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chris 10/7/2012

1999 Pontiac Grand Prix GTP 6 Cyl 3.8L


mass air flow problem

i had a problem with my car stolling out and i unplugged the maf sensor and it worked,when i got home my friend had a extra one but it was a bit shorter than my original one it works fine car doesnt stall out anymore but gas mileage really sucks,could that be the problem thanks chris

2 Answers


CVO 10/7/2012


The Mass Air Flow (MAF) sensor directly measures the amount of air flowing into the engine. The sensor is mounted between the air cleaner assembly and the air cleaner outlet tube.

The sensor utilizes a hot wire sensing element to measure the amount of air entering the engine. The sensor does this by sending a signal, which is generated by the sensor when the incoming air cools the hot wire, to the PCM. The signal is used by the PCM to calculate the injector pulse width, which controls the air/fuel ratio in the engine. The sensor and plastic housing are integral and must be replaced if found to be defective.

The sensing element (hot wire) is a thin platinum wire wound on a ceramic bobbin and coated with glass. This hot wire is maintained at 392°F (200°C) above the ambient temperature as measured by a constant "cold wire''.

A faulty MAF sensor due to loose connections, bad grounds, high resistance in the circuit, or opens in the circuit can cause the following symptoms.

Related Symptoms

A no start condition
Stalls at idle
Surging idle
Extended crank time when engine is cold
Poor fuel economy


With the engine running at idle, use a DVOM to verify that there are at least 10.5 volts between terminals A and B of the MAF sensor connector. Such a reading indicates that the power input to the sensor is correct. Then, measure the voltage between MAF sensor connector terminals C and D. If the reading is approximately 0.34–1.96 volts, the sensor is functioning properly.


CVO 10/7/2012

Additional info.

The MAF sensor produces a frequency signal which can be monitored using a scan tool. The frequency will vary within a range around 2000 Hz at idle to about 10,000 Hz at maximum engine load.

A technician's scan tool reads the MAF value and displays it in grams per second (gm/s). At idle, it should read between 4 gm/s-7gm/s on a fully warmed up engine. Values should change rather quickly on acceleration but values should remain fairly stable at any given RPM.


HouseCallAuto 10/7/2012

Get the right sensor. You can't just stick any sensor that fits the screws in there and expect it to work. OMG


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