Effect of Thermal Stability of Detergents and Carrier Fluids on the Formation of Combustion Chamber Deposits

The effect of engine operating conditions on the formation of combustion chamber deposits has been studied by varying the driving cycle used in a series of vehicle tests aimed at measuring the CCD formation tendencies of different multifunctional fuel detergent additives. It was found that at higher engine temperatures it is not possible to easily differentiate the performance of different additives and that low load and low speed conditions should be chosen when testing additives for CCD control. The data obtained suggest that there is a direct correlation between the decomposition temperature of additive components as measured by thermogravimetric analysis (TGA) and their CCD formation tendencies. Of the various carrier fluids surveyed, materials based on alkyl oxides seem to perform the best in controlling CCD formation.