The New Used F250 Battles

[rockmeupto125]

Okay, I picked up that truck I yammered about in the Pub.  It's a 2015 Ford F250 Superduty 6.2 gas, 4WD Supercab equipped with factory duel fuel CNG.

 

I get the impression of an abused mule.  We're not really communicating.

 

Not too long after I got it, I noticed some jerkiness that led to a P0301 code for a misfire on cylinder 1.   I drove it for a bit, thinking some fresh gas might just straighten it out. It didn't, and the miss got worse.  I bought a generic coil to replace the original.  A quick review might be important here.  The 6.2 in this year had a dual plug head.  A coil over plug has an output for a traditional type of plug wire to transfer to the second spark plug.  So I changed the coil, and things seemed to be better but not perfect.

 

Shortly before NotRacer, I took the truck out for a long shakedown run, and low and behold, under heavy load, I again was able to generate P0301 several times, and once a P0308, although once is an anomaly.  My "once bitten twice shy" side rented a truck from Enterprise to haul the trailer to Florida.  Not doing that crap again stuck in Nowhere In The Mountains (Actually it was on Tater Hollow near Hillesville, VA).

 

Now I'm messing with the Ford again.  I swapped the spark plug wires from cylinder 1 and cylinder 2.  I had changed the coil and still got the code.  So now I swap the wire.  If it's the wire, it should give me a P0302.  If the new coil is not good, I'll still get P0301.  And I still get P0301.  Then I put the number 2 coil on the number 1 cylinder.  And I still get P0301.  Sigh.

 

I'm trying to research what parameters trigger the misfire code, and all I can find is a deviation of greater than 2% engine rpm between consecutive cylinder fires.  So what then?

 

I've got a single cylinder misfire that does not follow the coil or the second spark plug wire. 

The truck has new spark plugs.  even if one was bad, the other should provide adequate combustion, it being new and all.

It's intermittent, and mostly occurs before full warmup. It does it whether it is running on CNG or gasoline.  Each fuel has its own injector.

There's nothing that would make me think it is air delivery.  Changing spark inducing parts doesn't make a difference. Again, there's no reason to consider that both fuel systems are faulty in exactly the same way.  And it's intermittent, which kinda rules out a broken valve spring, low compression, or mechanical fault.

 

Arrrgh!

[Furbird]

Umm...

https://www.ford-trucks.com/forums/1659335-2015-f250-6-2-persistant-misfire-2.html

Needs a motor?

[rockmeupto125]

I forgot to mention I can't run a mode 6 scan.  I don't know why.  Perhaps its a function of the ECU flash for the CNG conversion, but it wouldn't make sense to disable any of that for CNG.

 

Iceprick, you should see these plugs in comparison to what you just suffered through.  Threaded portion is about three inches long, I swear.

[IcePrick]

A couple plugs are the cheapest parts-swapping diagnostic - but still ~$15 each.  At least pull them and take a peek.  Be happy it's #1, not #7, and not a Triton.  I think the Triton engineers were all fed into the intake of a runaway 7.3 Diesel at 13k RPMs.  At least I hope they were.

 

Compression test/leakdown that cylinder would be my next move.

[IcePrick]

3 minutes ago, rockmeupto125 said:

I forgot to mention I can't run a mode 6 scan. 

 

I recall something about this... no, actually I can't recall it, but I recall an issue about it.  I think it was an early compatibility issue in software, I would guess it has been corrected by MY2015 but we're talking about Ford here.

 

Been on Ford-trucks.com and looked around?

[Furbird]

I'm seeing several posts on there and YouTube videos that relate your issue (even after replacing all coil packs, wires, and plugs) to a broken valve spring.  I'd start by checking compression like Iceprick said as that would eliminate you breaking out the parts cannon on something that's not going to solve the actual problem.

[rockmeupto125]

I've seen that thread, and spent quite a bit of time trying to research even before I bought. My head scratcher is that it is inconsistent, and rarely occurs once the truck is warm.  There's no secondary indication of a sticking valve such as weird noise from the intake, ticking/tacking, backfire, etc. And the CNG conversion has upgraded seats, valves, and springs.  And if its mechanical, it shouldn't be intermittent.  Metal doesn't break and unbreak randomly.  But I suspect the compression test is next.  Those spark plugs are BURIED in there.

