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Truck Jerking/Studdering Around 45-50 mph

 
  #226  
Old 03-26-2017, 09:05 PM
iziggby
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Intermittent miss check your compression cylinders 4 and 7 perhaps, drive it into the ground with ring seal if you dont want to replace the engine, you cant fix two cylinders without the others going toast, you can put over 100K more on it by doing the band aid fix if you dont have the money to swap out engines or put in a reman or crate engine it all depends on how much you want to spend, me Im for buying a low miles good used and swapping out or at least Im about to right ordering my engine tomorrow.
 
  #227  
Old 05-16-2018, 09:54 AM
lalat
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Bluegrass:

So I'm new to this site....I'm trying to repy to your thread...Hopefully this is where I write:
I have the problem described below...jerking at 40-50 MPH. My truck was in the law suit with the spark plug problems short time ago. Can this problem be fixed with the spark plugs or is it the coil pack. Spark plugs are not that old. Not even 2 years old. Do I take to dealer &. tell them it's the coil pack or should just check the spark plugs?
Originally Posted by Bluegrass 7 View Post
Now it's time to listen.
You have at least one low output coil.
Again, here is the reason you have the miss.
At speeds between 45 and 60, the EGR system opens and causes a very lean air to fuel ratio.
This come about because the program that calls the EGR into operation causes a very lean fuel to air mixture by commanding the fuel injection to cut back as well as advance the ignition timing in addition to the exhaust being gated into the intake making the mix leaner yet. Exhaust gas does not burn the second time..



The results of this "normal" condition is a rise in coil voltage requirement because.the mix is in the 20 to 1 range and must have higher coil reserve voltage to fire the mix. A failure to fire is a missfire at that time.
This situation is not a "hard fault" so does not set a code because it is cancelled in memory as soon as the operating conditions change.
So, the next time this happens you get the same result over again;
it is a proven fact.
If you do not approch the fault in the proper way, have fun and enjoy the missfires.
Replace the offending coil or have them tested for output to find the one causing the hassle.
You may see this stored in another part of the program then again you may not.
It takes a good scanner not a reader to see anything and to "TRAP" the fault while running when it happens.

So I'm new to this site....I'm trying to repy to your thread...Hopefully this is where I write:
I have the problem described below...jerking at 40-50 MPH. My truck was in the law suit with the spark plug problems short time ago. Can this problem be fixed with the spark plugs or is it the coil pack. Spark plugs are not that old. Not even 2 years old. Do I take to dealer &. tell them it's the coil pack or should just check the spark plugs?
 
  #228  
Old 05-16-2018, 11:11 AM
lalat
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So I'm new to this site....I'm trying to repy to your thread...Hopefully this is where I write:
I have the problem described below...jerking at 40-50 MPH. My truck was in the law suit with the spark plug problems short time ago. Can this problem be fixed with the spark plugs or is it the coil pack. Spark plugs are not that old. Not even 2 years old. Do I take to dealer &. tell them it's the coil pack or should just check the spark plugs?
 
  #229  
Old 05-17-2018, 08:07 PM
Bluegrass 7
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Hello I thought you need a reply so here it is from a hospital room.
Usually faulty coil caused the misfires in OD at 'light' throttle. Usually no associated code sets to ID the cylinder.
To find the offending cylinder, look with a Scanner at mode 6, test 53. This is the misfire records for each cylinder.
The one with the high-count out of limits is the one. Others may show but if low, just ignor unless rechecks. keep showing the same as possible future failures.
Replace that coil for shorted turns issue.
Reason for misfires is the low coil output when the EGR is opened in OD causing very lean air-fuel ratios.
The lean mix needs. full coil voltage.
Good luck.
 
  #230  
Old 05-17-2018, 08:30 PM
rsylvstr
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Hope nothing major Bluegrass
 
  #231  
Old 06-14-2018, 07:43 PM
David40
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Please explain all this talk about multiple "coils". My 96 only has one ignition coil, and I thought only Jeep used individual coils for each cylinder?
 
  #232  
Old 06-14-2018, 07:56 PM
Bluegrass 7
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Dave, if you have a FORD 5L or a 5.7L push rod motor, yes you only have one coil.
The later over head cam 97 up FORD 5.4L all have 8 coils.
The FORD OHC 4.6L from about 2001 all have 8 coils.
The V10 OHC gas motor has 10 coils.
97, 98, 99-2000 OHC 4.6L have two coils for eight cylinders. 4 terminals each.
Hope that clears it all up for you.
Good luck.
 
