This is getting very frustrating

302fordracer,

Have you checked to see if there are any stored trouble codes in your computer that are related to the EGR system. If so, that could be your pinging problem.

When exhaust gases are re-circulated into the combustion chambers, they SLOW the burn rate since they are inert gases. This means that the computer has to INCREASE spark timing so that the fuel/air/EGR gas mixture completes burning at the proper time for optimum power. According to industry articles that I’ve recently read the computer advances the timing about 2 degrees for each 1% of EGR flow, up to a total of 20 degrees of additional advance at 10% total EGR flow! So, if your system is NOT re-circulating the correct amount of EGR gases and the computer still advances the timing… you’re gonna ping for sure!

How could that happen? Well, if your EGR system is either blocked or is leaking air at any point, that will cause your engine to ping since it is either not getting the amount of exhaust gas introduced into the cylinders that the computer is telling it that it is, or it is getting extra air (which burns) instead.

There are three components in our EGR systems: the EGR valve itself, the EVP (EGR valve position sensor (that screws onto the top of the EGR valve and sends an EGR valve position indication signal to the computer), and the EVR (EGR valve vacuum regulator).

The computer uses the EVR to control how much the EGR valve opens by controlling the amount of vacuum that is applied to the EGR valve diaphragm. The EGR valve should be closed at idle and at WOT, so no vacuum should be applied by the EVR. Starting at just off idle, the EVR should increase the vacuum to the EGR valve in direct proportion to throttle opening up to around 5 to 7 inches of vacuum at around 50% to 75% throttle opening. Then when you get to WOT the vacuum should drop back down to zero.

The EVR is inside the right front fender/wheel well on our cars! But, you can test it without having to get at it. Just disconnect the vacuum line from the EGR valve and hook up vacuum gauge to that line. Then open and close the throttle by hand with your engine warmed up and running and check the vacuum gauge readings.

If you've checked everything else, this is at least worth a look.

Good luck.