GM 22048269 Pulse Air Valve

To reduce nitrogen oxide (NOX) emissions, the Exhaust Gas Recirculation (EGR) system recirculates a small amount of exhaust gas into the combustion cycle to lower peak combustion temperatures where NOX is formed. There are exhaust passages in the intake manifold that facilitate efficient removal of exhaust gases. Vacuum hoses and EGR valve checkup are the main maintenance points, with TVS monitoring vacuum signals according to temperature changes in engine. Two types of EGR valves exist: vacuum modulated and exhaust back-pressure modulated, both with different ways of opening the valve. The EGR system is governed by throttle position and engine temperature so as not to allow recirculation at idle, during deceleration or when starting from cold condition for maintaining appropriate air fuel mixture. Rough idle is among the most common problems associated with this system, stalling and poor performance being others these can be solved through diagnosis and replacement of certain parts other than that. Diagnosis will involve; checking EGR valve movement; testing vacuum signal integrity and TVS functionality. Where need be, one can substitute either EGR valve or thermal vacuum switch referring to proper procedures for installation purposes.