MAF values

[wamboin23]

Hey All,

Just reading some other post relating to MAF values etc, and people have mentioned adjusting the values to suit mods, including intakes, exhausts etc.

How do mods like this affect the frequency of the MAF, when it just reads airflow and outputs a frequency? Or is it another table of values that get put out?

Cheers,
Brendan

[The1]

use the excel file yoda made here to convert your changes back to hex for input into tables in tunerprohttps://pcmhacking.net/forums/view ... f=28&t=659

[wamboin23]

i've got that much, but why do they need adjusting to start with. doesn't the MAF just tell the ECU theres more airflow? Or is there more to it than that?

And how do you know what to change them to? Measure the airflow with something seperate from the vehicle?

[Jayme]

the values only need changing to suit either a bored out maf or a maf off a different engine. any other mods to the engine wont matter as long as the maf itself is physically the same, then it will still meter the correct amount of air and adjust fuel to suit.

if you have changed the maf and need to change the values you just use a wideband oxygen sensor and adjust the MAF tables till the commanded AF ratio matches the actual AF ratio.

[The1]

i only use MAF scalers to adjust fuel trims back to within 2% as there isn't any adjustment yet for injector rates.

In the end the outcome is the same for me, just the G/S airflow wont actually be right.

[wamboin23]

i only use MAF scalers to adjust fuel trims back to within 2% as there isn't any adjustment yet for injector rates.

In the end the outcome is the same for me, just the G/S airflow wont actually be right.

ok, i think this is where i was getting confused. I was under the impression that you were adjusting the MAF values because of a change in airflow, which is why I couldn't work it out.

Thanks all for the help.

[The1]

yeh i see where your coming from, it is because of a change in airflow, either exhaust or intake mods or forms of induction, but modifying it for the reason above.

[yoda69]

Biggest thing that affects the MAF is anything that changes the air pattern over it.
Some common ones are retrofitting engine to a different vehicle and relocating MAF, if MAF is directly after a bend the flow across the resistors can be different.
The same sort of thing happens with POD filters depending where they are placed relative to the MAF.
Descreening the MAF can also change flow rates.
Cold air intake using the factory airbox should cause little problems, as the airflow between filter and MAF hasn't changed.
Different (especially large) cams can cause a problem, as the air pulses over the MAF sensor and gets counted twice, once on the way in, and again on the way out, same thing can happen with later model vehicles fitted with an intake resonator if it is removed.

In general, a MAF based tune will cope with engine hardware changes much better than MAP, but there is always room for improvement with fine tuning.

yoda69