The egr temp sensor is connected to the thg terminal on the ecm. Dtc p0102 mass air flow maf sensor circuit low frequency. You can get another maf for a small amount of money, but the maf you need is a pierburg and the maf you can get is a bosch. Now that you have a broad knowledge of how an airflow meter works, you are ready to test the maf sensor. This test will help you check the condition of this wire. How to test a mass air flow maf sensor without a wiring diagram. From the increase in temperature, the ecm knows the egr valve is open and that exhaust gases are flowing. Its always a good idea to test a mass airflow maf sensor before replacing it. We carry great brands like acdelco, bosch, duralast, hitachi, and more. Dtc p0102 mass air flow maf sensor circuit low frequency circuit description the mass air flow maf sensor measures the amount of air which passes through the sensor into the engine during a given time. Bosch hfm6 digital air flow meters can be reliably tested with still air conditions, ignition on, engine off and exhaust extraction systems removed. In this tutorial, im gonna show you how to do it with just a multimeter and in stepbystep manner. According to this, the maf sensor signal wire is the one labelled as number 3.
Mass air flow converters on a rainy monday, when youre late for work, suddenly your tdi looses power. The main function of the mass air flow maf sensor is to measure the volume of air passing through it, and therefore into the combustion chamber of the engine. So either the maf sensor on my truck may be faulty, or it is supposed to be tested in a different way. If for example you have intake air leak the maf no longer measures all air getting into the engine and lh doesnt add fuel to make a correct mixture. Cam sensor ckp crank sensor cmp air flow sensors ammmaf engine coolant sensor ect throttle position switch tps heated oxygen sensors hego accelerator position app map sensor map knock sensor ks. Automotive sensor testing diagnostic strategies of modern automotive systems book 1 kindle edition by concepcion, mandy. Cam sensor ckp crank sensor cmp air flow sensors ammmaf engine coolant sensor ect throttle position switch tps heated oxygen sensors hego accelerator position app map sensor map knock sensor ks exhaust gas temperature fuel temperature sensor egr position sensor inputs ignition coils idle speed control valve iscv.
Before we jump into the diagnostic, lets take a look at how the maf sensor works so the procedure makes sense to you. Check the vacuum hose attached to the sensor and make sure it is in good condition and free of obstructions. Jan 17, 2019 some vehicles come equipped with both a map and maf sensor, usually forced induction systems like turbocharged and supercharged models. Jul 20, 2009 a maf sensor can be tested without a scan tool. Basically, the maf sensor measures the amount of air flowing into the engine through the air cleaner assembly, which contains the air filter and connects to the throttle body. The air flow sensor maf is located in the intake air stream and measures the mass of air entering the engine. If you have a mass airflow sensor with pulse output, connect the emulator to start the engine and. But the real key to testing with a multimeter is the signal return lead. Symptoms of a bad or failing mass airflow sensor common signs of problems with a mass airflow sensor include running rich at idle or lean under load, decrease in fuel efficiency, and rough idles. Take your vehicle to a professional auto electrical shop for further testing. This months column started on a simple assumptionthat egr flow could be easily calculated by opening the valve at a constant throttle opening using a bidirectional scanner command, vacuum pump, etc. Chapter 12 mass airflow sensor testing scannerdanner. Here is a fast and accurate way to track a mafs performance and output to the pcm. A mass air flow maf sensor responds to the amount of air flowing through a chamber containing the sensor.
Some vehicles use a mass air flow sensor maf instead of a map sensor. Testing of the ho2s this way assures that the catalytic converter will remain efficient. Here is a video on how a mass air flow and a manifold absolute pressure sensor work and also how you can test them using a basic multimeter. In addition to testing and calibration, another important factor for performance is the use of highquality rtd sensors. How to test a mass air flow maf sensor without a wiring. There are few types of air flow sensors, however, modern cars use a hotwire type. Under these conditions the signal frequency must be between 1.
Maf sensor testing the techassist team its always a good idea to test a mass airflow maf sensor before replacing it. Mass air flow maf sensors the mass air flow sensors converts the amount of air drawn into the engine into a voltage signal. Once in a while we may encounter a total failure of a maf sensor, one that is, perhaps, short circuited or internally open. Under these conditions the signal frequency must be. In this article i am going to briefly explain the three basic multimeter tests that are done to find out if its bad or not. The sensor connects to the intake manifold with a rubber hose, depending on your particular application. Jul 24, 2016 here is a video on how a mass air flow and a manifold absolute pressure sensor work and also how you can test them using a basic multimeter. If you test the other leads associated with the maf and you see another 5v reference and a return voltage those will be for the intake air temp. How to test a ford mass air flow sensor it still runs. To find out if this tutorial applies to you specific vehicle, take a.
