The purpose of the study was to analyze the deposits in injectors with fuel mixture of 87 octane with percentages of anhydrous ethanol at 5 %, and 87 octane gasoline. The experimental phase was carried out in two ignition engine vehicles at a test height of 2810 msnm when traveling, each one, a distance of 3000 km inside the Metropolitan District of Quito. Two methods were applied: Stereoscopy or Vision for the analysis of the microfilters of the injectors, and the semiquantitative chemical analysis Scanning Electron Microscopy for the samples of the residues originated in the filters. In the case of Stereoscopy, in both vehicles, a reduction of clogging of the filters occurred when using gasoline with 5 % anhydrous ethanol. The Scanning Electron Microscopy allowed to conclude that there is a greater presence of the sulfur element with 4 % in the residues when using gasoline with 5 % ethanol, unlike 1 % in the waste when 87 octane gasoline is applied
