Bad Engine Ping, no codes!

[arjbeauch]

I am getting really bad engine ping even at low speeds starting at 18mph and up. Under heavy acceleration ping is minimal but moderate acceleration the ping is awful. I have fought this since I have owned this vehicle. Its a 2000 3.8 Windstar with 113,000 mi. I have had all recalls , isolater bolts, valve cover, ecu program, checked IMRC rods and repaired, just removed intake recently and cleaned egr ports. Three were completely plugged. Installed new plug wires because I was getting shocked when I got near them. They were original. New spark plugs at 100,000 miles. I have been testing the DPFE with a meter and get .98 volts at idle and 1.1 at high rpm. This doesnt seem right. I checked with the engine at operating temp. When I apply vacuum at the EGR valve I can stall the engine. Will the egr open at high rpm while parked? I am really at the end of my rope on this problem and would love to find a solution! Thanks in advance for any help everyone can offer. The check engine light is finctional.

[wiswind]

It is possible that you still have some sort of vaccum leak someplace, but not serious enough to set a code.
This would be air entering the intake at some point past the Mass Air Flow (MAF) sensor.
Verify that things are secure......the PCV line to the front valve cover, the breather line to the rear valve cover......connecting to the flex hose......all the vaccum lines that connect to the back side of the upper intake manifold.....etc.
Also....verify again.....that the IMRC shafts are both connected to the IMRC actuator....a common cause of pinging when one/both is not connected.

Hopefully, you used the Motorcraft or Autolite double platinumn spark plugs......the multi-prong Bosch spark plugs have been noted as not doing so well in the windstar application.

If the EGR system is not flowing correctly, you should get a code.
Short of that, it could be the DPFE sensor.....but that would be replacing it as a guess.
The EGR system should not activate when the vehicle is not being driven (reving the motor in the driveway is not a good way to activate it).

Other possibility would be fuel pressure or flow......fuel filter, vaccum line to the fuel pressure regulator leaking could be a possible vaccum leak source.
Regulator seems to not be high failure.

Those are just some guesses of the top of my head.