Straight vegetable oil (SVO) such as canola oil, is one alternative fuel that can be used mainly in agriculture. In this experimental engine study, a diesel engine equipped with a modern common rail system was used to determine engine modifications for canola oil operation. Due to high viscosity and high surface tension of canola oil, engines without specific modifications can cause incomplete combustion, which can lead to combustion chamber deposits and deposits at injectors and valves. This study focused on low and medium load conditions at different engine speeds. These conditions are typical for the occurrence of combustion chamber deposits during canola oil operation. At first, a comparison of carbon-monoxide (CO), total unburned hydro-carbons (THC), nitrogen oxides (NOx) and soot emissions was made for diesel fuel and canola oil operation. A cylinder pressure analysis (CPA) was carried out simultaneously to determine the difference of combustion phasing of both fuels. Subsequently, the injection parameters like rail pressure and injection timing (Start of Energizing, SOE) for five operation points were adjusted to improve combustion and avoid deposits in the cylinder. (C) 2015 Elsevier Ltd. All rights reserved.