how to clean mass flow air sensor

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Mass Airflow MAF Sensor

Mass Airflow MAF Sensors

Mass airflow sensors (MAF), which are used on a variety of multiport fire injection systems, come in two basic varieties: hot conducting wire and hot film. Though slightly different in aim, some types of sensors measure the volume and density of the air entering the engine so the computer can calculate how much fire is needful to preserve the correct fuel smorgasbord.

Mass airflow sensors have no moving parts. Unlike a weathervane airflow meter that uses a outpouring-loaded pother, mass flow of air sensors purpose physical phenomenon stream to measure flow of air. The sensing element, which is either a Pt wire (hot wire) or nickel note foil grid (hot moving-picture show), is heated electrically to keep information technology a certain amoun of degrees hotter than the incoming air. In the case of active film MAFs, the power system is heated to 75 degrees C. above incoming ambient air temperature. With the thermal telegram sensors, the wire is heated to 100 degrees C. above ambient temperature. As air flows past the sensor, information technology cools the element and increases the current requisite to keep the element hot. Because the temperature reduction effect varies directly with the temperature, density and humidity of the incoming melodic phrase, the amount of current needed to keep the element flaming is directly proportional to the air "pile" entering the engine.

MASS AIRFLOW SENSOR OUTPUT

MAF detector yield to the calculator depends on the case of sensor used. The hot wire version, which Bosch introduced binding in '79 on its Luteinizing hormone-Jetronic fuel injection systems and is in use connected a number of multiport systems including GM's 5.0L and 5.7L Tuned Port Injectant (TPI) engines, generates an analog voltage signal that varies from 0 to 5 volts. Output signal at idle is usually 0.4 to 0.8 volts increasing adequate to 4.5 to 5.0 volts at blanket open throttle.

The hot film MAFs, which Atomic number 89 Delco introduced in '84 happening the Buick turbo V6 and induce since used on the 2.8, 3.0 and 3.8L V6 engines, produce a square wave variable frequency end product. The frequency roam varies from 30 to 150 Hz, with 30 Hz being average for stagnate and 150 Hz for wide open throttle.

Mass Airflow MAF Sensor digital waveform

Another difference between the hot wire and hot film sensors is that the Bosch hot electrify units have a self-cleanup cycle where the platinum wire is heated up to 1000 degrees C. for one second subsequently the engine is shut down. The momentary surge in current is controlled by the onboard computer through a relay to sunbur off contaminants that might otherwise foul the wire and interfere with the sensor's power to read incoming air mass accurately.

MASS Flow of air SENSOR DIAGNOSTIC FAULT CODES

An engine with a bad MAF sensor May start and stall or be hard to start, it Crataegus oxycantha waffle under load, idle rough operating theater run to a fault deep or lean. The engine Crataegus oxycantha likewise hiccup when the throttle abruptly changes position.

Much, a dirty or faulty MAF sensor will cause the engine to set a Shrivelled code and turn on the Check Engine Light. If the MAF detector wire becomes dirty operating room is contaminated with oil (from an aftermarket reusable air filter), it will be slow to respond to changes in airflow. This may cause the MAF sensor to under-study flow of air, causing the engine to run tip over.

On OBD II vehicles, the input from the MAF sensor is combined with those form the throttle location sensor, MAP sensor and engine speed to calculate locomotive engine laden. If your scan tool can display calculated locomotive load, look at the value to see if the lading is low at idle, and high when the engine is running nether load. No change in the reading surgery a reading that makes no sense could indicate a trouble with any of these sensors.

If you suspect a MAF sensor problem, scan for any fault codes. Trouble codes that Crataegus oxycantha indicate a problem with the mass airflow sensing element include:

P0100....Mass or Book Airflow Circuit

P0101....Mass operating room Volume Flow of air Circuit Range/Operation Problem

P0102....Masses operating theatre Volume Airflow Circuit Low Input

P0103....Lot or Loudness Airflow Lap High Input

P0104....Mass or Volume Air Feed Circuit Periodic

P0171....System too Inclination (Bank 1)

P0172....System too Rich (Bank 1)

P0173....Fuel Trim Misfunction (Depository financial institution 2)

P0174....System of rules too Lean (Bank 2)

P0175....System too Rich (Camber 2)

On sr. Pre-OBD II vehicles, you can function a scan tool or manual trashy code procedure to read the codes:

Gramme Pre-OBD II: Inscribe 33 (too high frequency) and Code 34 (too low absolute frequency) happening engines with multiport fuel injection only, and Code 36 on 5.0L and 5.7L engines that use the Bosch calorifacient wire MAF if the burn-off bike after squinting-down fails to pass.

Henry Ford Pre-OBD II: Code 26 (MAF out of range), Code 56 (MAF production too high), Code 66 (MAF outturn as well downhearted), and Code 76 (no more MAF change during "zany" test).

Course, Don River't overlook the bedroc, too so much as engine compression, vacuum, fuel pressure, ignition, etc., since problems in whatsoever of these areas keister grow similar driveability symptoms.

MASS AIRFLOW SENSOR Diagnosing

Unlike vane airflow meters with their transportable flaps, MAFs have no moving parts so the merely way to know if the social unit is up decently is to look at the sensor's output, or its effect on injector timing.

With the Bosch hot wire sensors, sensor voltage output fanny exist record instantly with a digital voltmeter away probing the apropos terminals. If the electric potential readings are out of range, or if the sensor's voltage output fails to increase when the throttle is opened with the engine running, the sensor is bad and needs to be replaced. A dirty wire (which may be the result of a defective soul-cleanup circuit or external contamination of the electrify) can make the sensor slow to respond to changes in flow of air. A broken operating theatre burned out telegram would obviously prevent the sensing element from working at all. Major power to the MAF sensor is provided through a copulate of relays (one for power, one for the burn-off cleaning cycle), so check the relays first if the MAF sensor appears to be dead or sluggish.

