowed to go to go beyond the code level.
When this is the situation, service is often poor on difficult troubles.
Good luck.
 
  #122  
Old 11-21-2013, 10:54 PM
traildad
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Well I replaced the #5 coil yesterday. I had to clear the codes to get the misfire count to reset to zero. After that the #2 cylinder showed a low # of misfires but still OK. Today on the way home from work it did the bad misfire again. I rechecked and #2 showed zero and #5 showed some misfire but still OK. So I guess the coil was not the problem or the new one is bad also. I checked the plug when I changed the coil and the gap was OK, the plug was white and I saw that I installed Autolite plugs about 30,000 miles ago when I first had the misfire problem. I didn't see any carbon tracking or other problems. I guess I can swap the #1 coil for the #5 and see what happens.
 
  #123  
Old 11-21-2013, 11:10 PM
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Before you change any more parts use the trap function to freeze the data and see what it tells you.
Good luck.
 
  #124  
Old 11-24-2013, 07:54 PM
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Hurrah!!! Got my stumble cured on 4.2 V6. Replaced the coil pack as suggested in thread. Stumble actually got worse.

Have 88K miles so it is close to the plugs and wire maintenance scheduled change. Next replaced plugs and wires. The stumble is gone. I will not let the spark plugs go more than 50K miles in the future.

Just letting you folks know what cured my problem. Sure am thankful we have a son that is willing to help on these issues.

 
  #125  
Old 11-25-2013, 01:52 AM
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Change the spark plugs and wires. If still there change the coil pack.

Worked for me.

 
  #126  
Old 11-26-2013, 07:37 PM
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I moved the #1 coil to the #5 spot. I put the old coil into the #1 spot and it missed bad enough to throw a code for #1. I put the new coil back in and the miss went away. For the last couple days neither #5 or #1 is missing. This tells me that the problem is not plugs or fuel injection. Now I just need to see if it comes back over time. What I do find is a miss in #6 and #8. The misfire test still says ok for them, but it does show a miss. Is this normal to have small misfire readings come and go? Or is this a sign that those coils are nearing the end of their life and will soon fail?
 
  #127  
Old 11-26-2013, 08:35 PM
Bluegrass 7
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Your coil issue is one of shorted turns as explained.
Yes you can see some low misfire counts on various cylinders but if they do not cause an obvious code (below the radar) activity or drivability issue ignore them or just keep a watch as a matter of education.
Some times boots cause the low misfire counts, sometime the relative humidity or both when 10,000 volts or higher is involved in a closed space..
Don't let it annoy or concern you because you can't often have a perfect zero count for all cylinders all the time.
When you have the ability to see all this sometimes it is overdoing it.
To keep chasing it beyond a no code level is spending money and time for perfection you may no be able to achieve.
.
The system is capable of detecting many faults on an intermittent basis.
The driver alerts or CEL and codes to all this have been 'pulled back' or the vehicle would be in the shop all the time for every little detected issue.
This is one reason some dash gauges have been dumbed down to simple indictor positions that never change.
Example is the oil gauge. It stays the same at all times and never moves with changes in oil pressure because it is 'switch' activated.
If people knew it only is an indication of pressure above about 8 psi they would be concerned but a needle that shows good is all that counts to the average owner or driver..
Good luck.
.
 
  #128  
Old 12-19-2013, 08:07 PM
Rich164
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Bluegrass, thanks for sharing your wisdom. My 97 Dodge Ram is doing the same hard jerk that you speak of at 45-50 mph. However, I think the Dodge only has a single ignition coil. Does it still make sense for that to be the problem? Thanks for any advice.
 