  #233  
Old 06-14-2018, 08:51 PM
David40
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Wow, I had no idea they had changed that. So I guess the bad coil theory is not going to help me with what I call my hiccup issue? I get this hiccup when I try to accelerate, or even if the cruise control is on, if I come upon a hill where the control tries to apply more throttle it does the hiccup thing. It reminds me of back in the old days where the timing advance was controlled by a vacuum line to the distributor and you would have a vacuum leak. It would kind of hiccup and cough because you were trying to accelerate without advancing the timing. Only thing is, in my case it's intermittent. Sometimes it happens and most of the time it doesn't, but it's very irritating when it does happen. I'm not sure where to begin looking.
 
  #234  
Old 06-14-2018, 09:19 PM
Bluegrass 7
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It can still be a faulty coil.
The whole function gets a bit complex so try to follow along.
In OD at light throttle, the ignition timing advances, the fuel injection is cut back and the EGR opens, converter is in lockup..
This causes a VERY Lean air/fuel ratio by design..
When you add more throttle the A/F ratio gets leaner yet from more air!
All these actions are controlled by the computer program and designed to be transparent when there is no fault present.
It takes only one faulty coil to cause a misfire under these conditions.
As soon as the A/F ratio goes back richer from a down shift and EGR closing up, the misfire clears. This is why there is no code set because it's not a hard fault miss a normal code would be generated for. Reason is the program cancels the normal record but does peg count the mode 6, test 53 records memory location.. This location has no ability to set any code.
Using a Scanner to take a look will show it up.
.
That's not all!
This fault type can get so severe that it will stop the computer processing in rapid successions and cause a violent jerking.
This happens because the whole drive train is in engagement when the computer stops processing data (it cannot make any changes if not working) then resumes again.in rapid succession.
And you find your way behind the times from all this.
Aren't computer wonderful?
Good luck.
 
  #235  
Old 06-14-2018, 09:43 PM
David40
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My problem is compounded by the fact that 96 was a transition year from EEC-IV to OBD-1. My van was half way down the assembly line when they made the change so I have the OBD-1 Data Link under the steering column but the harness ends at the firewall. Took me a while to figure out my ignition was EEC-IV with the Data Link by the battery. When using most scanners I have to select 95 as the year or they won't work because the scanner manufacturers all expect a 96 to be OBD-1. In any case I am not getting any codes, and I am not sure the EEC-IV was sophisticated enough to actually vary the strength of the spark. Also, it is a fairly new coil which I changed because of a different issue I had that ended up being a dying stator in the distributor. So I doubt it's a coil problem.
 
  #236  
Old 06-19-2018, 09:21 AM
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I have similar issues with my 97 4.2 I've done just about everything twice and still seem to have this exact issue. It's a low spark on cylinder 4, I'm thinking the last step now it to replace the ECM? or the wiring?
 
  #237  
Old 06-19-2018, 12:40 PM
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I fail to see where people get these ideas from!
Why would you think the PCM or harness is the cause of (low) spark on one cylinder out of six that you have not conclusively proven?
The PCM closes a GROUND to each of 3 coils during the fire order.
Do you know the 4.2 ignition system is not the same as a 4.6 or 5.4?
The 4.2 v6 uses paired cylinder ignition. Two cylinders are paired times 3 pairs = 6.
Each pair actually sparks two cylinders at a time.
Faulty coil tower, faulty spark plug leads., faulty opposite plug , lead or coil tower..
Faulty cylinder mechanics.
Is the spark plug leads on in the correct order?
Plugged EGR ports in the intake manifold. This EGR is different than a mod V8 because the motor is still the old push rod design with converted EGR system.
 
  #238  
Old 11-17-2018, 09:28 AM
Give me a break auto
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The post are old have they got a permanent fix for this yet

Is there a permanent fix for this problem yet
 
  #239  
Old 11-17-2018, 10:33 PM
traildad
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If the problem is a bad coil or spark plugs or wires, then no. You can’t have a permanent fix for something that wears out. Kinda like a permanent fix for worn out tires or an empty gas tank.
 
  #240  
Old 11-18-2018, 06:16 AM
Give me a break auto
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Originally Posted by traildad View Post
If the problem is a bad coil or spark plugs or wires, then no. You canít have a permanent fix for something that wears out. Kinda like a permanent fix for worn out tires or an empty gas tank.
Right on , I do get that , thank you for your reply and thanks for being nice this is my first v3 engine and I'm still learning about them
 

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