Freshmac

I'm trying to diagnose my maf sensor. I conducted a test w/a DMM and the voltage was 1.96 I then tried to conduct a throttle body test by increasing the RPMs to see how it reacted, the voltage declined instead of inclining as most videos online suggested that it should. There was no slowness to react it didn't fluctuate up and down it just decreased. What does this tell me about my maf sensor and the reading that I obtained. Thanks for your time

chem_man

Measuring the voltage across/to/through the MAF with a DMM is meaningless. You need a live data scanner to read what the ECM is seeing in terms of data from the MAF with respect to the reference voltage/signal the ECM sends to the MAF.

The live data scanner will then show you the amount of air going through the MAF sensor in terms of grams/second or the equivalent in English units. The MAF consists of a heated wire or wires and by the current required to keep the temperature of those wires constant as the air moving past them cools it/them, the ECM translates the current draw into mass of air flowing through the sensor and adjusts the fuel rate and the throttle body butterfly valve accordingly in order to meed engine demand.

So, in order to diagnose whether or not the MAF is functioning properly, you need the right tool to do so an a DMM is not the correct tool. Something like this:


paired with the Torque Pro app from the Google play store (provided you have an android device) is what you need.

Good Luck!

tech2

what he said.
typically, with a warm engine at low idle...the maf should read approx the same grams/second as the engine displacement..ie 5.7l engine reads approx 5.7g/second.

if your fuel trims are within +/- 10 % and you have no maf codes...the maf is probably good. What kills mafs are bad quality air filter and heavily oiled wet air filters.
post the codes you are getting, symptoms, model year and engine if you want help.

06blusilvy

Agreed with others, live data scan is the way to go for diagnosing maf issues. For example my 06 1500 5.3 was giving me long term fuel trims at around 20-23 at idle and operating temp. The Maf was reading .5 lb per min with no codes but noticeable performance and rich running issues. The Maf should be at .75 lb per min at idle which converts to 5.5ish g/s, I have an older scanner.
Your maf should be at or slightly more G/S as it correlates to engine size in liters. I have a 5.3 so 5.5g/s is acceptable at idle. Cleaned maf and the readings went up but not high enough. Ultimately replaced maf and truck is not longer rich with rough idle and fuel trim is back to 3 or less in long term.
Get a good scanner that reads live data, watch your fuel trims, LT and ST should balance each other close to zero at idle. Clean MAF first, then recheck. G/s readings should be at or slightly above engine displacements.
it's not exact science but this process has worked for me with rich / lean issues on these trucks.
Learning about fuel trims tell you alot about what is going on