any mechanics here?

[Paducah Home Theater]

Having truck troubles, don't know what to do about it.  Will try to outline it best I can.  2004 Ford F-150.  

 

1. Biggest issue is that upon acceleration, especially in a situation where I'm going at highway speeds but then press on the gas to go up a hill or pass a car without downshifting, something rattles really bad.  It sounds like you put gravel in a tin can and start shaking it hard.  

 

2. I took it to a transmission shop thinking it was the transfer case, since it also would not go in 4wd.  He said the solenoid for the apparently weird Ford 4wd system from that year was sticking so he replaced it.  Still rattled though.  He said transmission, transfer case, and axles were fine.  He put new seals in the rear axle since it has been leaking for a long time.  Recommended a tune-up.  

 

3. Took it to my normal mechanic and explained what is happening.  It also sometimes clicked in the front and had some low frequency grinding so he honed in on that.  Found that a hub had badly rusted, partially disentegrated and chunks of rust was falling off and getting on the inside, so he replaced it.  The clicking and grinding has stopped.  Still rattles though, at least when I drive it.  

 

4. This same mechanic inspected underneath and did not find any loose heat shields which is what I suspected.  

 

5. Upon actually riding with me, when I accelerated and it rattled, this same mechanic instantly said that it was a premature firing problem, Ford trucks are notorious about it, and the dealership can re-flash the computer to compensate for it.  Also said it definitely did NOT need a tune-up, for some reason.  

 

6. Problem is though, I talked to this dealership, there is no bulletin on this issue nor any issue known to them where this would actually fix such a thing.  I have an appointment for them to diagnose it but crap, this is getting old, and they don't seem to think that a need to re-flash is the issue.  

 

7. Only thing I can think of on my own is that the catalytic converter(s) has clogged and/or disintegrated, and upon acceleration under a load, the exhaust pressure is rattling a bunch of rusted junk inside of it.  I have an appointment with a muffler shop tomorrow, I guess we will find out.  It will not rattle just revving the engine though, has to be under a load.  

 

 

Any other ideas?  

Edited May 5, 2016 by MetropolisLakeOutfitters

[Wolfbane]

SNIP: "1. Biggest issue is that upon acceleration, especially in a situation where I'm going at highway speeds but then press on the gas to go up a hill or pass a car without downshifting, something rattles really bad.  It sounds like you put gravel in a tin can and start shaking it hard."

 

If this indeed premature detonation, (sounds like it is if this is not a diesel engine) I'd get that fixed asap as it will destroy your engine in short order unresolved.

Edited May 5, 2016 by Wolfbane

[JL Sargent]

Which engine is it?

[Schu]

Sounds like pre ignition to me to... take video and post it.

An uneven flame front can also make this noise as it resonates across the piston face.

[Paducah Home Theater]

SNIP: "1. Biggest issue is that upon acceleration, especially in a situation where I'm going at highway speeds but then press on the gas to go up a hill or pass a car without downshifting, something rattles really bad.  It sounds like you put gravel in a tin can and start shaking it hard."

 

If this indeed premature detonation, (sounds like it is if this is not a diesel engine) I'd get that fixed asap as it will destroy your engine in short order unresolved.

I don't understand why it just appeared out of nowhere. One day it was fine. Then I drained the transmission fluid and put a new filter in because it was whining badly when cold, I had a car that did this and a new filter fixed it. I went to test it and started to pull out at a 3 way stop just to realize a truck was coming, so I put it in reverse. Problem is, reverse wasn't primed apparently, my engine just revved up, then finally it went into gear very violently. It was fine after that, but I kept driving around the block. I gave it hell and accelerated very hard a few times after stop signs to make sure everything was ok. Drove 15 minutes to town afterwards. It started rattling at that point and hasn't been right ever since. If it is premature detonation, I don't know why it just happened to start right at this point when before there was no trace of it.

The last mechanic said to put high octane fuel in it and see if that helps it, I guess I'm about to do that here in a few minutes.

Edited May 5, 2016 by MetropolisLakeOutfitters

[Paducah Home Theater]

Which engine is it?

4.6L

[USNRET]

I agree that it sounds like pre-ignition. This can be caused by poor fuel, timing to far advanced or carbon deposits on piston tops and sometimes a lean fuel mixture.

Edited May 5, 2016 by USNRET

[oldtimer]

The problem is we don't know what it sounds like.

