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A dual-fuel spark-ignition engine that was equipped with a hydrogen (H₂) port-injection and methanol direct-injection fuel-supply system was used to study the power, combustion and emission performances in a methanol late-injection strategy. The test was operated at a spark timing of a 20° crank angle before top dead center, engine speed of 1200 rpm and 1800 rpm with a manifold absolute pressure of 70 kPa and 68 kPa, respectively, and H₂ addition ratio of 0% and 3%, respectively, under different excess-air ratios. The indicated mean effective pressure decreased with an increase in excess-air ratio at an engine speed of 1200 rpm and 1800 rpm. H₂ enrichment could expand the lean-burn limits of a methanol engine without or with H₂ addition from excess-air ratio 1.6 to 2.2. H₂ addition could shorten the flame-development angle and rapid-burning angle, and advance the combustion central angle …