Run some tests on the Mass air flow sensor.
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, generated by the sensor when the incoming air cools the hot wire, to the ECM. The signal is used by the ECM to calculate the injector pulse width, which controls the air/fuel ratio in the engine.
See Figures 1, 2, 3 and 4
Fig. 1: Backprobe the connector at terminal B as shown (1993-94)
Fig. 2: On 1995-98 vehicles, backprobe terminal 1 for testing
Using a multimeter, check for voltage by backprobing the MAF sensor connector, as illustrated.
Fig. 3: To backprobe the connector, remove the rubber boot from the back of the connector
With the ignition switch ON and the engine stopped, voltage should be less than 1.0 volt.
Fig. 4: The voltage should be less than 1 volt with the key in the ON position
With the engine idling at operating temperature, voltage should be 1.0-1.7 volts.
With the engine running at approximately 2,500 rpm, voltage should be 1.5-2.1volts.
It is important to watch for a linear voltage rise in response to increases in engine rpm, up to about 4000 rpm.
If voltage is not within specifications, check the power and ground circuits.
If the power and ground circuits test okay, the MAF sensor may be faulty.