[MercedesBerater]

I doubt #7 is the cause. That's an easy test- rap on the catalyst and see if it rattles. In theory the catalyst should rattle more at low RPM because the pulses of exhaust gasses are farther apart allowing a rattle to happen. But the higher rpm ends up being smoother and would not have a rattle because the pulses are so minuscule it is almost like constant airflow.

If that makes sense.

I do agree with the group above with a detonation issue. It could be bad fuel, too low octane. Or - how many miles are on this engine? Have a tech pull out the plugs and replace, also while the spark bore is open, bore scope the engine and look for carbon deposits.

Carbon deposits can get super hot under load and act like a spark plug that will burn fuel as soon as it hits the combustion chamber.

I've seen that before on an older engine. Imagine a piece of charcoal burning inside your engine trumping your spark plug. All it would take is one cylinder. So check all of them.

Hope that helps! Let us know what was found.

[paul79]

Pinging?? Usually fuel related if this is indeed what you are hearing. Put some real no ethanol higher octane gas in it and see what happens. You might just be getting bad gas from somewhere.

Edited May 6, 2016 by paul79

[Wolfbane]

 

Which engine is it?

4.6L

 

 

Miles on motor? Gasoline or diesel? Not a Ford guy.

Edited May 6, 2016 by Wolfbane

[paul79]

4.6L is gas. Great motors, but they all use oil.

[WMcD]

I hope it is the fuel because it is a cheap fix.

A good buddy filled up his SUV recently and said, "The last time I paid this much for a full tank I was filling up the Miata."

BTW long ago I had a hand-me-down Toyota. It was hard to start.

Then one day I put it in a parking spot, shut down the engine and walked to the back. BBAAMM. I thought someone shot at me and ducked for cover . . . but no one was around.

I conclude the muffler or cat converter was clogged (hence hard starting like a potato in the tailpipe) and heat and fuel caused an explosion in the exhaust system. It did it a couple more times before I junked it. Maybe this will happen to you, though I hope not.

About the same time I was driving and experienced a sharp pain in my middle and a 'bang' in the car. OMG I've been shot. Actually, I was wearing a trench coat with a long belt which was out the crack in the door. The tip of the belt must have gotten under the rear wheel, pulled the rest of the belt around me and the buckle exploded as it was dragged though the crack in the door. I found the pieces of the plastic buckle.

Before that I thought Isadora Duncan was a fool. Or maybe so was I.

https://en.wikipedia.org/wiki/Isadora_Duncan

Smile.

WMcD

[Paducah Home Theater]

Which engine is it?

4.6L

 

Miles on motor? Gasoline or diesel? Not a Ford guy.

Gas, 107,000 miles.

[billybob]

Yes. I would look at the catalytic converter there for a troubleshoot. .7

Sounds like you hit upon it yourself. Self diagnosis.

Go Ford!

[Ceptorman]

Mark, MKP is a mechanic….

[CECAA850]

If you hear pre ignition your knock sensors aren't working. Theyre job is to sense knock and retard timing. Any check engine light?

[Wolfbane]

 

 

 

Which engine is it?

4.6L

 

 

Miles on motor? Gasoline or diesel? Not a Ford guy.

 

Gas, 107,000 miles.

 

 

I'm thinking as well it might be worth your time to check the combustion chamber for built up carbon deposits. Heavy carbon deposits there effectively increase compression which would require use of a higher octane fuel. You might want to fill it up with a premium gas rated at 92 or better, but as someone mentioned above, avoid gasoline with ethanol in it. Ethanol to me is like empty calories. The other thing to check is whether the computer in the vehicle is failing to adjust the ignition timing to compensate for lower octane gasoline.

 

Let us know how you make out.

[Paducah Home Theater]

I tried videoing it 5 different times this morning. The engine roar drowns out the rattle in the video, even though you can plainly hear it in person. Not sure what's up with that.

If it were predetonation, shouldn't I lose power? I mean when it starts rattling shouldn't I feel something in terms of acceleration or whatever?

Every time I type that word I want to type "predestination".

Edited May 6, 2016 by MetropolisLakeOutfitters

[Paducah Home Theater]

If you hear pre ignition your knock sensors aren't working. Theyre job is to sense knock and retard timing. Any check engine light?

No check engine light. If there were a computer code you'd think that two different mechanics who warn about an $80 charge to hook it up to a computer would have caught it, but it wouldn't surprise me.