Still chasing my Cylinder Contribution codes, engine runs fine when cold, develops a misfire when warm.
What does the PCM use to determine one of the cylinders is not contributing?
I am assuming that the PCM uses the following inputs, please correct me where I am wrong

• Crankshaft speed sensor - because the code indicates the PCM sees the crankshaft decelerate at a misbehaving cylinder
• Camshaft position sensor - would tell the PCM which cylinder is currently in a combustion position
• ?

I'm entertaining the idea that perhaps the injectors are good, the FICM wireharness is good, and the FICM is good. Could an intermittent sensor issue *cause* an actual rough idle/run condition, or would it just throw bad codes?

The guys at Accurate Diesel assure me there would be additional codes if the FICM harness were depriving injectors of the electric signal to actuate, especially because the problem happens every rotation after warmed up. They keep pointing me back to their injectors.
The IPV screen was clean of metal, and other debris, was not damaged. Replaced the screen anyway, just because I was there. Code moved from Cyl 3 (passenger side) o Cyl 4 (the side I'd been futzing with doing the IPV screen.
Replaced the IPR connector (passengerside) and inspected driverside FICM harness to ensure it wasn't misrouted, and poked at the cyl 4 connector. Code moved back to Cyl 3

This engine is a machine, an appliance, I know it can be repaired. Your thoughts, opinions, and educated guesses are welcome, I have the time, tools (and resources to buy more tools), and mechanical ability. Years of diesel experience I do not have, yet.

Thanks

 

After playing with the truck some, I realized the PCM does not monitor some of the sensors immediately at cold start-up. Unplugging an air intake sensor prior to cold start-up results in a delay to store the code associated with it. If it is not the same amount of time as it takes for my Cyl contribution code to pop (along with the deteriorating idle), it is pretty darn close, and appears to be temperature related as well...
Using the above guesses as to what the PCM uses to determine if a cylinder is misbehaving, and assuming those same sensors are used in a feedback loop to instruct the FICM to actuate the correct injectors, I've got a theory to test.
Can a "nearly failed" cam or crank position sensor send a slightly wonky signal to the PCM and influence the PCM to alter the timing of one or more cylinders? Put another way, if one of those sensors were to tell the PCM that a well running engine is off a little bit at one cylinder, would the PCM tell the FICM to adjust it's timing, or something similar with the fuel or oil delivery systems?
When does the PCM begin adjusting the ( I forget the term used right now) fueling system to even out the cylinder contribution, in an effort to correct for the slight differences between cylinders?

 

Compensation... that's the word I was looking for... has there been any experiences where a marginal sensor input caused the compensation performed by the PCM to smooth things out led the engine into a rough idle?

Does the PCM begin this compensation immediately from startup (open loop), or does it start up in a closed loop mode where it is immediately trying to level things out?

 

So, I'm guessing I'm entering uncharted territory in this troubleshooting journey, which is okay. I've ordered a Motorcraft Cam Position sensor and a Delphi Crank position sensor (couldn't find a motorcraft, and I work for APTIV, which is a spin-off of Delphi, and I still support Delphi manufacturing sites worldwide), which will arrive mid-next week.
I've recognized that when I have parts in my hand to install, I am impulsive and just install them and put everything back together to see what happens. To combat this tendency, I'm bringing the Excursion into the shop and preparing it for the sensors and injector install next week. Clearing all of the stuff off the topside and probably frontside of the engine will allow me to do the deep cleaning that I know it needs and allow me to give a real seriously close look at the different harnesses and connectors for weirdness. I imagine it's going to be a couple cans of brake kleen, simple green, and purple power, along with a 'bag of rags'.

 

I think the best way to go about correcting a problem after troubleshooting is to replace one component at a time. Then seeing if anything improved. Often you read of a person that swaps or replaces numerous components in one sitting and then a new problem shows up and it is even harder to work it through.

 

Agreed, that's why it's such a slow process
It is tempting to throw all of the parts at it at once, but let's be honest, anyone can change parts.

 

OP -- OBD operation atch'd and please pay attention to the Misfire Algorithm Processing. Good Luck and please never throw parts at the problem -- my experience with aftermarket parts shows almost 10% marginal or bad OUT OF THE BOX (especially the crap from China) -- don't need to add new problems to old. Isolate to the source of your problem.

 

Thanks for that document. It confirms how the system works and makes sense to me. My work in fuel injection (gas) in a previous job helps a lot with terminology and logic.
I'm definitely moving towards believing one of the wire harnesses is damaged. I need to replace the FICM harness anyway because of the broken locking tabs at the FICM, but I'm suspecting the cam position sensor wiring (actually the shielding) may be damaged and there is noise in the signal.
fun fact for this specific problem, the code seems to jump between cyl 3 and cyl 4, but the AE power balance chart (ver 12) doesn't change, and I would suspect cyl 5 from looking at that. The current code is 0269

 

If you can'r laugh at yourself, who can you laugh at?
Reviewing my notes I realized that I'm chasing a ghost. I've been whining about a misfire that's moving between cyl 3 and cyl 4. AutoEnginuity is showing a P0269, Cylinder 3 Contribution/Balance. TorquePro also shows a P0269, and say's it's a Cyl 4 contribution/balance failure....

