FIELD TEST OF AN EXHAUST GAS RECIRCULATION SYSTEM FOR THE CONTROL OF AUTOMOTIVE OXIDES OF NITROGEN.

A 120 vehicle field test was used to evaluate the effect of an exhaust gas recirculation system on emissions, drivability, fuel economy, engine deposits, and wear. Results indicated the following: The NO//x emissions were reduced 43% for the Comets and 57% for the Plymouths at the time of device installation. Concurrently, reductions of HC and CO, ranging from 11%-26% were also obtained. NO//x emissions remained relatively constant during the 1-year test period for the equipped fleets. However, the NO//x emissions from the control fleets declined substantially. HC emissions from the equipped Plymouths increased but there was essentially no change in concentration for the equipped Comets. The trend in HC emissions from the control groups was reversed; there was an increase for the Comets but no change for the Plymouths. Co emissions from both equipped fleets increased but remained essentially constant for the control fleets.