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Four Cylinder

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The milestone breakthrough for altitude and fuel metering was fuel injection with electronic fuel-and-spark management. Jeep was among the earliest 4WD platforms to use EFI. Here is the 1987 YJ Wrangler 2.5L four-cylinder with TBI. The feedback sensors, including an oxygen sensor and manifold pressure sensor, enabled the electronic control module to instantaneously adjust fuel flow and spark timing to meet various engine loads and atmospheric conditions.