My car failed emissions because the NOx was really high. The guy that did the test said check the EGR, looking under the hood I found a broken vac. line between the solenoid and vac. plate, after fixing it I still have no vacuum to the EGR. By the way, I can unplug the solenoid and get vacuum all the way to the EGR, does this mean the solenoid is bad or do I have to be driving the car to reach a certain RPM before the solenoid works to let the vacuum through. Please let me know what you guys think. Thanks, Jimmy
EGR vacuum solenoid on 1991 Cadillac DeVille
by Visitor in Stockbridge, GA on April 18, 2010
ANSWER by mastertech6371 on April 18, 2010
the only time the egr is activated is when the car is under load. that is, accelaration time. the computer will pulse the egr to work and recirculate exhaust to the intake to lower the temp in the cylinders. the vaccuum line may resolve your proble. have the test re done to verify. Roy
The EGR control solenoid or EGR valve may fail causing the Check Engine Light to illuminate.