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I am curious. It used to be in the old days that when an O2 sensor went bad the car would run normal cold, but when warm start to run crappy. Did the or would the truck exhibit similar symptoms now? Run strong until warm up or is the whole cold running good/warm bad thing part of the past?
It still applies to the new vehicles. When you first fire up the new engines, the PCM ignores some sensors inputs (not all of them) until the engine warms up and it runs the engine in the "open loop" mode. Open loop is basically running the engine rich adjusting the idle by using the electronic throttle (no Idle Air Control valve on drive by wire cars) . When the engine and sensors are warmed up, then the PCM reads their inputs and makes adjustments in a "closed loop" manner.
10-26-2012, 11:32 AM
