Hellllllo all, yet another car-repair guidance post…

I have a 2016 Flex Limited w/Ecoboost… about 97,000 miles.

Yesterday on the way home from work while entering the freeway it started misfiring significantly… enough that the flashing CEL kicked in. I immediately worked my way to right to find a safe place to stop and as I exited the freeway the misfire seemed to go away and the CEL turned off.

After pondering this for a minute I decided it seemed whatever happened was likely related to the hard acceleration, but also wondered if the heat (was 112) may have been a contributing factor.

I continued on my drive home, but on surface streets. As I got closer to home I decided to do an experiment and accelerated hard again. Sure enough the misfire came back.

This morning I decided to try and recreate one more time to see if outside temp was part of the problem. I was able to reproduce the problem at 3:15 this morning with a cool engine and 75 degree air temp, so heat wasn’t a factor.

My scanner indicates the misfire was in cylinder 6 every time.

Here is my intention: please advise if this isn’t a good plan:

1: Swap the coil from cylinder 6 to cylinder 2.
2: Swap the plug from cylinder 6 to cylinder 4.
3: test drive to attempt and recreate a misfire and use the scanner to see where it is. Replace coil if appropriate.

Additionally, the manual calls for plug replacement at 100,000 miles. Given that, I plan on replacing all the plugs once I figure out the direct cause.

Also, is there any reason to use Motorcraft SP580 vs SP534? The 534 was original part, but it has been “supplanted” by SP580. I happen to have access to some NIB 534 from a family member who had a stock pile. Should I just use the 534’s?

Personally, I’d do the coil swap first to see if the code does come back, but switches cylinders. If it does, change that coil pack for sure.

I’d probably also change the plugs at the same time to be safe, even if you do verify a faulty coil pack. As for the part number, well, you got to almost 100k with what you have access to. Worst case is you’ll have to swap the plugs to the newer part number sooner than expected.

Just my opinion.

If you're going to DIY, plugs are pretty easy, but requires pulling the upper intake plenum, assuming it's the same as the N/A 3.5 V6.
Not tough, just an extra step.
Add in an intake gasket, just in case.

quote:

1: Swap the coil from cylinder 6 to cylinder 2.
2: Swap the plug from cylinder 6 to cylinder 4.
3: test drive to attempt and recreate a misfire and use the scanner to see where it is. Replace coil if appropriate.

That's what I would do. Also inspect the plug for carbon tracking or cracks. And be thankful the miss is on the accessible (not under the intake manifold) side.

quote:

Originally posted by P250UA5:
If you're going to DIY, plugs are pretty easy, but requires pulling the upper intake plenum, assuming it's the same as the N/A 3.5 V6.
Not tough, just an extra step.
Add in an intake gasket, just in case.

It seems it is different than the non-turbo version. YouTube shows it is done by moving some wires around but not removing anything of substance.

quote:

Originally posted by thumperfbc:

quote:

Originally posted by P250UA5:
If you're going to DIY, plugs are pretty easy, but requires pulling the upper intake plenum, assuming it's the same as the N/A 3.5 V6.
Not tough, just an extra step.
Add in an intake gasket, just in case.

It seems it is different than the non-turbo version. YouTube shows it is done by moving some wires around but not removing anything of substance.

Well that's fortunate.
I'll likely be doing plugs on my sister's N/A 3.5 V6 Edge this weekend, looks 99% the same as our old Flex.

Hope it's an easy fix for you on yours.

Had the same thing happen on my 2015 F150 Ecoboost. It ended up being a coil failure due to a leaking valve cover gasket that fried the coil

Since the plugs are due to be replaced I would just replace them and all the coils as well. I had a 2013 F150 with about 89K miles when it threw the code for a cylinder misfire. The check engine light came on and you could feel the engine missing under acceleration. Replaced the plugs and coils and all was well.

I take the maintenance schedule and cut in half.
I replaced my 3.5L Ecoboost plugs at 50k and they needed it!
It’s a easy job.
I used Autolite Platinums. Autolite makes MotorCraft plugs and you’ll save about 1/2 going that way. All Iridium does is give a longer service life. I am not a fan of having spark plugs in a block for that long.
50k is the longest I’ll go so I have no need for the Iridium. I always use Autolite plugs in my American cars and Denso or NGK in my foreign vehicles.

Make sure you are changing your boots as well. I had two that were dried and cracked at 50k.

https://www.rockauto.com/en/ca...tion+coil+boot,10150

I also suggest running an oil separator/catch can on these motors.

