How To Clean Maf Sensor On A 2000 Ford Windstar

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Mass Airflow MAF Sensor

Mass Airflow MAF Sensors

Mass airflow sensors (MAF), which are used on a variety of multiport fuel injection systems, come up in two basic varieties: hot wire and hot moving picture. Though slightly different in design, both types of sensors measure the volume and density of the air entering the engine then the reckoner tin calculate how much fuel is needed to maintain the correct fuel mixture.

Mass airflow sensors take no moving parts. Dissimilar a vane airflow meter that uses a spring-loaded flap, mass airflow sensors utilize electrical current to measure airflow. The sensing element, which is either a platinum wire (hot wire) or nickel foil filigree (hot film), is heated electrically to keep it a certain number of degrees hotter than the incoming air. In the example of hot flick MAFs, the grid is heated to 75 degrees C. higher up incoming ambient air temperature. With the hot wire sensors, the wire is heated to 100 degrees C. to a higher place ambience temperature. As air flows past the sensing element, it cools the chemical element and increases the electric current needed to keep the element hot. Considering the cooling effect varies direct with the temperature, density and humidity of the incoming air, the amount of current needed to keep the element hot is directly proportional to the air "mass" entering the engine.

MASS AIRFLOW SENSOR OUTPUT

MAF sensor output to the computer depends on the type of sensor used. The hot wire version, which Bosch introduced dorsum in '79 on its LH-Jetronic fuel injection systems and is used on a number of multiport systems including GM'southward v.0L and 5.7L Tuned Port Injection (TPI) engines, generates an analog voltage signal that varies from 0 to 5 volts. Output at idle is unremarkably 0.4 to 0.eight volts increasing upwards to 4.5 to v.0 volts at broad open throttle.

The hot film MAFs, which AC Delco introduced in '84 on the Buick turbo V6 and have since used on the two.8, 3.0 and 3.8L V6 engines, produce a square wave variable frequency output. The frequency range varies from 30 to 150 Hz, with 30 Hz being average for idle and 150 Hz for broad open up throttle.

Mass Airflow MAF Sensor digital waveform

Another difference between the hot wire and hot film sensors is that the Bosch hot wire units have a self-cleaning wheel where the platinum wire is heated to 1000 degrees C. for one second after the engine is close down. The momentary surge in electric current is controlled by the onboard estimator through a relay to burn off contaminants that might otherwise foul the wire and interfere with the sensor's ability to read incoming air mass accurately.

MASS AIRFLOW SENSOR DIAGNOSTIC FAULT CODES

An engine with a bad MAF sensor may beginning and stall or exist hard to first, information technology may hesitate under load, idle rough or run excessively rich or lean. The engine may likewise hiccup when the throttle suddenly changes position.

Often, a dirty or faulty MAF sensor volition cause the engine to set a LEAN code and turn on the Check Engine Light. If the MAF sensor wire becomes dirty or is contaminated with oil (from an aftermarket reusable air filter), it will exist dull to react to changes in airflow. This may cause the MAF sensor to under-written report airflow, causing the engine to run lean.

On OBD II vehicles, the input from the MAF sensor is combined with those class the throttle position sensor, MAP sensor and engine speed to calculate engine load. If your browse tool can display calculated engine load, await at the value to encounter if the load is low at idle, and higher when the engine is running nether load. No change in the reading or a reading that makes no sense could bespeak a trouble with any of these sensors.

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

P0100....Mass or Volume Air Menstruum Excursion

P0101....Mass or Volume Air Flow Circuit Range/Operation Problem

P0102....Mass or Volume Air Flow Excursion Depression Input

P0103....Mass or Volume Air Flow Circuit High Input

P0104....Mass or Volume Air Flow Circuit Intermittent

P0171....System too Lean (Banking company 1)

P0172....Organization likewise Rich (Bank 1)

P0173....Fuel Trim Malfunction (Bank ii)

P0174....Organisation likewise Lean (Banking company ii)

P0175....Organisation likewise Rich (Bank 2)

On older Pre-OBD 2 vehicles, you can employ a browse tool or manual flash code procedure to read the codes:

GM Pre-OBD II: Lawmaking 33 (also high frequency) and Code 34 (also low frequency) on engines with multiport fuel injection but, and Code 36 on 5.0L and five.7L engines that use the Bosch hot wire MAF if the burn down-off bike after shut-downwardly fails to occur.

Ford Pre-OBD II: Lawmaking 26 (MAF out of range), Code 56 (MAF output also loftier), Code 66 (MAF output too low), and Code 76 (no MAF change during "goose" exam).

Of class, don't overlook the basics, too such equally engine pinch, vacuum, fuel pressure, ignition, etc., since problems in whatever of these areas can produce similar driveability symptoms.

MASS AIRFLOW SENSOR DIAGNOSIS

Unlike vane airflow meters with their movable flaps, MAFs accept no moving parts so the just way to know if the unit is functioning properly is to await at the sensor'due south output, or its effect on injector timing.

With the Bosch hot wire sensors, sensor voltage output can be read directly with a digital voltmeter by probing the advisable terminals. If the voltage readings are out of range, or if the sensor's voltage output fails to increment when the throttle is opened with the engine running, the sensor is lacking and needs to be replaced. A muddy wire (which may be the effect of a lacking cocky-cleaning circuit or external contamination of the wire) tin make the sensor boring to respond to changes in airflow. A broken or burned out wire would obviously prevent the sensor from working at all. Ability to the MAF sensor is provided through a pair of relays (one for power, ane for the burn-off cleaning cycle), so cheque the relays commencement if the MAF sensor appears to be dead or sluggish.

