(Fixed) Weekly waveform 18 - How to test a digital MAF sensor

[@macdonaldsmotorworks]

wicked tip on using the frequency (instead of ac/dc) Chad. Thanks for pointing that out!

[@spelunkerd]

Lots easier to read this version, and even audio is more clear. Thanks for the effort!

[@ThePracticalMechanic]

Glad to hear that! I wouldn't have noticed if you didn't let me know on the last one. Thanks!!

[@roberthemmerly500]

awsome videos you put out some great content thanks for your hard work

[@mike-yp1uk]

I wonder if you remove the mass air flow sensor and regulate some airflow into a known good sensor could you then regulate air to get the same voltage and then determine based on airflow the condition of the MAF sensor? There's an idea that just came to my mind watching this video.

[@ThePracticalMechanic]

That is how they test and calibrate them on the assembly line. The problem with that is knowing what good is. You would have to start testing them and making a database of know good at certain airflows. Many Toyotas use the same part number sensor on engine sizes between 1.5l and 5.7l. They just change the size of the tube the sensor is mounted in. A larger tube lowers the air velocity at the same airflow so the ECM has to be calibrated for that tube size and MAF voltage in order to convert it to grams/second. Many aftermarket cold air intakes mess with the tube size and cause issues with MAF readings. Some will run a larger tube and then narrow the tube near the MAF sensor to attempt to match OEM airflow. A larger tube will cause lean running and a smaller tube will cause rich running unless the ECM is tuned for the change in tube size. This is where the GM MAF sensors are nice because the tube is part of the sensor and a honeycomb is placed at the beginning of the tube to straighten air flow. The sensor calibration isn’t affected by intake tube changes with this style of sensor.

[@gingi801]

So just to be clear, when the car is at KOEO, the sensor IS measuring a frequency? Also what frequency (HZ) should be normal on a chevy when it's KOEO?

[@gingi801]

I was under the impression that there should not be any kind of measurement while the engine is off since there is no volume of air measured across the sensor while the engine is off

[@dangerdavefreestyle]

I have a maf/iat sensor with 6 wires. 2 wires are for the iat. the other 4 are for the maf. of these 4 wires.... one is 12v....one is ground.....one says maf return which the wiring diagram indicates is pcm supplied ground.....one says maf signal. looking at the shape and design it appears i have a hot film type which the whole thing just resembles a small rectangular chip, perhaps the surface area of a half dollar. can i safely assume that the signal it generates is digital and in hertz? i do not have an oscilloscope however my multimeter has a hertz function. i would like to diagnose this properly being i have a p0102 code and the live data feature on my scanner shows 0.00 grams per minute at any rpm (dead)

[@ThePracticalMechanic]

I could still be either design. voltage or frequency based. I would check to see if you have voltage on the wire first. Even if its a digital MAF sensor the Meter will average the reading. if you have some voltage displayed start the car and see if the reading changes, next try the hertz option and see if you get a reading.

[@ThePracticalMechanic]

Also, some vehicle and some scanners will show you MAF voltage or frequency in the data list.