Over the past decades, researchers from different countries that produce oil or not, have intensified their research in order to develop more efficient systems. It is not unknown to the world that the main source of energy used in transport is the diesel oil, to be more economical and more efficient. For this reason, various sectors of transport and fuel producers are developing new technologies in order to replace fossil fuels with other renewable sources. Nowadays it is possible to find on the market engines that run on blends of diesel and other renewable fuels and systems that work with mixtures of ethanol and additives. To be able to use ethanol in compression ignition engines, the main problem to be overcome is the poor flammability of the ethanol under compression ignition conditions. This problem is generally attributed to the high enthalpy of vaporization of ethanol and the need for higher autoignition temperatures when compared to diesel. The option to adapt the fuel to the engine, by increasing the quality of autoignition, is typically made through the use of additives. In this work, different tests were carried out in a rapid compression machine using ignition improvers for ethanol from the use of polyethylene glycol. Tests were conducted for different start of injection instants of the mixture and different compression ratios. The results show the behavior of combustion for these different techniques for injecting fuel, with different concentrations of ignition improvers with compression ratios of 16:1, 20:1 and 25:1.