94 x pinging resolved... for now

[gitane]

My 94x has been pinging for the 3 years I have owned it. You know the regular up hill / under load pinging. Recently with the change in weather the cel coded the egr sensor was faulty. I spent 50 bucks for a new one and all of a sudden no pinging. I'm not sure of the technical reason of how an egr sensor effects pinging but in this case it worked... at least for now. Maybe some others can use this information. Many thanks to the serious explorations web site... it is awsome and has helped me in many repairs. THANK YOU.

 

[Roadrunner777]

EGR is an interesting concept. I'm as creative as the next guy, but I'm not sure I would have come up with running exhaust back through the engine for a second time, and having a computer control a valve to do it. It's amazing it works as well as it does.

Anyway, to the point, thanks for writing this thread. I get a noise under load that I am guessing is knocking... it sounds like a rattlesnake under the hood. I also thought it might be valvetrain noise from loose pushrods, but I have no evidence to support either way. I have cleaned my MAF sensor to microscopic cleanliness. Maybe I will throw an EGR sensor at it and see where that goes.

 

[mgmgmg]

I had the same problem slight ping going up hills freeway speeds. Both my DPFE and EVR were bad....Replaced them pinging gone. It been 6 months now

 

[2000StreetRod]

EGR & detonation

EGR reduces the combustion temperature and possible detonation. EGR is disabled at idle and WOT but is otherwise active when the engine is warmed up. The reduced combustion temperature allows the PCM to advance the timing for better performance. All 1st generation Explorers were equipped with Pressure Feedback EGR (PFE) that has less diagnostic capabilities than the later Differential Pressure Feedback EGR (DPFE). When the PCM detects a DPFE failure it normally disables EGR. Hopefully your pinging was mild and no damage was done to the pistons or valves. The SOHC V6 incorporates a knock sensor. When the PCM detects knock it retards the ignition timing until the knock is eliminated.

 

[gitane]

Thanks for the technical background about pinging. I hope no (significant) damage was done. The engine runs great, better fuel mileage and sounds great.