Northstar Engines and System Technical Discussion Discussion, EGR symptoms in Cadillac Engine Discussion; What are the symtoms of a sticking egr, car is surging a little new coils could possibly be a fouled ...
Automobile(s): 2002.5 F55 STS, 2014 Explorer XLT 4WD
MD Eastern Shore
Re: EGR symptoms
Another symptom of a sticky EGR valve is a brief, minor ignition "rattle" on part-throttle acceleration or a low pitched ignition ping during moderate part-throttle such as going up a slight grade. And, as Ranger said, a partly open EGR will trash the idle characteristics.
It is entirely possible that a surge could be present also, as when EGR operates it dilutes the incoming air (oxygen) charge in order to control combustion temperatures: excess exhaust gas from a fluttering EGR would upset the fuel/air mixture.