“…Marshall and Seizinger 35 found odor level increases at either high or low loads for mid-and high-speed ranges, and both the Lesley study and the Marshall study found that an oxidation catalyst in the exhaust reduced odor levels. Reading and Greeves 24 found no consistent speed and load trends with two direct injection and two indirect injection engines; and Ingram, 31 Petrow et al, 36 and Petrow and Cernansky 37 found little effect on odor intensity except during extreme operating conditions when tests using small direct and indirect injection engines were conducted. quenching.…”