Along GM MAF sensors, there are a few quick checks you can do for vibration-related sensor problems. Bind an analog voltmeter to the appropriate MAF sensor production terminal. With the engine idling, the sensor should be putting out a rock-steady 2.5 volts. Tap light on the sensor and note the meter version. A well sensor should show no change. If the analogue needle jumps and/or the engine momentarily misfires, the sensor is bad and needs to be replaced. You can also chit for heat-agnate problems past heat the sensor with a hair dryer and repeating the test.

This same test can also constitute done using a meter that reads frequence. The older AC Delco MAF sensors (the likes of a 2.8L V6) should show a sweetheart reading of 30 to 50 Hz at idle and 70 to 75 Hz at 3,500 rpm. The later model units (like those along a 3800 V6) should read about 2.9 kHz at idle and 5.0 kHz at 3,500 rpm. If tapping on the MAF sensor produces a unforeseen change in the frequency signal, it's time for a brand-new sensor.

Happening the GM sulfurous film MAFs, you can also tap into the onboard computer data stream with a glance over joyride to read the MAF sensing element turnout in "grams per second" (GPS). The reading might go from 3 to 5 GPS at idle up to 100 to 240 GPS at wide susceptible throttle and 5000 RPM.

The scantool GPS reading at idle will vary away locomotive engine shift. The larger the engine, the high the GPS reading at idle. The GPS inactive reading will about correspond to engine displacement in liters. A 3.0L V6 engine, for instance, will generate a Global Positioning System reading of about 3.0 grams per second at idle. A larger 5.0L V8 would read around 5 grams per second, and a smaller 2.0L quaternion cylinder would interpret around 2 grams per second at idle.

Some fomite manufacturers publish MAF sensor GPS reading specifications for specific engine speeds. The locomotive engine is held steady at the specified RPM to compare the scantool GPS reading to the spec. If the Reading is off by much 10 percent, the MAF sensor is not reading airflow correctly. The cause could be a dirty sensor that needs to be cleaned.

Like throttle position sensors, there should be smooth rectilineal modulation in sensor yield passim the rpm range. If the readings jump all concluded the put back, the computer North Korean won't be able to deliver the right bare/fuel mixture and driveability and emissions will suffer. Sol you should also find out the sensor's output at various speeds to get wind that information technology's output changes appropriately. This nates cost finished by graphing its frequency yield every 500 revolutions per minute, or by observing the sensing element's wave form on a scope. The waveform should embody aboveboard and demonstrate a inclined increase in frequency arsenic engine focal ratio and load increase. Any skips or sudden jumps or excessive noise in the pattern would tell you the detector needs to be replaced.

Another way to check MAF sensor output is to check what effectuate it is has on injector timing. Using an oscilloscope or multimeter that reads milliseconds, connect the test investigation to any injector ground period of time (one injector terminal is the supply voltage and the new is the ground circle to the computer that controls timing). Then face at the duration of the injector pulses at idle (operating room while cranking the engine if the locomotive North Korean won't start). Injector timing varies depending on the application, but if the mass air flow sensor is not producing a signal, injector timing volition be about fourfold longer than normal (possibly making the fuel mixture too rich to start). You can also use millisecond readings to confirm fuel enrichment when the throttle is opened during acceleration, fuel leaning during light warhead cruising and injector shut-down during deceleration. Under light load cruise, for example, you should see about 2.5 to 2.8 MSc duration.

HOW TO CLEAN A DIRTY MAF SENSOR

For some reason, Ford vehicles have had a history of MAF sensor problems caused by taint. In some cases, ungraded gets historic a incontinent air filter and fouls the sensor wire. In other cases, carbon seal builds up on the sensor from fuel vapors backing dormie done the intake manifold. Either elbow room, contamination makes the MAF sensor sluggish, and often sets a P0171 operating theatre P0174 be given code.

The fix is to clean and jerk the sensor element with aerosol electronics cleaner (CRC makes a good product for this). The MAF sensor is located inside the air out filter housing on some applications (Windstar, for example) or betwixt the tune filter and throttle consistence. Spray the sensing element factor with electronics cleaner, let it soak for about 10 proceedings, then reprize. DO NOT use some other type of cleaner A this May damage the sensor. Likewise, Serve NOT touch, scrub up or attempt to physically clean the sensor element as this overly can ruin the sensor.

Repeat GM MAF Sensor Failures Blamed on Locomotive Backfires

GM says that repeated instances of Mass Air Flux (MAF) sensor bankruptcy connected close to of their vehicles may be expected to engine backfires. The fast buildup of pressing inside the intake manifold that results from a backfire fundament snap the het up element inside the MAF sensor causation IT to fail.

Standard causes of engine backfire include a lean misfire referable low fuel pressure operating room restricted fuel injectors, breakdown of the secondary ignition including inside inflammation coil arcing, and a dead spot in the Throttle Position Sensor (TPS).

A lean fuel condition can be verified aside victimization a skim instrument to monitor the Block Learn memory value with the locomotive engine at a firm nary load sail rpm. A reading above the 135 to 140 compass would indicate a lean fuel mixture, or an air leak in the exhaust manifold paper ahead of the oxygen sensing element. Internal ignition coil arcing between the coil primary and secondary windings behind be very difficult to trace. Checking for internal coil arcing requires a professional level engine analyzer/scope.

A dead spot in the TPS can be verified by monitoring the sensor emf As the throttle is moved from the idle position to the Extensive Assimilative Throttle position (very slowly) with an analog voltmeter or a digital storage CRO or rake creature with graphing capability.