[91_Talon_Owner]

In the July '02 issue of Sport Compact Car, their build up of "project Matrix" (pg 244) they state that "XS Engineering took the unconventional route of putting the MAF sensor in the intercooler pipe. This allowed the sensor to be placed after the BOV, preventing the MAF from measuring air vented by the BOV"

Does the Toyota Matrix MAF read in Karman Vortices? If so, can its MAF be integrated into our system?

Here's my idea: (provided the Matrix MAF does indeed read in Karman)
Install the Matrix MAF after the BOV near the TB.
If necessary, install a potentiometer or resistor (whichever is required) in the wires that operate the barometric sensor which is integrated into our MAS. I would like to do this, not really for atmospheric venting, but to reduce the restrictions in the inlet for the turbo. If this operation is possible, I plan on routing a pipe from the turbo inlet to the SMIC location, and putting a low profile, low resistance filter on it there.

Here are the questions:
1: Does the Matrix MAF read in Karman vortices?
2: What kind of CFM is the Matrix MAF capable of counting correctly?
3: Is there a baro sensor that can be integrated into our stock wiring that can be installed into the upper intercooler pipe?
4: What wiring in the MAS harness specifically controls the MAS?
5: What wiring in the MAS harness specifically controls the Baro. Sensor?
6: Are there any more sensors in the MAS that I am not aware of?
7: If the answer to (6) is "yes" can that sensor be bypassed (potentiometer/ resistor) without dificulty? If not, is there a suitable replacement?


Thank you all for your help... I know I am probably not going to get all of my questions answered, but every little bit of information helps.

-Eric McCabe

 

[Amin]

I try to add what I could about the topic here,


Yes there are other sensors in the intake. Barometric Pressure, Air Temperature and the Air Flow.


The output of the Air Flow sensor is a frequency which could or could not be in range of the ECU's accepted values. The design of the Sensor would define if the sensor sends out values between 1Hz to 100Hz or from 20-1000Hz for the SAME amount of air. You might be able to adjust this coefficient somewhat with the Temp and Pres. sensor but I doubt the ECU likes it much if it sees values that are really out of range.


For doing so you can in fact the DSM's own MAS sensor and I don't see why that is hard to be done. You can just make and area along the pipe that immediately goes into your throttle body and stick the MAS subsystem into it.


Remember that the temperature there is REALLY different from the temperature right at the intake.


Under normal condition the exact same amount of air is passing through the intake that passes through the throttle body hose or after the BOV anyways. So you are not gaining anything. Other than having the MAS working in pressure and and more chaotic flow which would probably interfere with its operation.

Due to the centrifuge design of the turbo having the MAS after it would help a bit but nothing that would make any difference because you are limited not to the abilities of your turbo but what you MBC is set at.



Hope this helps
Amin

 

[91_Talon_Owner]

The main reason I am interested in replacing the stock MAS is that it is restrictive, and inaccurate. Moving ithe stock MAS' location closer to the throttle body would be counter-productive, because as you said, that is a pressurized location, not to mention what the turbulence that the air must be like. Putting *our* MAS there, it seems that a misscount would be inevitable. What I am hoping to find is an accurate MAS that will be easily installed into the UICP. It seems that the likelyness of this endeavour are dwindling, however.

Thank you for pointing out that there is also an Air Temp
sensor (ATS).

Upon consideration and much thought, it seems to me that the factory location of the ATS may be a contributing factor to the overall rich condition that is present in our cars from the factory. As you pointed out, the temperature at or near the throttle body
is drastically different (higher) than the near ambient temps that the ATS is reading. The inherent innaccuracy of the ATS (solely due to its location) would fool the computer into thinking that the intake charge is cooler than it really is, causing the ECU to send the wrong ammount of fuel.

So now I am on the hunt for an ATS that is directly compatible with our ECU.
Great.
As if a MAF wasn't hard enough.

So NOW what I am looking for:
(in adition to the q's in my first post)

1: Is there an Air Temperature Sensor that has an output that our ECU will recognise? (one that can be installed at or near the TB)
2: Even if the Matrix MAF does send out a frequency, is that frequency compatible with our own ECU?
3: Does anyone know of a MAF sensor that sends out a frequency that our ECU would recognise? (preferrably a MAF sensor that can be utilised as I have outlined)


Thank you all for your help.

