Circuit Description
WARNING: This page is about a different car, the 2002 Isuzu Trooper, 2002 Isuzu Rodeo Sport, 2002 Isuzu Rodeo, 2002 Isuzu Axiom, and 2002 Honda Passport. However, it is still accessible from the selected car via links, so may be relevant.
A properly operational EGR system will directly affect air/fuel requirements of the engine. Since exhaust gas being introduced in air/fuel mixture is an inert gas, less fuel is required to maintain a correct air/fuel ratio. Introducing exhaust gas into combustion chamber lowers combustion temperatures and reduces formation of NOX in the exhaust gas. Lower combustion temperature also prevent detonation. If EGR pintle were to remain closed, eliminating EGR, air/fuel mixture would be leaner. PCM would compensate for the lean condition by adding fuel, resulting in higher long term fuel trim values.