MAP sensors contain no moving parts, and they don’t typically wear out, but cleaning the MAP sensor may be required if it’s contaminated by carbon or other deposits from the engine. Repeat the test and note that as you draw and release vacuum/pressure, the voltage should respond instantly. Using the vacuum pump, you should see voltage drop to around 1 V at 20 inHg vacuum. The typical MAP sensor should read around 4.7 V when open to the air.
2008 duramax mass air flow sensor problems manual#
Either way, check your repair manual for the wiring diagram and specific voltage readings. Turbocharged engine MAP sensors will also respond to pressure, and their pressure/voltage readings may be different. With the MAP sensor connected and the ignition in the “on” or run position, check the voltage output on the MAP sensor signal wire. First, remove the vacuum line or remove the MAP sensor from the intake manifold. You can easily test a MAP sensor with a vacuum pump and multimeter. The MAP sensor continuously measures the pressure/vacuum in the intake manifold. In some vehicles - older K-cars, for example - the MAP sensor is mounted by the ECM, connected to the intake manifold via a long vacuum hose. The MAP sensor is usually mounted directly to the intake manifold, somewhere after the throttle body, though some are mounted on the firewall or elsewhere in the engine bay, connected to the intake manifold via a vacuum line. You can usually tell if you have a MAP sensor if you cannot find a MAF sensor in the intake air tube before the throttle body. Some turbocharged engines use both MAF and MAP sensors. Air mass is a critical measurement the ECM uses to calculate fuel injection, and most engines are either equipped with a manifold absolute pressure (MAP) or mass air flow (MAF) sensor. In fuel-injected engines, the engine control module (ECM) calculates fuel injector pulse based on several other sensor readings, such as engine RPM, engine coolant temperature (ECT), intake air temperature (IAT) and air–fuel ratio (AFR), among others. MAP sensor cleaning may be necessary if you’re experiencing poor fuel economy, rough idle, hesitation or stalling on acceleration, or an illuminated check engine light. These deposits can cause many problems, such as interrupted air flow, fouled spark plugs or fuel injectors, engine overheating or skewed sensor readings. Even a well-maintained engine will collect deposits of dust, dirt, grime, carbon and oil - both inside and outside.