Got an error code for MAF sensor, replaced it. Next day had trouble starting car, keeping it running. Idles rough. SES light came on that day and shows P0507 and P0102 now. It runs better than before replacing the sensor, but still not right.
P0102: you need to make sure the sensor is clean; sometimes it get dirty as you are working on an old car. Check the voltage manually. Make sure there is no air leak near it
P0507: high idle... this sounds like a vacuum leak. get starter fluid and start the car. Spray around and check for change in car idle
Testimonial: "We did check for air leaks and none were found. Where do you spray the starter fluid?"
SOURCE: after changing fuel pump 2 days ago on my 97
You can test the MAF before replacing. It may be a problem with the circuit itself or just a fluke from another problem that is connected to this sensor.
There are two basic types of mass airflow sensors: hot wire and hot
film. In the first type, a very thin wire (about 0.2 mm thick) is used
as the heated element.
Components of a hot wire-type mass airflow sensor. Courtesy of Ford Motor Company.
The element temperature is set at 100° to 200°C above
incoming air temperature. Each time the ignition switch is turned to
the off position, the wire is heated to approximately 1,000°C for 1
second to burn off any accumulated dust and contaminants.
The second type uses a nickel foil sensor, which is kept 75°C
above ambient air temperatures. It does not require a burn-off period
and therefore is potentially longer lasting than the hot wire type.
A faulty MAF will cause driveability problems resulting from incorrect ignition timing and improper air/fuel ratios.
Vane-type MAF Sensors
A vane-type MAF sensor is found on many import and domestic vehicles
with EFI. All intake air must flow through the sensor. Some MAF sensors
are called volume air flow meters
A voltmeter connected to measure the signal from a MAF sensor. Reproduced with permission from Fluke Corporation.
Move the MAF sensor air vane from open to close to test it. Reproduced with permission from Fluke Corporation.
WARNING
While pushing the mass air flow sensor vane open and closed, be careful not to mark or damage the vane or sensor housing.
Ohmmeter connections to a MAF sensor. Reprinted with permission.
Resistance specifications for a typical MAF sensor with door open and closed. Reprinted with permission.
The trace of a defective vane-type MAF sensor. Reproduced with permission from Fluke Corporation.
Hot-Wire-Type MAF Sensors
The test procedure for heated resistor and hot-wire MAF sensors
varies depending on the vehicle make and year. Always follow the test
procedure in the appropriate service manual. A frequency test may be
performed on some MAF sensors, such as the AC Delco MAF on some General
Motors' products.
Satisfactory and unsatisfactory MAF sensor frequency readings. Reproduced with permission from Fluke Corporation.
A normal trace for a frequency-varying MAF sensor. Courtesy of Progressive Diagnostics--WaveFile AutoPro.
The trace of a defective frequency-varying MAF sensor. Courtesy of EDGE Diagnostics Systems.
There is also a
Mass Air Flow (MAF) Burn-Off Module Operation:
A semi-conductor control for an electronic-ignition system.
SOURCE: Why is my Grand Prix surging/stalling when ideling?
If you did not disconnect the battery and drain the voltage from the ECM, it could be using old settings when the problem existed.
When a problem occurs, the computer tries to correct it or find new settings to work around the problem. When you fix a problem you have to clear the codes and sometimes erase the memory from the computer to allow it to start back at the factory settings.
When you disconnect something and the check engine light comes on, the computer goes into limp mode and uses values for the sensors preset by the factory. The car will almost always run rich to ensure the driver can get back to a place for repairs.
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Always starts up when cold. It's only when starting a warm engine that it won't stay running.
We reset the computer and changed the air filter, which was BLACK. Still have problems starting car when engine is warm. Idles rough all the time and acts like it wants to die,
Turns out it was the after market MAF sensor. We finally bought a gm sensor and it fixed it all RIGHT AWAY. UGH. wish I would have done that 6 months ago.
We finally got it fixed. It turns out the after market MAF sensor was the problem. We replaced it with a GM MAF sensor and all problems were solved.
Just for fun, switched back to the aftermarket part and it ran bad again. So, go with the GM PART, save some headaches.
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