MAFT Tuning/ Tuning in General (How to log / read Vf Hz)

[suprra_girl]

found this cached in google... thought i mite bring it back

i've just needed to find this info for someone so someone else may also find it useful again

Original post by Serzy

I just got my MAFT installed and I have regular Autometer EGT & O2 guages and a Digital Voltmeter that can display Hz now I have a few questions and I hope some of you gurus out there can answer for me

My voltmeter can display Hz it has two settings for displaying it High Trig. & Low Trig. whats the difference between the two? Which one would I use to monitor my Vf signals Hz? To monitor the Vf signals Hz with my voltmeter I use the Diagnostic Blocks Vf port for the red probe of my voltmeter and the E1 port for the black probe of the voltmeter... Is that correct?

Now in the MAFT it has options for a 1500hz clamp a 1450hz clamp and an 1400hz clamp? Which one is the safest to run? Or which one will allow me to hit FC sooner? I just want to run like 15psi my stock fuelcut occurs around 13.5 to 14.5psi.

At the moment in the base settings for my MAFT I have
Aux C (1400hz clamp)
Base 2
Idle 0
Mid 1
WOT F

With these settings my autometer AF is always bouncing into the green for cruise and part throttle and when WOT the gues lights up to the third green (I know the narrowband isnt accurate but it shows that im not goin lean) my EGT'S are actually a bit lower than stock and the cars throttle seems much more peppy and boost seems to give more of a snap on effect.


Thanks for any help or insight anyone can provide. And if anyone wants to chime in with any offtopic but relevant information please do!

 

[suprra_girl]

reply by Shawndude

Serzy wrote:
My voltmeter can display Hz it has two settings for displaying it High Trig. & Low Trig. whats the difference between the two? Which one would I use to monitor my Vf signals Hz? To monitor the Vf signals Hz with my voltmeter I use the Diagnostic Blocks Vf port for the red probe of my voltmeter and the E1 port for the black probe of the voltmeter... Is that correct?

The Vf is a simple voltage output from zero to 5 volts. You do not need to use the frequency Hz function of the meter. You have it connected correctly, just set the meter to a DC voltage range of about 20 Volts. I'm assuming you know how to use the Vf information, if not we can go over it.

Now in the MAFT it has options for a 1500hz clamp a 1450hz clamp and an 1400hz clamp? Which one is the safest to run? Or which one will allow me to hit FC sooner? I just want to run like 15psi my stock fuelcut occurs around 13.5 to 14.5psi.

None of them are really safer than others, as they are ment to elliminate fuel cut entirely. I would suggest NOT using the FCD without a wide band A/F meter. You can lean out the upper flow portion of the MAFT to get the slightly higher boost level you want and still keep the fuel cut to save the day, if need be.

The different ranges were provided as people experience fuel cut at different Hz. The idea is to start clamping it as high as you can go. Once again, without a wide-band I would not use the FCD feature.

At the moment in the base settings for my MAFT I have
Aux C (1400hz clamp)
Base 2
Idle 0
Mid 1
WOT F

Looks like you're already leaning out the WOT a little. I would turn off the FCD (Aux = 0). Then I would get the Vf readings adjusted to stock levels, and finally lean out the WOT a little to get the higher boost you're after.

 

[suprra_girl]

Serzy writes:

For driving light throttle it says to set it to vf of 2.5 volts. At light throttle the best I can get is 2.23 volts than if I give it a bit more throttle it goes to like 3.5 and a little less and around 1.35 volts... 2.23 is with base 0 and aux 0

The directions for the maft are mediocre at best they could use some more details as far as whats considered what, things are quite vague.

 

[suprra_girl]

chevyeater writes:

Some Supras will put out 2.25 volts instead of 2.5. 2.23 volts means your contacts might be a little dirty

 

[suprra_girl]

Shawndude writes:

Don't worry about the decimal points in the voltage. That's why I suggested a 20 Volt scale, so it gets rid of the decimal places on your meter display. There are only 5 steps in the Voltage output, the decimal points do not mean anything and will bounce around due to wire resistance, heat, alternator output etc.

Set the multimeter so it only shows one decimal point, for example 2.5V.

During normal driving (oxygen sensor feedback) you want the output to be usually in the 2.5 Volt range (approximate voltage). Changing to 1.75 volts and 3.75 volts under various driving is perfectly normal. Only when you get to 0 volts and 5 volts on a constant basis you need to retune it. Set it while on the highway at about 60 mph to be 2.5Volts. You will find that you can adjust the MAFT a little and the Vf will stay in the same spot, but it will jump to a different level sooner under changing conditions. So if you find that it jumps to 3.75Volts frequently, you can lean out the MAFT a little and it will be more constant at the normal 2.5 Volt level.


I'll quote myself from previous post.

The Vf output can tell you how far it's adjusting things from the base maps. It has 5 outputs:

5 volts = adding lots of fuel from base maps
3.75 volts = adding little bit of fuel from base maps
2.5 volts = no change from base maps
1.75 volts = reducing some fuel from base maps
0 volts = reducing lots of fuel from base maps

The Vf will go to 0 volts when decelerating, and when accelerating and going into open loop (richer than 14.7 A/F). Ignore the Vf output at idle.

 

[suprra_girl]

serzy writes:

Thank you very much you just cleared up my mind! Ive tried searching for that kind of blurb you just posted for days now. (It sucks cause you cant search for anything less than 3 characters which makes searching for anything about Vf very hard )

Also on my voltmeter in the 20volt scale it reads the 2.23 and 200volt scale will read with 2.5... ?? Ill have to go take another stab at this. I am reading way to far into these instructions

THANK YOU!!


And chevyeater which contacts are you refering to being dirty? I always try to make sure things have good connections...