Diesel Addict - I read this post over at the ************** web site and I thought about your pinging problem. If you sift throug all the egr stuff, it comes down to the timing as the cause the pinging?

"Besides being an emission control device and lowering the percentage of Ntrogen oxides in the exhaust, the EGR valve has the effect of diluting the fuel/air mixture and causing somewhat lower combustion temperature inside the cylinders. Also, due to its diluting effect, the pump injection timing is set slightly ahead to compensate. Same goes for gasoline engines. As a matter of fact, when an EGR valve fails closed on a gasoline engine (as due to bad vacuum diaphragm), the engine will start pinging when run on regular gas. This is due to ignition timing advanced further to compensate for the EGR effect. The solution then is to replace the EGR. A temporary fix is to run premium fuel or retard the ignition timing several degrees. Using the same logic, I would think that retarding the diesel injection pump timing by several degrees would be the correct compensation for a non-functioning EGR. You generally do not hear "pinging" or preignition in a diesel engine, but it could possibly occur."

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1995 E300 Diesel
2002 GMC Duramax CC LB 4X4