V-10 Excursion missing; no code or pending code

The DPFE thing is fairly common. Mine did this last month. Gave it a shot of sea foam and it cleared up. I have replaced it twice so far.
If you have a decent OBD II scanner, it should show if you have a miss. It would show up as low rpm or hi rpm miss bank 0 or bank 1. It won't tell you which cylinder is affected. (The ECU on these trucks are not very robust in the control department) I just replaced the boots after talking to a mechanic that works on local PD cars. Then replaced 1 coil after disconnecting them one at a time until I found one that didn't affect the idle. OBD ran clean after that.
MikeH

That is exactly what I have. I would call it a shudder at 1500 RPM and below when ascending a hill. It isn't bad enough yet for me to do all that. It occurs infrequently, at least as of now.

I expect it will get worse and finally set a code! I need to get out my receipts and figure out what COP's haven't been replaced since my replacement of all 10 with Motorcraft units about 3 years ago.

jspringator wrote:
My oldest COP is 3 years old. I replaced all the plugs at the same time, and replaced each plug when I replaced the coil. And I have replaced plenty since then. When they fail, they always set a pending code. I think it needs a heavy dose of seafoam and an italian tune up. Did a few full throttle starts with seafoam and it is doing better. It may be carboned up due to my grandfatherly like driving. I haven't towed since June.

BTW, here is an interesting post on FTE forum about ways to keep water out of the spark plug wells.

http://www.ford-trucks.com/forums/1185557-getting-water-on-your-plugs-heres-the-fix.html


Another technique is to liberally grease the tips of the boots to slow the water wicking process that destroys these coils. One guy added an o ring on the COP.

Bad COPs do not ALWAYS set codes.

I ran into that on my 5.4, it would shutter around 1500 RPM under a light load or acceleration. Did not set the CEL nor was there any pending codes other than a few random misfires found at the dealership.

They ended up having to take a new COP and sub it into each position until the bad COP was found.

The bad COP had a very small crack around the grounding screw... Was nearly impossible to see the crack.

jspringator wrote:
What is a DEPF and how do I check it?

It's basically the EGR pressure sensor. Usually it will set EGR codes when it starts failing. I don't believe its a common problem.


With a problem you are describing, it may take a long time to diagnose without the proper equipment. The most useful test at this point would be a "cylinder contribution" test. This requires the Ford IDS shop computer, or something equivalent like Snap-On Modus or AutoIngenuity. This will show which cylinder(s) are weak. At that point, individual can be tested. Injectors are easy because they can be turned off individually. All dealers and some independent shops also have a COP tester, that way you aren't just replacing good parts. That said.... if you have aftermarket coils.... I'd be awfully suspicious of those.

What is a DEPF and how do I check it?

If you are OBDII then you have a DPEF sensor and they go bad and do exactly what you are describing. I have also had a lot of mod motors and the cop/spark plug miss tends to appear around 2000-3000 rpm at light load. (Mostly in third gear)

The lighter miss off idle has always indicated a DEPF failure in my experience with three different mod motors.

If it's the DEPF it will throw a CEL before long. Mine also proceeded a 100% catalytic converter failure on a 5.4. (that was FUN)

Good luck.

Jeremiah

The plug boots on the coil packs go bad they can be changed. They will not give a code when bad. Have been driving only Fords for over 30 years. Changed many plug boots they do not cost very much, and are most of time the only problem not the coil packs or the plugs.

Check injector connections. That sounds promising. I've had a BUNCH or coils go in and out of this thing.

WHat did you put in as replacements?

I only ask because most of the aftermarket brand COPs have a much shorter life than the Motorcrafts. About the closest store-brand I've used is NAPA Echlin but those cost nearly double the Motorcrafts!

Also, check all you fuel injector connectors. Its VERY easy to break off the retaining tab when changing the adjacent coil. I've broken all of mine, so now my injector connectors are all zip-tied to the injector. One backed off once on a drive from Whistler, Never threw a code but made the idle less smooth, and the emissions were were pretty smelly. Ran fine while driving though.

My oldest COP is 3 years old. I replaced all the plugs at the same time, and replaced each plug when I replaced the coil. And I have replaced plenty since then. When they fail, they always set a pending code. I think it needs a heavy dose of seafoam and an italian tune up. Did a few full throttle starts with seafoam and it is doing better. It may be carboned up due to my grandfatherly like driving. I haven't towed since June.

BTW, here is an interesting post on FTE forum about ways to keep water out of the spark plug wells.

http://www.ford-trucks.com/forums/1185557-getting-water-on-your-plugs-heres-the-fix.html


Another technique is to liberally grease the tips of the boots to slow the water wicking process that destroys these coils. One guy added an o ring on the COP.