I have a 2010 4.6 that has developed a weird rattle initially with cruise control.

You would set the cruise, after 5-10 miles you could hear this rattle that kind of sounded like detonation.

It has recently started doing it without the cruise as well. This morning it did it accelerating down an expressway ramp, without cruise.

I had a major tune-up around 85,000 miles, I am at 109,000 now.

It will stop immediately if there is any change in throttle position, such as accelerating or decelerating.

Anyone have any ideas? Been doing it for over two years, the dealership said they have no idea what it is.

I also have developed a hard shifting transmission. The trans when you kick it down during passing, shifts so hard you would think something broke inside. The dealer has pulled the pan, said there are no codes, everything looks good, has no idea what is wrong with it either.

Looking for suggestions.

 

Does it rattle with premium gas?

4 speed or 6 speed transmission? 2 valve or 3 valve 4.6?

Did the major tuneup include MOTORCRAFT spark plugs?

 

I never run premium gas. 6 speed, not sure if it's 2 or 3 valve. How do I tell?

I sure hope it did, I had the Ford Dealer do it. (plugs)

 

If it's a 6 speed, it's a 3 valve.

TRY premium gas (93 if you can get it) for troubleshooting purposes - if it stops rattling, it's spark knock. That's usually caused by combustion chamber deposits, you may need a BG or Motorvac intake cleaning job. Or - it may have a bad knock sensor.

Go back to the dealer and have them research TSB's on the transmission. The 6 speed had a lot of software updates, quite a few of them to fix poor shift quality.

 

They have re-flashed the transmission three times, said give it time to learn. Usually lasts only a few weeks. Then it's back to the hard shifting scenario.

 

What kind of fuel are you running? Sure sounds like its pinging from crappy fuel. Maybe try to find a Shell or Chevron station and fill it up.

 

I don't think it's spark knock. It almost sounds like a relay chattering.

I will try better gas next fill up in a day or two.

 

One tank of 91+ will prove or disprove the spark knock theory.

 

I am going try that, but as of this morning, I think it's mechanical, inside the engine.

As I was getting coffee and driving along side McDonalds, I could hear a lighter version of it.

 

If you hear it in a drive-through, it may be cam phasers.

 

For as much noise as they make, I am thinking you may be correct.