[IcePrick]

LS swap?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Too soon?

[Furbird]

I tried to help him buy a 1500HD or a Denali (whatever it was with 4WS) but they kept getting sold before I could even get freed up to get out to look at one for him.  What he NEEDS is an LBZ and just suck it up buttercup or my 4WD manual transfer case rubber floor truck in an 8.1 but they are ASTRONOMICAL now.  You can't buy a southern one anymore because we delete *.* and they've got that whole annual inspection bullshit up there.

Or, you know, FUCKING MOVE 😁

Anyway, back on topic, regardless as to how buried they are, you've got to do plugs at some point.  I had to put plugs in my 96 Firebird and I had to jack the engine over to get those mofo's out.  Spark plug wires require pulling the alternator off entirely and half the front of the engine loose.  Some of the plugs you pull from the top, some from the bottom, and some from the wheel well.  And a fat kid can't do it.  I weigh 40 pounds less than the last time I tried it so if I ever do it again it should be a lot easier 🤣

[XXitanium]

Is the red truck gone? 6 cylinder Cummins swap.

 

The code says "misfire"? ...do they have codes for inoperable valves or low compression?

 

Have you asked the gent you bought it from? (I didn't see it if you mentioned it).

Edited March 29, 2023 by XXitanium

[XXitanium]

9 hours ago, rockmeupto125 said:

The truck has new spark plugs.  even if one was bad, the other should provide adequate combustion, it being new and all.

 

...stranger things...

 

They're hard to replace?

Edited March 29, 2023 by XXitanium

[IcePrick]

I have seen marginally burned valves give inconsistent cylinder pressures - as in, the same cylinder over a series of tests sometimes having okay compression and sometimes having poor compression.

 

Also, worn or damaged ring could give insufficient compression when cold, then improve when the engine is warm.  

 

I know you don't like either one of those, although one is somewhat less crying than the other.  Gotta do the work and make us Internet mechanics stop dreaming up worst case scenarios for ya.  Look at plugs from several cylinders, get out the compression gauge, dry/wet/leakdown.  

 

When I started ripping into the 5.4, I thought it was going to be a battle to get to everything.  Now that I've done it once, it really wasn't that bad - all the tubes and hoses were quick connects, and the wiring is set up so you can't easily mis-connect stuff on reassembly.  Even removing the ECM was a breeze (yes, unless you are a small Asian child you kinda have to remove the ECM to get to #7 spark plug).  I bet once you start tearing into it, you'll be somewhat surprised with the ease of process, and with adequate blood sacrifice to the Ford gods, the result as well.  Wish I was there, I love a mystery.

[superhawk996]

Did you use Motorcraft plugs?  If they're aftermarket I'd replace them, at least on the #1 to see if that's it.  And if that does cure it do the rest of them preventatively.  Sadly, there's a fair bit of counterfeit Motorcraft parts, including plugs, floating around.  If you still have the boxes or remember what they look like, have a look online for how to spot the difference.  It's not obvious 'till you know what to look for, then it's pretty easy.

 

Check fuel trims.  Even tho a problem shown by trims being off 'should' effect all the cylinders on that bank, there's always going to be one that's most sensitive due to variables.

 

Valve springs seem to be a fairly common problem with this motor, and while that should create a consistent miss, it might depend on where the spring broke.

 

Is the miss obvious, or just triggering a fault code while it runs seemingly fine?  There was a 're-flash' to reduce the misfire sensitivity that might not have been done.

[rockmeupto125]

Motorcraft plugs that were purchased from one of the local parts houses.  Marty changed them before I bought it, he said they looked original, as in corroded as all get out, and the lower plugs were worse than the uppers.

 

At best, it's slightly auditory and a stutter that's significant for 5-10 seconds then seems to slowly and gradually resolve to running smoothly. 

At worst, the miss is obvious.  Loss of power that doesn't seem consistent with a single cylinder along with a judder and change of engine note.

 

Today I took it on an 80 mile trip.  A little stutter when getting on the highway 2 miles from the house, but didn't throw a code, and no pending codes registered.  Smooth ther rest of the trip with several stops and a couple shutoffs.

[tomek]

Just run compression and leak down tests.

This way you'll now what to do next.

[XXitanium]

Are you going to check your gas mileage, or just drive it?