Jul 25, 20 testing to see if the mass air flow maf sensor on your toyota 1. In this paper an experimental setup was designed and realized in laboratory to test and measure the engine mass air flow sensor used in engine applications. Chec the output of the maf sensor while doing a full throttle run in 2nd gear, as shown in figure b. Yes, a digital multimeter can be used in testing the mass air flow maf sensor. How to test a maf or map sensor with a multimeter plus. A mass airflow maf sensor in a modern ford vehicle is located inside the air intake duct. Is there anything else i can do to see if this really is the problem.
The ecm needs to know intake air volume to calculate engine load. Maf sensors fitting and diagnosis issues professional. Trouble codes p0171 system too lean bank 1 and p0174 system too lean bank 2 are also often caused by a bad or contaminated mass air flow sensor. If you need information regarding your vehicle, consult the repair manual for your particular make and model. When the catalytic converter is working properly the computer sees. Pdf mass air flow and temperature sensors testing by scan. Obdii is a system that was mandated by the federal epa and was developed by the society of automotive engineers sae. The pcm uses the maf information in order to monitor the engine operating conditions for fuel delivery calculations. The photos below compare the stock afm installed on an e30 m3 on the left with the maf 4. The electronic circuit component measures this change in temperature and converts it to a voltage or frequency signal. Without appropriate testing, its hard to distinguishjust by drivingamong certain ignition or knock sensor faults and maf sensor malfunctions. Nov 09, 2017 according to this, the maf sensor signal wire is the one labelled as number 3. Delphi af10043 mass air flow sensor shown delphi quality. First, open the hood of your vehicle and locate the maf sensor on the air cleaner assembly.
How to test a maf or map sensor with a multimeter plus an. Page 45 mass air flow maf sensor test procedure testing is done onvehicle. Pdf in this paper an experimental setup was designed and realized in laboratory to test and measure the engine mass air flow sensor used in. Notice all of the chips,resistors,and capacitors that are used in this computer. Pdf the experiment work to know locations of mass air flow sensor maf and intake air temperatureiat sensors, and classify its types. The data from the maf sensor is simply a voltage between 0v and 5. In addition, to measure inputs and outputs voltage according to the instructions from the above link some modifications of maf s connector are necessary, but i hate to do it. Computers and sensors operation,diagnosis, and service. This measurement allows the ecu to perform adjustments which ensure that the engine is performing to an optimum level. Chapters 4 and 5 fuel trim and oxygen sensor testing chapter 6 temperature sensor, thermistor circuit tests chapter 7 potentiometerposition sensor tests tps, evp, app, vaf etc chapter 8 pressure sensor testing, map, baro, dpfe, fuel tank and rail pressure sensors. Computers and sensorsoperation,diagnosis,and service 593 figure 253 many electronic components are used to construct a typical vehicle computer.
Inputs sensors the egr temperature sensor is located in the egr passage and measures the temperature of the exhaust gases. On most current vwaudi engines, the actual maf value can be found in group 002, field 4 or group 003, field 2. This will be easy to spot because the return voltage will be less than 5v or better be. The chassis wire is the next wire which is black wire with white stripe. Part 1 the basics of testing a mass air flow maf sensor. Maf sensor while doing a full throttle run in 2nd gear, as shown in figure b. Delphi has the high quality emissions, ignition and sensor parts to help you keep that pesky check engine light off and keep your customers happy. It appears that the grams per second is not going above 50, even when the engine is revving at 7000 rpm. Cam sensor ckp crank sensor cmp air flow sensors amm maf engine coolant sensor ect throttle position switch tps heated oxygen sensors hego accelerator position app map sensor map knock sensor ks exhaust gas temperature fuel temperature sensor egr position sensor inputs ignition coils idle speed control valve iscv. In modern cars, an intake air temperature or iat sensor is built in the mass air flow sensor.
How to troubleshoot a mass airflow sensor axleaddict. Additionally, since maf sensors are somewhat pricey, many technicians are afraid to condemn them, fearing either the customers or the boss wrath if their diagnosis is not borne out. Determine what type of map sensor is installed in your vehiclevoltage or frequency type. Mechanics measure the amount of air flow mass air flow sensor readings. Driveability corner egr system maf map motor magazine. Obdii stands for on board diagnostics second generation superseding that of obd1. I actually do not know which pin on maf or on its connector is which, so i can not reliably measure voltage. The element is cooled as air passes over it, and this information is converted into an electronic pulse to be relayed to the onboard computer. If the maf is bad either because its not producing a signal or producing an erratic one, the cars idle will return to normal and the car will seem to run fine. Part 1 vw mass air flow maf sensor test 5 wire type. This is necessary to determine how much fuel to inject, when to ignite the cylinder, and when to shift the transmission.
