New tuner/ maf tune

[gtp_cc]

I am new to tuning. I just logged my first scan. I want to try to do a maf tune, but I am unsure of what all to do. My main problem is trying to get a histogram to work for my maf hz and airflow. Once I have that I just correct the airflow in my pcm by multiplying the cell my half the differnce ie at 17500rpm my scanshows 2.54 but my table in the editor shows 2.40, I would take 2.54/2.40=1.06 then multipy the table in the editor by 1.03 using the 50% rule. Am I right or am I way off? Thanks for helping, oh and my car is a 2001 Grand Prix GTP and my mods are in my sig. Here is my scan and the config I made to see the maf table.

[Andy0x1]

You should never need to calibrate your MAF unless you modified it or its housing.

I ported mine and pulled the sensor out, then installed an LS6 MAF further upstream, I unfortunately don't know what values to use for the new one as looking at stock vehicle BIN's of those that have LS6 MAF's all seem to vary. This MAF also flows over 11500 WOT, so I'm thinking I should probably buy one with a known accurate table.

[Eddie-98GTP]

This MAF also flows over 11500 WOT, so I'm thinking I should probably buy one with a known accurate table.

This has nothing to do with the MAF table, it is a measure of the airflow through the sensor. The table simply converts the frequency (hertz) to a usable value (grams/lbs per second) so the PCM can meter fuel correctly.

If you're outflowing the MAF (hertz over 11500) then you nee to scale back the MAF sensor output, or add a resistor in the MAF sensor itself (like the SLP 85mm sensors have) to reduce the frequency.

Either way, I always start MAF tuning with a stock MAF table, regardless of which MAF sensor the car has installed. It doesn't matter where you start, you will end up at the same place if you do it right anyway.

[gtp_cc]

I guess I am confused as to which table to be modifying to get my fuel trims in check. I know the VE table is used for when the maf fails, but I want to get them tuned for my normal driving. So I guess my question is what table I need to modify? THanks

[Eddie-98GTP]

Engine -> Airflow -> General Airflow -> MAF Calibration -> Airflow vs Frequency

[Andy0x1]

This has nothing to do with the MAF table, it is a measure of the airflow through the sensor. The table simply converts the frequency (hertz) to a usable value (grams/lbs per second) so the PCM can meter fuel correctly.

Isn't that what I said? (hence my interest in a different MAF that doesn't report such a high Hz for a given volume of airflow)

If you're outflowing the MAF (hertz over 11500) then you nee to scale back the MAF sensor output, or add a resistor in the MAF sensor itself (like the SLP 85mm sensors have) to reduce the frequency.

The output is PWM, I'm not sure a resistor is going to help much, something like a MiniAFC would be needed. (or different MAF)

Either way, I always start MAF tuning with a stock MAF table, regardless of which MAF sensor the car has installed. It doesn't matter where you start, you will end up at the same place if you do it right anyway.

I suppose - I would think; even if you did use your MAF to tune using the Open loop MAF error % method, once you established an accurate tune, it would be interesting in some way to use the differences to tune the VE table, and revert your MAF back to the stock (accurate) values with the end result being both a good tune, and an accurate MAF, rather then an inaccurate MAF that corrects for other innacurate variables. (if that makes sense)

[Eddie-98GTP]

Isn't that what I said? (hence my interest in a different MAF that doesn't report such a high Hz for a given volume of airflow)

Kind of...

This MAF also flows over 11500 WOT, so I'm thinking I should probably buy one with a known accurate table.

I was simply saying the table has nothing to do with MAF sensor output

The MAF sensor outputs a frequency, but the duty cycle (pulse width) is not changed. I know what you're saying, but technically it's not a PWM sensor (PWM is actually used on controlled circuits anyway). The resistor I was was referring to would not be placed in the signal line, but rather on the sensor itself between the 2 contacts of the hotwire. This would decrease the resitance of the circuit fooling the MAF circuitry in to thinking there's not as much air coming through the sensor. This would cause a decrease in the frequency of the output signal. SLP scaled their MAF sensors in this way. There was write up on ClubGP or the PT forum a few years back.

I suppose - I would think; even if you did use your MAF to tune using the Open loop MAF error % method, once you established an accurate tune, it would be interesting in some way to use the differences to tune the VE table, and revert your MAF back to the stock (accurate) values with the end result being both a good tune, and an accurate MAF, rather then an inaccurate MAF that corrects for other innacurate variables. (if that makes sense)

This would be a great idea, if the VE table were actually used enough to skew the trims that much. I have been dissassembling my PCM in my spare time over the past couple months, and have not been able to find in the code where the PCM uses the VE table for general fuel calculations. Transient fuel sure, MAF failure fuel definatly, but I haven't seen where it really makes troo much different with the MAF sensor working. I tried running a zero'd VE table for a couple days about a year ago, and didn't notice any change in the way the car ran (except for coming to a stop a little), and no change at all in fuel trims. I have since reverted back to a tuned VE table just in case the MAF sensor took a dump.