New techniques for the use of renewable fuels have been proposed by researchers around the world, seeking to reduce our dependence on fossil fuels and emissions of harmful gases. For compression ignition engines, fumigation stands out for allowing more significant replacements than other dual-fuel techniques, and also for not requiring modifications to the original engine structure. In this context, wet ethanol has emerged as one of the most viable fuels for port fuel injection due to its low reactivity and its renewable origin. This paper investigates the effects caused on the compression ignition engine by the use of diesel oil and wet ethanol by fumigation method and an air restriction in the engine intake through a throttle. The used engine was a small single-cylinder, coupled to an alternator, with constant load and engine speed. The fumigation fuel was wet ethanol with four different water concentrations, and different fractions of diesel oil substitution were tested. The results indicated that the use of ethanol and wet ethanol by the fumigation method increases conversion efficiency by up to 10% compared to the baseline test. However, the reduction in the intake airflow always causes a decrease in this efficiency. Intake air throttled also provided an increase in exhaust gas opacity compared to the free airflow conditions, but it is reduced when compared to the baseline test. Concerning specific emissions, carbon monoxide has higher emission levels when ethanol fumigation is used compared to the baseline condition. Under the same conditions, nitrogen oxide emissions are reduced.