I have a 1997 F 150 4.2 V6 4 x 2. This past spring I had to replace the motor due to gasket failure. Now there is a pinging sound (similiar to the sound of having baseball cards in bicycle spokes or those BB gun target shooting booths at county fairs) that is extremely noticeable during acceleration. I have added octane booster and replaced the fuel filter, DPFE sensor, EGR solenoid, Mass Air flow, and the coil pack. I also tried a remanufactured computer, the truck ran worse. Another tid bit of info... unplugging the knox sensor does not set a code.

 

Is your cooling system working properly? Excess heat can contribute to pinging.

 

Are the spark plugs new? The pining you could hear could possibly be detontation from the motor running too hot. Change the plugs, then see how she runs. I reccomend Motorcraft, or Autolites.

 

I have the same problem... I have replaced my engine (4.2) and the noise is still there. I also had the rocker adjusted and then changed. The noise just seems to continue....does anyone have any other ideas??? Someone said it could be the oil relief valve but my oil pump was replaced with the engine. I appreciate any help. meh129

 

I don't think it's pinging you hear.
Ping sounds like marbles in a tin can.
Listen hard for an exhaust leak at one of the manifold ports or at the head pipe connection.
This will vary with engine speed.

 

yea pinging from detonation sounds almost like a small amount of static. You might have a manifold leak or something like that.

If it's fuel related, it's probley a clogged throttle body.Just got done doing mine yesterday on my pining and sluggish 4.6. Used 3-4 cans of throttle body cleaner and cleared out all the ports on the TB, and the truck runs like new with no pinging. Could possibly be your problem....id have to hear it to be 100% sure though.