On GM MAF sensors, there are a couple of quick checks you lot can exercise for vibration-related sensor problems. Attach an analog voltmeter to the appropriate MAF sensor output terminal. With the engine idling, the sensor should be putting out a steady ii.five volts. Tap lightly on the sensor and notation the meter reading. A adept sensor should show no change. If the analog needle jumps and/or the engine momentarily misfires, the sensor is bad and needs to be replaced. You can also check for heat-related issues by heating the sensor with a pilus dryer and repeating the exam.

This same test can likewise exist done using a meter that reads frequency. The older Air conditioning Delco MAF sensors (like a 2.8L V6) should show a steady reading of 30 to 50 Hz at idle and 70 to 75 Hz at 3,500 rpm. The subsequently model units (like those on a 3800 V6) should read about 2.9 kHz at idle and 5.0 kHz at iii,500 rpm. If tapping on the MAF sensor produces a sudden alter in the frequency betoken, information technology'due south time for a new sensor.

On the GM hot film MAFs, you tin also tap into the onboard calculator data stream with a scan tool to read the MAF sensor output in "grams per second" (GPS). The reading might go from 3 to 5 GPS at idle up to 100 to 240 GPS at wide open throttle and 5000 RPM.

The scantool GPS reading at idle will vary by engine displacement. The larger the engine, the higher the GPS reading at idle. The GPS idle reading will roughly correspond to engine displacement in liters. A 3.0L V6 engine, for example, volition generate a GPS reading of about three.0 grams per 2nd at idle. A larger five.0L V8 would read effectually 5 grams per 2nd, and a smaller two.0L four cylinder would read effectually 2 grams per second at idle.

Some vehicle manufacturers publish MAF sensor GPS reading specifications for specific engine speeds. The engine is held steady at the specified RPM to compare the scantool GPS reading to the spec. If the reading is off past more than than 10 percent, the MAF sensor is not reading airflow correctly. The crusade could be a dirty sensor that needs to be cleaned.

Like throttle position sensors, there should be polish linear transition in sensor output throughout the rpm range. If the readings bound all over the place, the estimator won't exist able to deliver the right air/fuel mixture and driveability and emissions will suffer. And so you should also bank check the sensor'southward output at diverse speeds to see that it's output changes appropriately. This tin can be done by graphing its frequency output every 500 rpm, or past observing the sensor'due south waveform on a telescopic. The waveform should be square and show a gradual increment in frequency equally engine speed and load increment. Any skips or sudden jumps or excessive noise in the pattern would tell you lot the sensor needs to be replaced.

Another manner to check MAF sensor output is to run into what effect it is has on injector timing. Using an oscilloscope or multimeter that reads milliseconds, connect the test probe to whatsoever injector ground terminal (1 injector terminal is the supply voltage and the other is the footing excursion to the calculator that controls timing). Then look at the duration of the injector pulses at idle (or while cranking the engine if the engine won't first). Injector timing varies depending on the application, only if the mass airflow sensor is not producing a indicate, injector timing will be about four times longer than normal (possibly making the fuel mixture too rich to offset). You can also utilize millisecond readings to ostend fuel enrichment when the throttle is opened during acceleration, fuel leaning during light load cruising and injector shut-down during deceleration. Under low-cal load cruise, for example, yous should run into about 2.5 to ii.8 Ms elapsing.

HOW TO Make clean A Muddied MAF SENSOR

For some reason, Ford vehicles have had a history of MAF sensor issues caused by contamination. In some cases, dirt gets past a leaky air filter and fouls the sensor wire. In other cases, carbon varnish builds up on the sensor from fuel vapors backing up through the intake manifold. Either way, contamination makes the MAF sensor sluggish, and often sets a P0171 or P0174 lean code.

The fix is to clean the sensor chemical element with aerosol electronics cleaner (CRC makes a good product for this). The MAF sensor is located inside the air filter housing on some applications (Windstar, for example) or between the air filter and throttle body. Spray the sensor element with electronics cleaner, permit it soak for near 10 minutes, so repeat. Practise Not utilise any other type of cleaner as this may damage the sensor. Also, Exercise NOT impact, scrub or attempt to physically make clean the sensor element as this besides can ruin the sensor.

Repeat GM MAF Sensor Failures Blamed on Engine Backfires

GM says that repeated instances of Mass Air Flow (MAF) sensor failure on some of their vehicles may be due to engine backfires. The sudden buildup of pressure within the intake manifold that results from a backfire can crack the heated element inside the MAF sensor causing it to fail.

Common causes of engine backfire include a lean misfire due to depression fuel pressure or restricted fuel injectors, breakup of the secondary ignition including internal ignition curlicue arcing, and a dead spot in the Throttle Position Sensor (TPS).

A lean fuel condition can be verified by using a scan tool to monitor the Block Acquire memory value with the engine at a steady no load cruise rpm. A reading above the 135 to 140 range would bespeak a lean fuel mixture, or an air leak in the frazzle manifold ahead of the oxygen sensor. Internal ignition coil arcing between the coil primary and secondary windings can be very difficult to trace. Checking for internal curl arcing requires a professional level engine analyzer/telescopic.

A expressionless spot in the TPS tin can be verified by monitoring the sensor voltage as the throttle is moved from the idle position to the Wide Open Throttle position (very slowly) with an analog voltmeter or a digital storage oscilloscope or scan tool with graphing adequacy.