94, engines pings when it has a load on it.

[410Fortune]

oh sorry, if it is detonation did anyone mention check/replace the spark plugs?
incorrect plugs, wrong gap, bad wires can cause detonation.

The base timing of the engine should be checked as well, remove the timing PIL, check timing with a light.

Everything else I can think of has been covered I believe

 

[prozachappy]

lifter tapping would be constant wouldn't it ? not just @ WOT or under load.
Good call on plugs and wires

 

[410Fortune]

No lifter tapping can happen at higher RPMS when the demand for oil is greater and yet there is none getting squirted onto the rockers...plus it all happens faster so it is easier to hear under high RPM's or under load.

its likely detonation, but I, like you, got rid of all my noises without taking the longblock apart and most 4.0L's I have had, suffered from a little of both

 

[metstalker]

alright mine is def not lifter tapping the sound mostly happens when i drop a gear and the rpms go down then i get heavy pinging like over drive at 55 mph

 

[Rhett]

Oh, you have the ping in overdrive. Yeah that is very common. If you're going to take apart the upper intake manifold, you definitely should also re-torque the lower intake manifold bolts. In fact, here's what I would do, if you haven't already:

1) run a can of seafoam thru the TB vac port. Cost you $5 and 30 mins of your time;
then drive the truck hard (drive on highway at 80 mph in D) for 20 mins; if this doesn't work, proceed to #2
2) check for vacuum leaks, inspect all vac lines, if this doesn't fix it, proceed to #3, etc.
3) replace or clean the air filter, fuel filter
4) clean MAF; inspect fuel pressure regulator vac line
5) put in 6 new Motorcraft AWSF-PP spark plugs, gapped at .054".
6) install a new set of plug wires, any quality brand (which means, NOT Accel)
7) pull upper intake, clean that, the TB, etc. with degreaser and hard work
8) retorque lower intake manifold bolts while you have the upper apart
9) possibly pull the injectors and clean them manually
10) search this site for transmission modulator and pinging

 

[410Fortune]

I agree, but I go a little further. Also replace the lower intake gasket while you are in there. Also replace the O rings and hats on the injectors (el cheapo)

This is really not a difficult project, it only looks intimidating. the upper half of the engine can be taken apart and put back together (re-sealed) in an afternoon using hand tools.