Getting the most out of your Apexi S-AFC= Stock MAF honeycomb removal

[John Monnin]

Innovator discovered something interesting
We should try to keep this thread on track.

He discovered that gutting the MAS let it see less air, so he had to use less his SAFC for less correction and his timing did not advance as far.

The problem is: To get the correct amount of fuel at a particular amount of air flow and RPM, the karmon frequency the ECU sees MUST to be the same. If the Karmon frequency is different the ECU will tell the injectors to supply a different amount of fuel

This can be done several ways but we will only compare 2.
1. Leave MAS alone and use SAFC to add more correction to lower the karmnon frequency.
2. Gut the MAS sensor to lower the karmon frequency a little then use the SAFC to correct tit he rest of the way.

THEORECTICALLY THE TIMING SHOULD BE THE SAME BECAUSE THE ECU MUST SEE THE SAME FREQUENCY.

The bold statement above is what is being debated. Let’s look at this scientifically, examine the validity of the data and examine the assumptions used to make this statement.

1. A statistically significant sample is needed to eliminate random variables that could mess up a test. Maybe Innovators ECU has a Glitch. Maybe he had an intake leak that was fixed when he gutted his MAS. To eliminate these possibilities we need a few more people to do this mod and data log timing before and afterwards. A statistics student will tell you 8 samples are a minimum and 30 samples are best to have significant data.
WHO ELSE HAS GUTTED MAS AND DATLOGGED BEFORE AND AFTER? ON THE SAME DAY AT TEH SAME TEMPERATURE, ELEVATION, GAS and DRIVING STYLE?

2. The statement is based on the ASSUMPTION that only factor adjusting timing is the MAS signal. The MAS sensor measures 3 things, Airflow, Temperature & barmetric pressure.
- What does SAFC do to air temperature readings? The ARC2 replaces the readings with constant values. Does the SAFC modify it at all?
- Does gutting the MAS affect the temperature it sees? Maybe since the less air is flowing across the sensor less heat is loss by convection so the MAS thinks the air is Hotter?
- What effect does gutting the MAS have on the barometric pressure? If the barometric pressure is lower the cars thinks its at higher altitude and will deliver less fuel to compensate for lower denisity air.
- This also brings up the question what happens when the MAS is used as a blow through design (some translater guys are trying this) if these values are that sensistive?

3. Does the elimination of the restriction affect anything?
Turbos do a much better job of pushing air than they do of pulling it.
- If the turbos do not have to work as hard because of gutted MAS maybe the intake charge is cooler?
- I think the ECU advances timing when air is cooler so that is probably not true.
- If the intake charge is cooler, it is denser so less fuel is needed for same volume of air.


The Vendor technical meeting at the national gathering was very interesting. GT-PRO has done a lot or work at trying to modify out stock ECUS. Brian Fuentes commented several times the 3S ECU is very complicated and hard to modify. I am in over my head and guessing on the rest of this thread so feel free to correct my ignorance, the impression I got from this meeting suggested the following:

The Supra ECU is easier to modify because fuel and timing adjustment tables are in on location, fuel/timing can be adjusted in one location, it looks like Toyota planned to make their ECU easy to modify.
The 3S fuel tables are all over the place, you have to find every place the ECU tweaks the fuel/timing tables to keep from messing up. It was obviously not designed to be modified.
The Reason I talk about the ECU is because what innovator is doing with his mod is changing the system just enough that the ECU jumps to a completely different fuel/timing curve.


Again just Guessing, but what I would really like to see is other daring people data log before and after gutting MAS to see if Innovators discovery is repeatable.

[Bluv69k]

WOW, My car is a beast

Took the honeycombs out. They have glue on them so don't try to just tap them. I adjusted my S-afc II. The best part is I saved my old settings in data1 file so I just have to turn a knob to go back. put new settings in data 2. I have stage 3 heads and was running 1.08 bar with .94-.96 o2's at 70% IDC. Man this thing almost took my hair off it was so fast. Knock counts never over 1 except for some phantom knock during shifts.

My rough settings are
low 35%
hi 70%

low
ne 800 +15
the rest is -22

Hi
pretty much is -20 across the board

question, should idle on hi settings be in the +

[John Monnin]

Originally posted by Bluv69k
WOW, My car is a beast

Took the honeycombs out. They have glue on them so don't try to just tap them. I adjusted my S-afc II. The best part is I saved my old settings in data1 file so I just have to turn a knob to go back. put new settings in data 2. I have stage 3 heads and was running 1.08 bar with .94-.96 o2's at 70% IDC. Man this thing almost took my hair off it was so fast. Knock counts never over 1 except for some phantom knock during shifts.

My rough settings are
low 35%
hi 70%

low
ne 800 +15
the rest is -22

Hi
pretty much is -20 across the board

question, should idle on hi settings be in the +

Do you have a datalog showing what effect this had on timing?

P.S. I saw you did a 4-bolt main conversion. Email me your real name and I will add you to my 4-bolt main conversion club list,
" Being a member of the 4-bolt main conversion club is something to be proud of, I know I am. Unfortunately its a club that you would rather not be asked to join"

http://johnmonnin.netfirms.com/ConversionClub.html

[Bluv69k]

I do but I don't know how to post it.
it's about 18 degrees at 98% throttle position
Brian Williams

[BlackStealth]

John, I can answer some of your questions. Unlike the MAFT & ARC2 the Apexi SAFC doesn't modify temperature or barometric values... only Karman (airflow). So those two parameters won't be much of a factor in your quest.

