I have a 98 f-150 4.6L 5spd that has a wierd rattling noise coming from what sounds like the engine. The noise will only happen when the truck is in gear and under a load. It will not happen if I keep the RPM's low, unless I am going up a hill. When I rev the truck in neutral, the rattling noise isn't there. Also when I'm driving and hear the ratling noise it will go away when i push the clutch in(which im guessing takes the load off) but will come back when i let out on the clutch. Seems to happen most when I'm in gear and trying to accelerate. Any help would be much appreciated!!!
Thanks.

 

New plugs and mid grade fuel might fix it. Probably detonation happening or alot of carbon build up on the valves.

 

Thanks. I am definitly gonna start there. I will post again and let you know how it worked!!!

 

If you've never replaced the plugs on a Triton before do research on how to do it. Make sure the motor is overnight cold, vacuum out the plug holes before pulling, use plenty of penetrating oil, and make slow 1/4 turns. Don't over tighten when replacing them and fill the spark plug boots with dielectric grease.

 

Hey there,
I replaced the plugs and the wires and it still has a rattling sound when accelerating or under load. Could it be a partially blocked catalyic converter causeing this rattle. I am also getting p0171 and p0174 error codes.
Thanks.

 

drive the truck until running on fumes and fill it with the high octane fuel. mine does that when it runs on regular. id almost guarantee it will fix it.

 

I have the notorious exhaust stud rusted away issue and my truck sounds it's worst when I pedal down. Might want to take a look at your exhaust manifolds.

 

Mine did this for years. Bought in 2000 with 28,000 miles on it. Fast forward to 2017. Still runs strong with 192,000 miles still with original engine and transmission. Been running 87 octane for years. Even filled up with Shell 92 octane only and still the engine rattled under load (Sounded like metal ball rattling around in a spray paint can). Never rattles when revving engine in neutral. Waited until I was running on low fuel light. Threw some NOS Racing formula Octane Booster 12010 and 22 gallons of Shell 92 octane. Cleared that rattling under load noise completely, the same day. Thanks for the hot tip. Much appreciated.

 

Those error codes indicate a lean condition on both banks. Vacuum leak, bad maf are probably the most common. The computer monitors the o2 sensors as well as others and adjusts fuel trims. If the maf is dirty you'll get false readings which lead to this. If there's a vacuum leak it'll throw extra fuel at it to compensate and kick those codes as well. You'll need to look at fuel trims to really get an idea what's going on.

 

I second what sycoholic said, same thing on my own truck. cleaned the maf with the crc maf cleaner and found my vacuum leak, no more ping/rattle.

 

Im having same noise in mines tried alot of things gone try that next but mines did it less when i got my rear ac door actuators replaced and when i turn it off and accelerate i hear it. I have 2003 expedition 5.4 4wd

 

The noise is due to ignition timing to far advanced for the amount of fuel in the air to fuel mix ratio or any cause of Leanness.
The noise is the heads and block, rods and crank, ringing from cylinder pressures to high.
This comes about because the cylinders are being fired to soon before top center. that results in the cylinder pressures 'peaking' too near piston top dead center when the crank and rod are to near 'straight alignment' and cannot go any where from the pressure. The cylinder pressures is too high and slams the rest of the engine as the Knock you hear.
This is hard on the bearings, pistons/rings, rods, crank and head gaskets.
It is not a normal condition for these engines unless something is the cause.
The total design was made for 87 octane rated gas.
The 4.6 and 5.4 engines are equipped you Knock sensors.
Their intent is to pull ignition timing back when ping and knock is detected .some 8 to12 degrees then return to normal when knock is no longer detected to protect the engine from damage as described above.
Questions are:
1. Is there a Knock sensor code set.?
2.Are there any other codes indicating a lean intake system?
3. Is there enough fuel pressure so the engine does not run Lean?
4. The Mass Air meter might be dirty or faulty with or without a code set.
5. Has any one used a Scanner to watch the timing when Knock or Ping occurs?
6. Is the EGR valve leaking exhaust gas under acceleration when it should not be open? This will cause ignition advance.
Without proper diagnostics your all gambling.
Do it right.
An example of this is the wise guy Diesel owner who installs a chip to get huge torque gains then ends up losing an engine from to much fuel timing.
It shows up as a huge chunk of block missing.
A Diesel runs 22 to 1 compression +/- so you can see what can happen when playing with something they don't understand...


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