2017 Expedition - Jerky acceleration, misfires (P304, P300, P305)

[Cody Hall]

Hello Expedition Owners. I have a 2017 Ford Expedition Limited (2nd gen Ecoboost 3.5L V6) with 120K miles on it (purchased at 72K miles). I am hoping for some help and direction with the current issues I am experiencing. When I punch the gas to accelerate rapidly, often times the truck will accelerate very choppy and you can fill the truck surging as it accelerates, with the check engine light flashing at me. This only happens when I get on it, say I am passing someone. Also, sometimes the truck does not want to accelerate or down shift, sometimes for up to 5 seconds, which seems to happen after I have accelerated somewhat rapidly (although very choppy like as mentioned).

After some time, the CEL was on permanently. I pulled the codes with Forscan, and got P304 (misfire on cylinder 4). So I replaced the spark plugs since they had close to 50k on them, cleared the codes, but that did not resolve the issue. Next, I swapped the ignition coils between cylinder 4 and 5 to see if I had a bad coil (they have never been replaced). Now I am getting a P300 and P304 (permanent codes with CEL on), BUT also have a P305 (cylinder 5 misfire) that is still pending in the PCM! What would be the next thing to do, replace all the ignition coils? I would think that if the coil was bad on cylinder 4 that it would have transferred to cylinder 5 when I swapped them, but I am still getting cylinder 4 misfires. Should I go ahead and replace all the coils given that they are still original coils with 120K on them? Or do you think this could be something else? Here are some additional items for consideration:

Bad fuel injectors (probably never replaced). Could this be causing the issue?
Exhaust manifold leak (passenger side). We did replace the driver side due to the famous broken stud issue, now the passenger side has a small leak you can hear when accelerating quickly. Could this be causing the random misfires?

I hate to just replace everything in an attempt to fix this issue, as that can get expensive. What would the logical next step be to diagnose this issue? Any help or guidance is greatly appreciated.

 

[S20Workstation4]

No, you should not replace any of the coils. If any coils go bad, the computer will set its own "bad coil" codes. Coils do not have to be changed at a certain interval because they are considered a non-maintenance part. A coil may go out around 200k miles, 120k is too early.

Fuel Injectors are most likely not the problem, I have 224k on my Expedition and still have the original injectors. Gas Mileage hasn't changed one bit since new.

What does the instrument cluster say for gas mileage? If it is low, you might have carbon build-up on the intake valves (inevitable for DI engines). Carbon build-up on the intake valves is also coupled with misfires on a cold start. If you do cold-start misfires, this most likely is your problem.

Right now, i would try to run a bottle of fuel system cleaner (Techron, Cataclean, etc), and see what the results are after you run it through the system. Strictly follow the directions on the bottle.

Hope this helps,
- Joseph

 

[Cody Hall]

Thanks Joseph. Good to know that the injectors are probably not the issue here.
Gas mileage has been fairly consistent around 13-14mpg. I already ran some fuel injector cleaner as a recommendation by the parts store where I bought the plugs (O'Reilly brand fuel injector cleaner). I didn't notice any difference afterwards, in fact I would say it has got worse over the past 30 days since the cleaner. This also occurs when the engine is at full operating temperature, even after driving around for an hour, but I would say maybe a little worse when cold.

I cleared the codes with my scanner a couple days back, and waited for the light to come back on. Tonight when I checked the codes again, I found quite a few more codes that I have not seen before (see attached screenshot):
U0423 - invalid data from Instrument control panel
P0304 - cylinder 4 misfire
U2101 - control module config incompatible
U0100- lost comms with ECM/PCM
U0121 - lost comms with anti lock brakes
U0131 - lost comms with power steering
U0151 - lost comms with restraints control
U0159 - lost comms with parking assist

All these additional codes regarding lost communications make me think I have a bad PCM or there is a bad connection to it. Do you think that all of this is related, causing engine misfires, possibly pointing to a bad PCM/ECM?

 

[Cody Hall]

Here are the codes from Forscan

 

[S20Workstation4]

I'm almost sure that you cause is not a bad PCM or a bad connection to the PCM, usually those codes will come up when the battery suddenly died. I can also happen if your battery voltage is low and when you start the car, the starter takes enough power to temporarily shut down a module.

A PCM only lasting for 6 years/120k miles is extremely rare, it could only happen if it was somehow damaged/car was driven through rough conditions.

Occasionally, my expedition will say "lost communication" with a bunch of modules, but I notice no symptoms, and only even see when I plug in the scanner. Sometimes those codes come up when you previously clear the codes, because it will temporarily shut down and restart the module when you clear the codes. It is nothing to worry about.

13-14 mpg is pretty low for a 2017 Ecoboost, do you do a lot of city driving? Carbon Build-up on intake valves can be shown by a low mpg number.

