Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
General Information: General Description
The amount of intake air flow must be inputted to PCM in order to determine the fuel injection quantity. To measure the pressure inside of the intake manifold, the MAFS is used at idle and the MAPS is required during acceleration. The MAPS (Manifold Absolute Pressure) calculates the amount of air indirectly by measuring the pressure inside of the intake manifold. This mechanism is also called Speed-Density Type. The MAPS transfers an analog output signal which is proportional to the change of the intake manifold pressure, then, with this signal and RPM, the PCM calculates the amount of intake air flow.
The MAPS is mounted on the surge tank in order to measure the pressure inside of the intake manifold, and it consists of a piezo electric element and hybrid IC, which amplifies the output signal from the element. A piezo electric element is a sort of a diaphragm using piezo electric effect. One side of the diaphragm is surrounded by a vacuum chamber while intake pressure is applied to the other side. Thus, signals are outputted by the transformation of the diaphragm, according to the change of pressure inside of the intake manifold.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.