99 f-150 5.4 170000 4x4

About a year ago I got P0401 Insufficient Exhaust Gas Reflow. It turned out to be the Dpfe. I changed it and then it threw P0402 Excessive Exhaust Gas Reflow. That went away though. A few days later a COP went out. I had to buy cheap parts due to the fact I had no job. I know!

Now P0401 came up again and I'm assuming its the dpfe. Already cleaned all the ports and its still under warranty. And a few days after that p0401 the truck started to kinda buck when I left off the gas around 45mph. After doing some research it appears that another COP isn't functioning properly.

I am just wondering if the dpfe not functioning right could case excess strain on cops or vica versa? Or do I just have bad luck and timing?

 

1. Direct relationship......NO.
2. Indirect by system design.....yes.
The DPFE is not the cause of a coil failure.
What you see happening is as follows, when the EGR is opened, (the DPFE is part of this system) the air/fuel goes lean by design from the exhaust gas introduced back into the intake and reduced fuel from the injectors as well as ignition advance.
When under this driving condition, the coils need to be able to fire the leaner mixture.
If one or more coils cannot because of low voltage output, you get the missfires.
A code won't be set for this because it's not a 'hard' fault.
So that's the indirect relationship.
The EGR operation can show up weak coils.
Too often circumstancial evidence leads to incorrect conclusions by attempts at association. You must know system operation to 'link' any actions correctly.
Good luck.

 

Your logic is sound. Makes perfect sense why that is happening. Makes me kinda feel stupid that I didn't figure that out after reading all the posts on cop's and bucking. I'll get her all fix up next weekend.

I know I should find the coil that is not working right but I'm a little short on cash right now. If I replace the dpfe to get the air/fuel mixture back to normal that coil should work properly for a few weeks right?

 

NO not gaurrenteed.
If the coil is heat sensitive, it may still missfire.
If the EGR system is inhibited from a fault, the motor will still run ok "if" there were no faulty coils.
The EGR system is 99% emissions only and affects the 'drivability' only a small amount by improving fuel mileage along with it's major purpose of lowering nitrogen oxides due to high combustion temperatures.
If you can get someone with a high end scanner to look at mode 6, TID missfire monitors, it may show cid 1 thru 8 missfire counts. Only the first 1-8 are for a v8.
Otherwise on a lesser scanner, look at the long term fuel trims to see which bank has shifted a large amount.
Working on these systems is no different than a on a computer but you need to realize the software/hardware relationships to get anywhere with an issue unless your lucky.
Good luck.

 

Well I replaced the dpfe and the bucking seems to have stopped but i havn't driven enough to see if it will through a code again. I was in the process of checking the resistance of the coils but I broke 1 in the process and it started raining so I couldn't move my truck into the garage. Below are some obd2 readings from the last time I had a p0401 and this time. Also there are the resistance readings of the cops. If I remember the cylinder numbers right. 1-4 are on the passenger side with 1 in front and 4 in back. 4-8 are in the same order on the driver side. If I'm understanding everything correctly then there was a big difference in Bank 1 LTFT and that is the passenger side bank. So I'm thinking that it was the cheap cops causing the bucking. Right?

Old Data
Calculated LOAD Value 63.53 %
Engine Coolant Temp 197.60 °F
Short Term Fuel Trim - Bank 1 -1.56 %
Long Term Fuel Trim - Bank 1 1.56 %
Short Term Fuel Trim - Bank 2 -1.56 %
Long Term Fuel Trim - Bank 2 3.91 %

Recent Data
Calculated LOAD Value 70.98 %
Engine Coolant Temp 174 °F
Short Term Fuel Trim - Bank 1 -1.56 %
Long Term Fuel Trim - Bank 1 4.69 %
Short Term Fuel Trim - Bank 2 -2.34 %
Long Term Fuel Trim - Bank 2 4.69 %

Cyl. 1 - 5.81 - cheap cop
Cyl. 2 - 8.17 - motorcraft - broke while removing
Cyl. 3 - 4.68 - cheap cop
Cyl. 4 - 8.95 - motorcraft
Cyl. 5 - 8.76 - motorcraft
Cyl. 6 - 8.65 - motorcraft
Cyl. 7 - ? - I hate the rain
Cyl. 8 - ? - I hate the rain

 

Well went and bought a new cop to replace the one I broke. Its made in America and has a lifetime warranty which isn't bad for $49. I checked its resistance and it was around 5.5ohms. All of the other non-motorcraft cops have similar resistance. Do the motor craft cops have a higher resistance because that is the way they're manufactured or are they getting old? Any other thoughts or info appreciated.

 

Coils:
1. Your meter accuracy is always in question for indication of absolute values.
2. Your ability to hold a good connection to the coil while measuring such low resistances is difficult as it can change the reading you get. The test leads are even a sensitive part of the measuring circuit as well as their meter socket connections.
3. The accuracy with which the coils are wound for number of turns, is a matter of quality control/ who makes them etc..
4. Shorted turns will lower the coil resistance. It shunts down the magnetic field around the core causing lowered voltage and higher current to flow, further affecting the coil over time and heat cycling.. You cannot measure for one shorted turn.
5. A smaller number of turns in the primary will tend to increase the output voltage and may shorten life, unless the coil was redesigned with different wire to get higher outputs along with reasonable life under the operating conditions..
6. And the list goes on.
Coils are thought of as simple devices of wire but their is much more to their design in this more critical apllacation.
Take your pick of any combination since you can never know what ones were at fault.
.
Coils are a service item no matter how you look at it.
The "ISSUE" is, people can't associate this with the "cost" of 8 coils at a time or even one coil. It's all in the 'head' as they say.
No different than having to buy 1,2 or 4 tires which cost more then coils from an OEM standpoint, that few complain about when they have to be replaced. They wear out too and you get even less life out of tires than coils!
.
Remember the coils have a hard existance/life where they are located on the motor.
There is tremendous heat transferred up from the 'plug well' as well as the ambient heat from the radiator and exhaust manifolds along with heat cycling. The greatest damage point is just after motor shut-down when there is no cooling at all, and everyhting is hot and temps rise for a few minutes before starting to subside.
As an example; a radiator hose that has gone hard from age is most likely to blow at this time because it cannot strech to accomadate the increased system pressure just after motor shut-down.
My opinion is the coils could be redesigned better and a way to get some cooling on them with some kind of forced cooling manifold around them.
But then the normal reasonable life they have now by design, makes them just a replacment part like anything else.
This horse is beat to death.