Oil from an incorrectly serviced aftermarket performance filter will also foul the MAF sensor.MAP sensor problems could trigger a DTC and check engine light. As for paper, keep in mind poor-quality air filters often shed paper fibers that accumulate on the heated wire and resistor assembly. Dirt not only fouls the MAF sensor, it also clogs the idle air control (IAC) and will rapidly wear upper engine cylinder parts. Dirt is introduced into the engine intake air stream when the air filter is perforated or incorrectly installed. In these applications, the PCM will store a P0100 through P0104 MAF-related trouble code.Īs mentioned above, dirt, paper and oil contamination cause the majority of MAF sensor failures. Because some manufacturers like GM incorporate a manifold absolute pressure (MAP) sensor to measure intake manifold vacuum, their systems can revert to speed density operation when their MAF sensors malfunction or lose their calibration. Some MAF sensors, like those used in General Motors and other corporate platforms, generate a frequency signal that’s sent to the PCM. During the early 1980s, engine computer management systems relied upon a speed density fuel system that used inputs from a throttle position, engine speed, intake air temperature, and manifold absolute pressure (MAP) sensor to estimate the grams per second of air flowing into the engine. Armed with this knowledge, it’s entirely possible that you can provide an alternative solution to your customer’s problem.Īutomotive engineers know that 14.7 grams of air must be mixed with 1 gram of fuel to achieve nearly perfect combustion in a modern engine equipped with a catalytic converter. If you understand that a defective mass air flow (MAF) sensor can cause an extremely lean condition by underestimating the amount of air flowing into the engine, then you can understand how a defective MAF sensor can be mistaken for a defective fuel pump assembly.
Let’s say that an amateur mechanic believes the P0171 “system too lean, bank one” trouble code that he retrieved with his code reader indicates that the fuel pump you sold him a month ago is defective.
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