This work was conducted in order to study the effect of Combustion Chamber Deposits (CCD) on engine-out hydrocarbon emissions. A bench engine test based on the CEC-F-20 test procedure was used to accumulate CCD. The experiments were performed on a 2.0 L, four-cylinder engine with multipoint fuel injection. All measurements were carried out under steady state operating conditions at full load on the engine.The measurement of exhaust hydrocarbons was accomplished with a fast-response FID analyser, with the sample probe being installed close to the exhaust valves in the exhaust port of cylinder #1 and #4, respectively. Interpretation of the measurements was based on the typical hydrocarbon curve measured by the fast FID during the exhaust phase of the combustion cycle.In order to emphasize the CCD effect, three pure component fuels of differing volatilities were used. Test results indicated that CCD gave an increase of total HC amount. The effect of the squish area deposits were considered separately from total CCD; the results showed that deposit formation in the squish area can critically impact the combustion process.Additional measurements were accomplished to assess the effect on engine-out HC emissions of fuel absorption/desorption by the cylinder wall oil layer using two different base oils (mineral and synthetic).The experimental results appear to confirm a suspected role of fuel solubility in engine oils.