So, I'll still clean the valley, I'll figure out which injector is actually the P0269, and with any luck, the old girl will feel a little better....

 

Latest update... I'm getting a lot faster at opening up the valvecover and swapping in an injector.
Replaced the #3 injector today with a Ford reman. Remember, it wasn't long ago that I replaced #5, and just about a week prior to that, I replaced all eight...

The P0269 cylinder 3 contribution/balance code didn't come back. Woot.

However, similar symptoms returned after warm-up (130-ish F oil temp), P0272 Cylinder 4 contribution/balance...

Another call to Accurate Diesel, four Ford remans are on their way for the even numbered bank. It may be a good way to spend an evening, but every time you open up an engine, you're asking for another problem. Might as well do them all again at the same time.

While I was playing with it this morning, I pulled the IAT1 pins and found the intermittent break in the wire. I soldered the wire to the pin, retaped the harness, and had success.

 

Are you happy with the injectors from Accurate Diesel? I am gonna order 4 of them, for the odd side.. I also have contribution/balance codes through Forscan lite, torque pro doesn't show any codes for cylinders 1 & 3. Just want to know if your happy with them? I was looking at option #1 injectors.

 

I'm happy with the people that work at Accurate Diesel. At this moment, looking at my fourth time under the oil rails in about as many weeks, not overly impressed with the $172 versions. All 8 of those are being replaced with the next level up, the ones with new spools, and then hopefully I'll be happy with them. I'm possibly blaming the injectors for something that isn't their fault, I do have a fresh cam sensor ready to go, as I see that's an outside possibility, and I just ordered the parts to install an electric fuel pressure gauge. That was a tough one, at $200+ for an autometer, but I couldn't bring myself to risk the glowlight stuff. It was really tempting to stick a mechanical in there, since the risk of death by gasoline fire is significantly reduced with a diesel truck, but I also don't need 60psi (or whatever) of diesel blowing around the interior either.

But to answer your question very directly, if I ever need to replace them again (when I need to replace them again), they will be Motorcraft from White Bear Lake or Tascaparts.com. I'm getting way too comfortable under the valvecovers....

 

Good to hear that Accurate Diesel is taking care of you.

Totally agree about Ford Remans, and with buying them an ANWBL!

 

For kicks today, I tried to install a fresh cam position sensor. Getting the original out wasn't too bad, fortunately I have skinny arms and could reach it from the top after removing the bolt from below. I really feel for the guy who had a rusty bolt there and rounded it off, that would add a ton of work.
Removed the old one and inspected it. Orings both looked good, the oil on it was a little darker than I'd like. The end of the sensor did have some small grit on it, didn't appear to be metallic, or even hard, but there has been something going on in there over the past 200K. Wiped it clean and compared it to the new Motorcraft, same part, all seemed good. While inspecting the new part, I found two things. It had been previously installed, the oring closer to the tip had an install mark/stain on it, and the metal part was slightly bent off axis from the plastic part. I really don't like people who return damaged or old parts as new, I once bought 4 gallons of used Rotella synthetic and that was an unfortunate discovery at home alone with my car blocked in by the truck with no oil in it... But I digress....

I inspected and found no obvious damage to the wire harness, no heat damage to the sheathing and the connector was clean and dry. I re-cleaned the original sensor and re-installed it, without any further troubles and restarted the truck to confirm the contribution code returns when warmed up, at the same cylinder, and it does. While not 100% sure the camshaft sensor or wiring is not adding to the problem, I'm pretty sure it's not. I also learned a little bit more about this engine, so it wasn't time wasted.

The replacement replacement injectors for cyl 2,4,6,& 8 arrive on Thursday, so I'll use my Friday Furlough time to swap those in.

For anyone keeping track of the new tools count... because new tools make everything better

• Proper socket sizes for Fuel and Oil filters
• IPR Socket
• Harbor Freight Earthquake 12v ratchet (way easier to use than my air powered ratchets, I know, "welcome to this century old man"
• 12mm Hex Bit socket (part of a set of 10mm-19mm) for the standpipes and dummy plugs
• 8mm, 10mm, and 12mm shallow well swivel sockets (haven't found the deep or medium versions yet)
• and of course, a couple 10mm sockets to replace the one that evaporated into the miata somewhere while repairing the crash damage from Road Atlanta

 

Today is like Christmas, four fresh injectors have arrived for the even side of the engine. While waiting for the delivery, I finally took the time to repair the overhead console circuit board, so I'll know what direction I'm pointed and have a good idea of what my fuel mileage might be...
New question, since I'm assuming the cylinder contribution issue will be solved today (fingers crossed)

I've got the fuel pressure gauge ready for install. While I'm fishing wires through the firewall and stuff, what other monitors *should* I be adding that aren't already visible in TorquePro? Over the past month, I've become attached to this engine and have learned to enjoy puttering around with it...