A completely failed maf sensor will not send any airflow information to the pcm. Autozone carries hundreds of thousands of parts and accessories. Although im not going to be going into details about each of the. The sensor for volume consumption of air is used in many systems for management of engines for measuring value of the transitory cost of air. If the circuit has an issue, replacing the sensor will not solve your problem. Attach the voltmeter or tachometer negative probe to the ground black wire and the positive probe to the signal wire. Chapter 7 potentiometerposition sensor tests tps, evp, app, vaf etc chapter 8 pressure sensor testing, map, baro, dpfe, fuel tank and rail pressure sensors chapters 9, 10 and 11 the 5v reference and signal circuit quick tests chapter 12 mass airflow sensor testing chapters 14, 15,16 fuel delivery and fuel pressure testing chapters. The most common way to test the 5 wire vw mass air flow maf sensor is just to unplug it with the engine running. Explain in detail the testing procedure of a maf sensor. Select your year, make, model and engine to find those that fit your vehicle.
A bad mass air flow sensor is often the likely culprit if your car isnt running as it should. If the maf is not reading correctly the lh module would adapt and correct the mixture based on o2 sensor reading. This type of maf sensor also has an intake air temperature iat sensor as part of the housing assembly. When the oe fails, trust standard comprehensive maf sensor coverage premium quality. Put a stop to engine hiccups and stabilize your engines airfuel mixture with a new mass air flow sensor maf from autozone. A maf sensor that behaves like this will require replacement. Sometimes, a maf sensor s hot wire breaks or gets damaged. Assuming this test is done at or near sealevel, the peak output of the sensor in gs should be roughly 80% of the rated horsepower of the engine.
The symptoms of a bad mass air flow sensor include low engine power, poor fuel economy, an engine that wont start, a check engine light on the dash and a gas smell from the exhaust fumes. In modern cars, the only way to test the mass air flow sensor is with a scan tool. I also show you how you can figure out the wires without a wiring diagram. What type of voltage signal is produced by a vaf and what would you expect to. Pdf experimental stand to evaluate engine mass air flow maf. A hands on presentation of how to test and measure maf sensor readings. But, if youre like me, you want a more solid test, something that. This should be the chassis ground for your mass air flow meter, if you have power and ground here, you can move onto the next section of our how to test a mustang maf guide. The job of the mass air flow sensor is to keep track of the. Make sure there are no loose wires and the sensors electrical connector is in good shape.
I think i will not play anymore with testing and cleaning. If the specified value is obtained but dtc memory has a dtc concerning mass air flow maf sensor, check the voltage supply of. When testing a map sensor, first make a preliminary check. Before replacing the sensor, however, the rest of the circuit should be checked for proper operation. In addition to the larger diameter of the maf sensor you can see the much larger diameter of the elbow connecting the maf sensor outlet to the plenum. I also show you how you can figure out the wires without a. Testing to see if the mass air flow maf sensor on your toyota 1. It uses a hot wire element to measure the amount of air entering the engine. Assuming this test is done at or near sealevel, the peak output of the sensor in. The sensor element and air flow meter body form a calibrated unit and are not interchangeable. Pdf experimental stand to evaluate engine mass air flow. Connect a scan tool to see the maf sensor parameter identification data pid information.
It is intended to be insensitive to the density of the air. Mar 22, 2010 the most common way to test the 5 wire vw mass air flow maf sensor is just to unplug it with the engine running. Much more common, however, are failure modes in which the maf sensor has become unreliable, underreporting or overreporting the true airflow into the engine. Remember you will be testing the harness side of the maf connector. Emulator maf and oxygen sensor sk04a v5 user guide sdsauto. A maf sensor that continuously overreports or underreports airflow into the engine will cause an engine to run rich or lean. A hotwire mass air flow sensor has a small electrically heated wire hot wire. Use features like bookmarks, note taking and highlighting while reading automotive sensor testing diagnostic strategies of modern automotive systems book 1. The hot wire component of the maf cools when air mass flows past. In my case the third wire of the sensor gives a constant 12. Sometimes, the map sensor is used to monitor egr operation, and doubles as a back up to the maf sensor. In reality, egr flow is nothing more than a vacuum leak downstream from the maf sensor.
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