Can someone help explain the way the newer Mustang MAF operates. i understand the old way of airflow and voltage but I can not figure out the new stuff, I think I need an analog to put it into perspective.
Can someone help explain the way the newer Mustang MAF operates. i understand the old way of airflow and voltage but I can not figure out the new stuff, I think I need an analog to put it into perspective.
The units are "Period" witch is another way to represent frequency. Essentially as air mass increases, period values decrease. It tunes just like any other MAF table, you just need to be logging and plotting the correct values.
Jaime
What is the correlation between period and the frequency? What is the time period?
Finally something I know about.
Period is frequency basically. You log it same as with voltage & apply corrections the same way. Higher numbers are lower airflow on the period scale, if you make the numbers larger in the airflow column, it'll richen the motor up, at that period.
Thanks for the replies. I want to learn this stuff for sure! Based on a conversation I had with a powertrain engineer, the MAF doesn't need to be calibrated or adjusted if the transfer function was created in an airflow lab. I'm just trying to understand what the table is showing me. I was confused by the terminology and the fact that it was descending based on airflow.
So is there a way to figure out what time period equals what frequency
The table is 2d, and the period is the rows, and the one column is airflow. You need not worry about what freq equals what period, simply tune the MAF with HPTuners, and the A/F is correct. I think your engineer is correct, but in the real world, this is how the fuel is tuned on these, or the main part, anyway.
To answer your question, a period is a measure of time, and in pcm's it's measured in microseconds, you can Google a microsecond to period converter, if needed
In a perfect lab situation with a fixed diameter of straight pipe, or if running the exact configuration it was calibrated with in the lab, he is correct. However in the real world of air intakes, twists/turns, larger diameter tubes, sensor positioning, and even air filter design can effect the airflow distribution around the sensor element and will change the air mass/period relationship.Originally Posted by C_Murph12
Slap a JLT CAI on a completely stock Coyote and you will see a table shift of over 20%. Possibly more, I can't remember right now.
Jaime
To put it another way, If you make a bunch of modifications to the engine, camshaft, heads, exhaust, but run the stock air box and piping configuration. Your MAF transfer will not change and fueling should still be correct.
Jaime
An analog MAF is just 0-5 volts. You say you know how they work. There's a positive and negative direct current. More voltage is needed to maintain the hot wire tempature with more airflow.
Digital MAF is frequency based. That is the positive and negative are constantly alternating.
Period is the time between polarity changes. Frequency is how many polarity changes during a given time. More alternating is needed to maintain the hot wire tempature with more air.
The housing size the MAF is in determines the relationship between airflow and wire tempature. You correct the airflow values the same with either type of MAF.
So higher numbers are higher flow and the table is upside down? I think that's what confused me.
No.
Why does the table start high?
Period is the reciprocal of frequency (1/Hz); the amount of time one cycle takes.
ex. 20 Hz has a period of 0.05 (1/20)
Some times a visual helps. Shorter period(smaller numbers) is higher frequency, longer period(larger numbers) is lower frequency. More airflow = higher frequency needed to keep hot wire at set temperature.
frequency-and-wavelength.png
Last edited by murfie; 03-29-2018 at 02:11 AM.
in case you have boosted app (e.g 2011 coyote with 650whp) and u are facing lean scenario at top RPM and according to maf table you have only top 2-3 cell to adjust short trim and even after adjust these cell you still have lean . is it ok to re scale the period to have enough frequency or swap to after market MAF. and what is the maximum power the stock maf can handle )
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