Slight miss

[Fitts07]

So i have a 2011 expedition about 125k miles on it. Had it for a little over a year. Love the truck. Ive put about 25k miles on it. It developed a slight miss or tiny stumble on a 2k mile road trip about 8 months ago thats never gone away.

I have a slight miss at cruise at almost any speed and the engine is not fluid through the rpm range if i get in it. The miss is barely noticeable most of the time but when i lean on the throttle before and after the first shift its a little more noticeable.

Sometimes the idle is a bit rough, i thought that was pretty normal though for the 5.4.

No check engine light, very few misfires here and there on random cylinders with my torque pro scanner. Nothing on forscan.

I have done the following maintenance / repairs (the miss has never improved or gotten worse during any of this)
New OE plugs from ford (no fakes lol)
MSD street fighter coils
Changed all fluids (engine oil, power steering, transmission, rear axle, coolant and brakes)
Full Timing set with ford parts
M360hv oil pump
New thermostat, radiator cap and water pump
I run penzoil 5w30 ultra
New battery

Any ideas? Not sure where to look next, possibly injectors? I took it to a local shop, they could feel what i was talking about but couldnt find anything wrong.

 

[Timo2824]

What is your fuel pressure at the rail when the miss is happening? It may be fine during a static test, but when you're accelerating it may not be flowing enough fuel.

 

[mr_dave]

Sometimes the idle is a bit rough, i thought that was pretty normal though for the 5.4.

Definitely not normal. My idle at 550rpm is as smooth as glass.

The next thing I would look at is fuel delivery - pump, filter, etc.

It could also be a roller follower issue. Were all of those thoroughly checked when the timing job was done? Does it have a loud ticking or tapping noise at idle?

 

[Fitts07]

Ill check pressure today while driving and see what happens.

I checked all the followers, nothing loose or jacked up looking. I did the timing job without pulling any. Engine idles super quiet but a little rough sometimes, all i can hear is the injectors.

 

[Trainmaster]

Fuel pressure as mentioned. This might show a bad pump or screen. Don't think the 2011 has a filter?

"MSD street fighter coils" ?? Unless the problem existed before you installed these Chinese dragon-breath contraptions, I'd ditch them, bite the bullet and install something real OEM. I assume you've had the problem before they came?

 

[mr_dave]

The filter is integrated with the pump inside the tank. https://www.fordpartsgiant.com/parts/ford-sender-and-pump-asy_9l1z-9h307-d.html

Also, check the injectors. If you look around you can get a full set of Bosch injectors for a little over $200.

 

[Fitts07]

Fuel pressure as mentioned. This might show a bad pump or screen. Don't think the 2011 has a filter?

"MSD street fighter coils" ?? Unless the problem existed before you installed these Chinese dragon-breath contraptions, I'd ditch them, bite the bullet and install something real OEM. I assume you've had the problem before they came?

Yea no serviceable fuel filter on this one. Its a "lifetime" filter in the tank. Which is more like till the end of the warranty.

Yea the miss was there before.

 

[Trainmaster]

Yea no serviceable fuel filter on this one. Its a "lifetime" filter in the tank. Which is more like till the end of the warranty.

Yea the miss was there before.

Fuel pressure, then injectors and their connectors?

 

[Fitts07]

Im having trouble finding a fuel pressure tester that will work. My harbor freight one is a pos that just went in the dumpster. The one i rented from autozone leaked really bad.

Anyone have a recommendation?

 

[Trainmaster]

What made you do the timing set and change the coils? I've used cheap fuel pressures gauges and never had a problem with them. Maybe just lucky.

Go back to when the problem developed. What work did you do when it was last ran right? If it ran well before the timing set was changed, you could have a vacuum leak? Have you cleaned the MAF and throttle body?

This may not be helpful, but remember that by far the most common cause of any misfire is bad plugs, bad coils or bad plug gapping.

 

[Fitts07]

I had to do the timing set because of bad tensioners. Had really bad chain rattle on startup.

The miss developed in the middle of a 2k mile road trip. Prior to leaving i had changed the plugs (bought from the dealer), air filter and changed the oil. I changed all coils halfway home thinking one or more coils might be getting weak. Its never gotten any better and i feel like its very slowly getting worse. MAF and throttle body are clean, also just normal paper air filter not an oiled one.

 

[Trainmaster]

If this was my problem, I would replace the plugs again. They are cheap and the problem surfaced after you changed them. Sounds like that's all you did before the miss began. I'm assuming you replaced the rubber boots too when you did the plugs? Just my two cents.

 

[Fitts07]

So i finally found a gauge that doesnt leak.

I have 50psi with the key on engine off, it builds instantly when the key is rolled.

55psi running, only varies by 1 or 2 psi either way. Same pressure when the miss is present or wot.

Drops to 30psi after sitting for an hour.

I've replaced the plugs 3 times since this issue started, all with dealership purchased ones.

 

[mr_dave]

Injectors would be my next guess. Both the injectors themselves and electrical connections. For example, I had a previous vehicle where one of the injector wires was rubbing on a metal bracket and eventually wore through the insulation, causing a (very difficult to find) short and intermittent misfire.

If you can narrow down the cylinder that would help a lot. Then you can move around things like injectors and coils to narrow down the issue.

 

[Fitts07]

I ordered new bosch injectors. I was leaning towards them too.

The trouble is what feels like a stumble or miss doesnt center on a particular cylinder. I get a few on almost every cylinder while driving. It feels like the computer is missing a lot of them.

 

[mr_dave]

That sounds like it could be a poor electrical connection somewhere, or bad ground.

 

[Fitts07]

Well i got rear-ended on the way home from work on friday. Being a 2011 i think she might be totaled. Guess ill be returning my injectors lol.

 

[Motorcity muscle]

Sorry to hear about accident. Problems like this need a good code reader, not the standard auto parts tool. Can use to diagnose problem and not change good parts for cheap parts that cause more issue's.

 

[Hamfisted]

Well i got rear-ended on the way home from work on friday. Being a 2011 i think she might be totaled. Guess ill be returning my injectors lol.

That's why I leave the trailering ball in the hitch. It's saved my Expy a few times. But yours looks repairable if you want to. Just find one that was totaled from front end damage but still has the good liftgate and rear bumper. Not too bad a repair. You can probably even find one that color matches.




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[Fitts07]

That's why I leave the trailering ball in the hitch. It's saved my Expy a few times. But yours looks repairable if you want to. Just find one that was totaled from front end damage but still has the good liftgate and rear bumper. Not too bad a repair. You can probably even find one that color matches

I honestly just pulled my triple ball hitch with a hook on it off like the day before lol.

Yea i might do that, its been a good truck and has low miles.