My new MAFT + LS6 MAF has elminated a problem that no one has been able to find a solution to. Adding either v1 or v2 of the Apexi SAFC my datalogger reported a dip in air flow during a steady state throttle input. This dip in airflow would cause the car jerk. Nice side effect, and appears to be reported by myself and one other. I was considering borrowing another MAF to see if that would cure it. Well, it looks like I was on the right track. A new MAF (LS6) cured it. My guess is my OEM MAF may have some sort of impedance mismatch when mated to the SAFC.

I think I'm gonna try the OEM MAF with the honeycombs removed trick. I know my little quirk will reappear, but if this mod is really amazing I'll be hunting for a new OEM MAF.

[ukyo]

Originally posted by John Monnin
Innovator discovered something interesting
We should try to keep this thread on track.

He discovered that gutting the MAS let it see less air, so he had to use less his SAFC for less correction and his timing did not advance as far.

The only thing Innovator has brought to the table that is new on this mod is the dyno reports and the theory on timing. This mod has been done numerous times by numerous 3/S onwers. Notable examples of owners that have shown the amazing benefits of this mod when tuned correctly being Phalse and Racer_X.

What I don't get is why now so many people are listening all of a sudden? Phalse told us about this years ago, and had 11 second time slips on one 9b and one hybrid 13G to back it up.

I plan on gutting my MAS as soon as I get the 2nd gear syncro taken care of. Hopefully soon Batlground will have their second set of rollers installed and I'll be able to dyno it without it costing me an arm and a leg.

And to those that are ripping on Innovator, think about it. He has nothing to gain by sharing this information. He's just trying to make public the gains he has seen from a well known and documented mod. If you don't think it works, don't do it. I don't think it can get much simpler than that. I am going to give it a shot soon. I have nothing to lose but an engine. I'm itching to learn how to do a full rebuild, anyway.

[John Monnin]

Originally posted by ukyo


The only thing Innovator has brought to the table that is new on this mod is the dyno reports and the theory on timing. .......

................What I don't get is why now so many people are listening all of a sudden? Phalse told us about this years ago, and had 11 second time slips on one 9b and one hybrid 13G to back it up.

I think it is the timing issue that has caught everyone attention.

Because it shouldn't work, people don't believe him.
I believe it works on his car him I just think that we just don't quite understand why.

The other reason this caught so many people attention is because it is the only mod he had. A lot of people have gutted thie MAS , at the same time they installed bigger injectors, or bigger turbos, or new intake or new exhaust...

[boostedVR4]

OK, here is a log of my car right now. This is at 1.1 bar, .94 .96 02's, on an 80 degree afternoon. For some reason, I'm getting knock at 5k up. I assumed it was from the turbos heating the air up too much. But, by 5k, they are lucky to be pushing 12-10psi. I'm sure I could get rid of the knock by turning the boost down to 1 bar, and adding a little bit more fuel.

I have already gutted my spare MAF, all I have to do is put it back in, and retune my AFC to get .94 02s. I'll post a log of that after I get it done.

[Quijinn]

You know i agree. Information is being shared. I am interested to see how this works with a AEM controling it. If it does not work well then I will go with a MAP but till them I think this would be a fun experiment.

[Innovator]

Originally posted by John Monnin


I think it is the timing issue that has caught everyone attention.

Because it shouldn't work, people don't believe him.
I believe it works on his car him I just think that we just don't quite understand why.

The other reason this caught so many people attention is because it is the only mod he had. A lot of people have gutted the MAS , at the same time they installed bigger injectors, or bigger turbos, or new intake or new exhaust...

I've actually though of most of these possibilities.

I've decided that using the stock MAF allows the ecu to use certain parameters that do not need to be changed due to HP increases. In fact, some stock parameters are better left alone in many cases. I'm sure the engineers put a lot of thought into the drivabilty and smoothness aspects of the VR4 that some aftermarket MAF systems may diminish or eliminate entirley from the maps. Timing is one of the ones you want to keep a close eye on! . If you don't want knock, you don't want to go way beyond 22 degrees of advance up top. With my stock virgin MAF, my timing went over -29 at times, and that was not a good situation. Ever wonder why the car likes to run rich? Because running rich suppress the knock caused by the excessively advanced timing. Better to run leaner and have slightly less timing from what I've determined ,on this car in particular.

This mod allows more air to enter with less air restriction. Just like any larger MAF, it decreases spool up, which gives the car a snappier feeling, and more overall HP pretty much everywhere across the power band.

Since the Karman readings are lower now (even though there is more flow in theory) the ECU is somehow fooled into reducing the timing. I can't be bothered trying to figgure out why. I probably couldn't anway.

My Karman readings would peak near 2850, but at 2700 they would show a huge dip in flow and make the car go very lean between 5800 and 6400 rpm (13:1). That may be where others have fragged there engines. Just a thought....

Now my max HZ are 2700 @ 7200 rpm. The lower overall airflow value somehow is pleasing to the ECU and tining curve. I also found it was easier to tune a flat A/F reading with the gutted MAF. The MAF reads the increase in airflow smoothly all the way to redline with no spikes or dropoffs as before. So you effectively increase the gross flow accuracy and potential of the MAF. Using a wideband really gives you the edge . You can really feel this as it manifests itself as smoother throttle response and less jerkyness that the high correction factors on the AFC at lower rpmps cause. Keep in mind with 550 injectors, I'm at -15 now as opposed to -31. That will effect the low and partial throttle performance in a positive way.

My timing advance is roughly 6 degrees less advanced . Why it would work on my car and not others as John would suggest is possible is beyond me. I'm no engineer, but I know what works, and I know cause and effect.

The ONLY thing that may effect this mod is the Alamo IC's and pipes I have, flowing many more CFMs than stock units. So it's possible the gains I've experienced may not be as significant with stock IC's and piping to the CFM / restriction loss. Also really big injectors are gonna hurt your performance, mainly if they are too big for your needs. That's a biggy IMO.

Whatever the f*ck.... It works!