  #129  
Old 12-19-2013, 10:01 PM
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Not being familiar with your control system it sounds like the same type of issue.
If the misfire is only in that speed range I would assume its for much the same reason as most vehicles operate overall nearly the same.
Most of the mfgers are doing the same general type of control, driven by the need to control oxides of nitrogen during that part of the drive cycle time where the motor spends most of it's time.
The intent is to cool the combustion temperature down to reduce this emissions level as dictated by the federal EPA..
This is done by introducing exhaust gas back into the intake. (EGR)
Since exhaust does not burn the second time it leans the air to fuel ratio in a different way so the combustion is not as hot.
When this is done the coil voltage needed is higher.
If the ignition is not up to firing the leaner mix reliably, you feel it as a shudder/misfire during that specific driving situation.
Additionally the reason a properly operating system is not normally felt as a drop in power is because the ignition timing is advanced and fuel cut back making up for the change in conditions during that time. It has to be done this way for technical reasons and to be transparent in operation.
Many mistake this fault for transmission trouble in a Ford but in another make it could be the transmission depending on the way the system is designed to work.
In a FORD, under this OD condition, the converter is normally locked up into direct drive so no slip should be possible in a fault free transmission.
If there is a trans. fault it should be felt in other gears and speed ranges as not an engine fault..

Good luck.
 
  #130  
Old 12-19-2013, 10:15 PM
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Thank you Sir for the rapid response. I guessed it was transmission originally and paid a shop to look at it. They charged me $100 to "diagnose" and supposedly add fluid. Obviously, that didn't fix it. I'll replace the ignition coil and then work back towards the distributor if that doesn't work since that's the cheapest easy access option for my elementary capability. Thanks again, much appreciation. Will buy Ford next time.
 
  #131  
Old 12-21-2013, 09:04 AM
Rich164
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Hey Bluegrass, replacing the ignition coil on my Dodge didn't fix the 45 mph jerk. It hasn't done it again if I turn the overdrive off though. I guess I'll change the plugs and wires next? Do you agree? Thanks again.
 
  #132  
Old 12-27-2013, 06:07 PM
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replacing plugs and wires fixed it. thanks again for the advice.
 
  #133  
Old 12-27-2013, 08:33 PM
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Good to hear you solved the issue.
It was still ignition related but a different color horse.
A plug with eroded tips and or a wire with high resistance that lowers the voltage trying to ignite a lean mixture results in the same end result as on Ford systems. Remember what you have is much worst than a coil over plug system on the Ford.
It goes like this; coil fired transfers spark across the rotor to cap 'gap' then through the plug wire resistance plus any leakage along the way to the plug where it has to provide the spark Kernel to begin the combustion event.
Ford moved to the coil over plug system to eliminate all those losses in the old systems like you have.
There may be another very important difference between the two systems.
In your's the coil may be powered up and down for each cylinder's use.
This would limit the 'dwell' time the coil has to saturate it's core with current flow each time.
.
On Ford's system or any other cop system the coils are powered full time such that the power is removed only at time of sparking.
Note the ignition timing is derived in this manner by controlling the ignition timing event by spark delivery points before top center being the final ignition timing [for each separate cylinder] every time.
The full power on time results in full saturation of the coils with plenty of time to spare.
The benefit is higher voltage available at all times for a very lean mixture, a very rich mixture and high rpm operation over all those dynamic operating ranges. All this affecting the combustion outcome being more uniform under a wider set of conditions and a cleaner running motor.
Add to this the Ox sensors fuel control keeping the mixture within tighter limits.
You can see these results in a fault free engine by looking at the spark plug tips and porcelain. They are normally quite clean and whitish causing some people to think the motor is running lean or the plug heat range is to hot when it is a normal condition.
This fine a control you normally can't attain with a carbed motor.
As Paul Harvey would say; Now you know the rest of the story and why the Ford motors most often run several hundred thousand miles as opposed to the old push rod motors that have significant wear at 100k..
Isn't computer controlled fuel injection wonderful?
Good luck.
 
  #134  
Old 12-30-2013, 04:03 PM
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Been reading up on all the posts of the shudder and bucking at 40 to 65 and feels like one of the same issues im dealing with would this also give a p0442 or a p0401 ?
 
  #135  
Old 12-30-2013, 08:37 PM
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A 402 code could be implicated but not a 401.
The shudder involves the EGR system when it is operating during that time.
A 402 code indicates the PCM diagnostics has detected a leak in the EGR tract into the intake when tested for flow during idle.
A faulty coil can react to this during cruise conditions as an excessively lean condition the coil can't fire on that cylinder.
The result is a shudder feeling from one cylinder that comes and goes with driving conditions.
Good luck.
 

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