Also be very careful with the plastic of the coils they get dry and brittle. I broke the edge off one removing it. Thankfully it was no big deal as it was just the edge.

I've not had much time between 16 hours shifts to do a lot with this, but I did take a couple of minutes on a break while at work to switch the coils on 4 & 6. When I head home tonight I'll try and induce the misfire and see what cylinder it is occurring in.

I didn't want to swap plugs around in the parking lot at work, so tonight's test will only be diagnosing the coil. We'll see what happens.

quote:

Originally posted by Black92LX:
I take the maintenance schedule and cut in half.
I replaced my 3.5L Ecoboost plugs at 50k and they needed it!
It’s a easy job.
I used Autolite Platinums. Autolite makes MotorCraft plugs and you’ll save about 1/2 going that way. All Iridium does is give a longer service life. I am not a fan of having spark plugs in a block for that long.
50k is the longest I’ll go so I have no need for the Iridium. I always use Autolite plugs in my American cars and Denso or NGK in my foreign vehicles.

Make sure you are changing your boots as well. I had two that were dried and cracked at 50k.

https://www.rockauto.com/en/ca...tion+coil+boot,10150

I also suggest running an oil separator/catch can on these motors.

Also be very careful with the plastic of the coils they get dry and brittle. I broke the edge off one removing it. Thankfully it was no big deal as it was just the edge.

I didn't think about the boots... I'll have to grab a set to use when I do all the plugs. I had read somewhere that NGK is the manufacturer for Motorcraft... maybe it depends on the specific application?

Any more info on a separator/catch can? I don't really know what it is... I don't know much about turbos.

Following for catch can info.
I didn't have one on my 2.7TT F150 but only had it to about 36k miles.

The MiniBus (wife's name for the Expedition) is at 35k.

Every Ford I have come across including my 2015 Expedition that had the 3.5L Ecoboost has been made by AutoLite. Though it is possible they have used others.
Every spark plug I have bought and used in American vehicles has been an Autolite and have always treated me well. NGK and Denso are great plugs too just tend to be a bit more expensive and not a noticeable amount of performance gain for the added few bucks.

As for the oil separator they come in handy for many applications that suffer from excessive oil blow by through the PCV system. In other words a small to moderate amount of oil gets past the PCV and goes into the intake mucking up you intake, throttle body, and onto your plugs.
Forced induction motors are prone to see more oil in the system than others.
The oil separator attachs to the PCV system and collects that oil in a catch can. Generally just emptying it when you change your oil is sufficient.
JLT is probably the king for simple plug and play applications. (Guess I am a little behind and JLT is now known as J&L).
https://www.jlosc.com/JL-3-0-o...oost-passenger-side/

Thanks for the link. Is the 3oz usually sufficient, or worth the little extra for the 6oz can?

quote:

Originally posted by P250UA5:
Thanks for the link. Is the 3oz usually sufficient, or worth the little extra for the 6oz can?

Presuming your truck is going to stay pretty much stock and you do 5k mile or less oil changes you should be fine with the 3 oz.
It takes less than 2 minutes to unscrew the can, pour out the contents out, and reattach the can.

Thanks for the info, Black.

Do we like anyone other than Motorcraft for coils in the event one/they get changed out?

Motorcraft coils are made by Denso. NGK coils are good also.

As for plugs get the NGK Ruthenium spark plugs. They are the way to go if they make them for your application. NGK makes many if not all the Motorcraft plugs these days.

So, as I said earlier I’ve moved the coil from 6 to 4, and from 4 to 6. I shot some new dielectric grease into each boot.

I tried to trigger the misfire again on my way home last night but it simply would not happen… it just ran well. Perhaps even felt like it had a little more power than before?

So………… I’m not sure what this means. My best guess is the coil is a little weak and that by reseating it with some fresh diaelectric it is better able to do it’s job? The plugs are still going to be changed as it is due, I’m just not sure if I should do anything else? Preemptively change out that one coil? Buy a spare and keep it in the car?

This message has been edited. Last edited by: thumperfbc,

I have a 2012 Ecoboost with over 265,000 miles. When I get a misfire,
I run it hard to make it generate a code that indicates which cylinder is mis-firing. Then, I remove the plug, clean it with emory cloth, apply dielectric grease to the boot, and re-install. The problem goes away.

I bought OEM plugs and coils for my F150 from Village Ford Online Parts. They sell most parts at a discount and I've had good luck with them getting stuff to me in a reasonable amount of time.

Ford White Bear Lake was another OE parts source that was recommended back when I had my F150.