Carbon build-up seems like it could very well be the issue here. To check for it, you could take of the intake manifold and look down at the valves, and see how well built-up the carbon is. Make sure that valve is closed fully, if you try to scrap the carbon off with a small screwdriver or something. When you take off the intake manifold, make sure that you blow around it with compressed air, so that no foreign debris fall down into the intake holes. A mechanic shop could also do this, if you didn't want to do it. On average, the ecoboost engines start getting noticeable carbon build-up approximately at 100k miles, so if it is affecting your Expedition, it could very well be.

- Joseph.

 

[JasonH]

Get your battery tested and check the plug wells for contamination, such as oil seeping in. I've gotten similar intermittent U0 codes when my battery was running low. One of my plug wells had some oil in it. This can cause fouling if the oil gets into the plug. Also check the plug gap on the plug that misfired. You can also try reducing the gap on cylinder five to no more than .030.

 

[Cody Hall]

Thanks Joseph. We do a combined highway and city driving, so I agree MPG is a little low. That makes me feel better knowing that those communication codes may be due to clearing the codes, as they only showed up when I was actively using Forscan.

Anyways, would you recommend that I use a product like CRC GDI Intake Vale and Turbo Cleaner and run it through the intake to clean the valves? Or do you think I need to remove the intake manifold and properly clean all carbon buildup off the valves directly with a screwdriver, brush, and some cleaning agent? I believe I could accomplish this following some online videos I watched this morning.

 

[Cody Hall]

Thanks Jason. I just replaced the spark plugs and did not notice any oil seeping in the plug wells, however, can't say that I was watching for oil specifically. I didn't notice any on the plugs that were removed, and they actually were not too bad as they only had about 30k on them.

I will check the battery to ensure that it is working well. I did replace it last year when the cold hit, so it's only 1 year old Costco battery (Interstate). I did notice that is has some corrosion on the positive battery terminal so I will make sure that gets cleaned.

 

[S20Workstation4]

Thanks Joseph. We do a combined highway and city driving, so I agree MPG is a little low. That makes me feel better knowing that those communication codes may be due to clearing the codes, as they only showed up when I was actively using Forscan.

Anyways, would you recommend that I use a product like CRC GDI Intake Vale and Turbo Cleaner and run it through the intake to clean the valves? Or do you think I need to remove the intake manifold and properly clean all carbon buildup off the valves directly with a screwdriver, brush, and some cleaning agent? I believe I could accomplish this following some online videos I watched this morning.

You can try that cleaning product, I was actually completely unaware you could use a cleaning product for the valves. It wouldn't hurt to try, hopefully it fixes the problem. If it doesn't do any help, I would try to remove the intake and inspect the valves for carbon build-up.

 

[Cody Hall]

I fixed the vehicle this weekend so wanted to follow up for those interested.

I decided to manually clean the carbon off the intake valves (I read that using a product like CRC cleaner through the intake is hard on the turbos). So I took the intake manifold off, cleaned all the valves manually, and reassembled with new gaskets. It took me most the day to do this (I am more meticulous than fast), but mostly because its very hard to access each valve and clean them well, especially cylinders 3 and 6 towards the rear which are almost impossible to see the carbon buildup due to the angle. I used a screwdriver to chip away at the carbon, an air wand to blow it out, soaked each valve with CRC intake valve cleaner, and used some different sized wire brushes attached to a drill, and I was able to get them fairly clean. It did take a lot of patience and back breaking work to climb into the engine bay to access each valve. There was mushroom headed carbon buildup on each valve, some worse than others. I will attach some before and after pictures for anyone interested in how much carbon buildup this 2017 ecoboost had after 120k miles.

So after reassembling, I took the vehicle for a test drive, hoping the expedition would accelerate properly again. However, the issue was still occurring! The carbon cleaning did not help with this jerky acceleration and random misfiring issue. However, I am glad I did it since it most likely was impacting performance, or soon would be.

l had also bought a new a PCV valve as I had never replaced it and figured it was time. After determining the carbon buildup was not the root cause, I went back home to replace the PCV valve. To my pleasant surprise, this completely resolved the issue! I wouldn't have thought this could the cause of my misfires, but now it makes sense after reading up more on its function. During acceleration, it seems the pressure in the crank case was too high and couldn't vent properly, causing random misfires (at least that is how I understand it). I would love to hear from others if they have experienced this issue or heard of it. At least I wanted to share my findings after working on the vehicle all day. In the end, a $10 PCV was the solution to my misfires and jerky acceleration!

Update: Flase alarm, just took the Expedition out this evening and it happened again. Dang! Thought for sure it was fixed, but apparently not, maybe this is more of an issue when it's cold. Back to square one.