 

Also, are you a proponent of seafoam?

Edited March 29, 2023 by XXitanium

[rockmeupto125]

To answer your prior question, yes, the red truck is gone, good riddance.

 

It's complicated checking mileage, but I'm trying.  It uses CNG until the pressure is too low to actuate the system, then switches to gas.  So to figure CNG mileage, you have to make sure to get it, before it runs out, and it has to have a good sized sample because of pressure changes with temperature and such.  And to figure gas mileage, it has to be run out of CNG.  Bluntly, I haven't put enough miles on it to get a good figure.

[Furbird]

I'd use something much stronger than Seafoam, like BG 44k.  I still think it's a valve spring or a seat after reading the forum posts about people having issues describing exactly what you're talking about and throwing the parts cannon at it with zero improvements.  I know it's not what you want to hear but until you get compression/leakdown testing done to make sure it's not mechanical failure, I'm afraid you might be throwing good money after bad.

[superhawk996]

2 hours ago, Furbird said:

I'd use something much stronger than Seafoam, like BG 44k.  I still think it's a valve spring or a seat after reading the forum posts about people having issues describing exactly what you're talking about and throwing the parts cannon at it with zero improvements.  I know it's not what you want to hear but until you get compression/leakdown testing done to make sure it's not mechanical failure, I'm afraid you might be throwing good money after bad.

Compression and leakdown aren't going to detect a broken spring.

[Furbird]

50 minutes ago, superhawk996 said:

Compression and leakdown aren't going to detect a broken spring.

No spring, valve doesn't seat.  Valve doesn't seat, no compression.  Video of the exact engine in question with a spring failure and the compression test diagnosed it.

https://youtu.be/jlcyzc8-o4Y?t=706

 

[XXitanium]

I knew what a leak down was, but never watched one. Great link.

 

[superhawk996]

9 hours ago, Furbird said:

No spring, valve doesn't seat.  Valve doesn't seat, no compression.  Video of the exact engine in question with a spring failure and the compression test diagnosed it.

https://youtu.be/jlcyzc8-o4Y?t=706

 

That's because their valve and piston had a fight, so of course there's no compression, and that would be the case even if the spring was perfect.  If a spring is broken but the valve hasn't been hit the compression is likely to be normal.  I've never encountered one where the broken spring wouldn't close the valve at cranking speed, hence, perfect compression.

Edited March 30, 2023 by superhawk996

[Furbird]

8 hours ago, superhawk996 said:

That's because their valve and piston had a fight, so of course there's no compression, and that would be the case even if the spring was perfect.  If a spring is broken but the valve hasn't been hit the compression is likely to be normal.  I've never encountered one where the broken spring wouldn't close the valve at cranking speed, hence, perfect compression.

Brother, they never took the head off.  That is the original valve and piston.  All they did was diag and spring swap.  They lifted the valve to close it manually to seat it for the leakdown test.  You're talking like the valve was bent.  They left all that in there, put a spring in it, and literally shipped this bitch.  Redneck mechanic 101 shit.  This is exactly what Joe is looking for to get out of this the cheapest way possible if it needs hard parts.  I'm not saying this is how it SHOULD be fixed, I'm saying this is what THEY did.

Anyway, the first one was a compression test, which is done (supposed to be, anyway) on a hot engine with peak compression to test for balance between all cylinders.  A drastic variance tells you something has ventilated.

A leakdown test is where you leave the cylinder pressurized for an amount of time to determine if the cylinder is leaking compression.  You notice they did the leakdown by pulling up on the lifter to seat the valve.  Because if they didn't, it would have failed like a mofo.

In that video, with that amount of piston damage, that engine will probably survive just fine for what they are using it for.  In a race car, that thing would scatter on the next pass and take half the engine bay with it (and probably put the car in the wall.)  In other words, Bubba using it for daily driving will get another 100k out of it.  But Cleetus McFarland ain't leaving that piston in Mullet and making another 6 second pass in a 3000 hp twin turbo engine.

[superhawk996]

A spring broken in 3 pieces isn't common.  A valve being hit by a piston and not being damaged is also not common.  Did they do a follow up after a few hundred miles to show whether the problem was truly resolved?

[tomek]

Joe said symptoms are intermittent, I don't think the valve is bent.