Abstract: This study of experimental study shows the effect of ambient air temperature for four seasons in Iraq on spark ignition engine performance by using gasoline fuel. The engine was used in this resaerch has a cooled single cylinder spark ignition engine. The intake air temperature range was (10-60°C) were subjected according to the temperature changes in different seasons of the year in Iraq. The goal of that was to check the engine performance. The operation speed of the SI engine was changed from (1400-3000 rpm). The air box is provided with an electrical heater to raise the temperature of the entering air. The experimental outcomes contain a reduction in fuel consumption up to (18.9%), brake specific fuel consumption up to 15.4%, however, the thermal brake efficiency increased by about (4.4%). The exhaust gas emissions revealed a decrease almost (11%) of CO and (7.31%) of HC, however, increasing CO2 emission by (15.05%) and NOX emissions by 19.33%.