-Eric McCabe

 

[Amin]

I think the location of the factory ATS is as it should be.

The temperature of the air should be measured EXACTLY where its pressure and volume is measured. So if you measure the temperature here and pressure there and volume somewhere else you haven't really gathered any data about the amount of air you have, or technically mass of it.

Perfect Gas Law,
P. V=n R T

P.V~ n T



I don't find the MAS really that restrictive. But my syggestion would be to look for a MAS that makes higher frequency than ours. Dividing frequencies would be DAMN easy where as ultiplying is not as friendly.


Any car that would have that Honey comb should be I believe using Kerman Vortices




Amin

 

[Cjburn2]

From all Toyota MAF's I've seen (early to late 90's) are all of the flapper door variety. They are ALOT more restrictive than the Karman type MAF's. I do not know of their later types but I'll ask a couple friends who work on Toyota's to find out for you.

 

[Redsand187]

Wouldn't it just be easier, and possibly cheaper to get a VPC?

 

[Tweeked]

The Honeycomb style will not work right under pressure. You can use a hotwire sensor instead if you have the circuitry to make it compatible. Our MAF is useless under pressure(if I'm wrong please try it on your car and let us all know the outcome).
Yes VPC is better...and definitley cheaper than trying the stock maf in this config...read new engine(if it runs at all).
Rob

 

[flubyux2]

another perspective

Originally posted by me:

before you say anything, just know i used that little red button. and the stuff i read; it said alot but it really didnt tell me shit.

so, ive just been tossing a few ideas in my head

project scope:

to supply enough cold air to my engine, improve throttle response, accurately quantify and qualify the incoming air charge, and also to improve air flow path .

current problems:

stock MAS is located behind pass. headlight, w/ no cold air supply anywhere. there is no place to cut a hole in order to feed cool air to the filter. intake air temps are consistently averaging 120*F while moving, hotter when idling. incoming air charge has to make deviant and turbulent flow path before entering intake tube.

proposed solution:

mount the stock Mas in new casing to sheild delicate electrical components from weather, and create blow-thru characterisitics in order to improve air flow quality and decrease resistance to flow. also, IAT will be relocated with the entire MAS assem. and will now accuratly measure the air temp. entering the engine, accounting for temp. increase incurred by compressing air, and then reduction of IAT incurred by intercooling.

Project requirements:
must fabricate new canister to seal MAS to UICP
relocate battery to trunk in order to make nec. room
may be necessary to lengthen MAS connector harness

other questions:

will stock MAS encounter possible "dropped counts" or "Overrun"?
Current Hz readings with Lower chambers removed and screw backed out peak @ ~1300, will relocation change readings?
can stock MAS operate in pressurized environment?
will IAT sensor operate better mounted in UICP or Air filter?
will Karman vortices have diff. characterisitcs during positive manifold pressure rather than atmospheric pressure?


disreguard any and all aspects of "BOV venting". lets not bring it up at all.

thanks
chris


__________________

i think the mentality that the stock MAS wont work, is basically the same perspective that people took when creating a Blow thru carburetor forced induction system. the entire operating principle of a carb relies on vaccuum and venturies and what not. and when i first heard about a blow thru carb, i said no way. but after researching more, the carb doesnt really care about positive or negative manifold pressure or ambient pressure as far as fuel metering is concerned. carbs work w/ blow thru forced induction.

im just not sure exactly WHY our MAS wont work on a blow thru system. see, the air is going thru the counter, and isnt that all that matters?

if you think about it, they work the same way. in its original position, the MAS counts the air as it flows thru it. the reason it flows thru it in the first place is because the turbo is drawing air in. it creates a vacuum inside the intake tube, behind the MAS. and the atmospheric pressure is FORCING the air into the MAS and down the intake tube and into the turbo. we would call that 14.7 psia. now what happens if we change the environment a little. we have higher pressure inFRONT of the MAS than there is downstream of the MAS. the pressurized air in the UICP will go thru the MAS just as it would normally. the air creates vortecies when it passes over an irregular surface or past an obstruction. how would pressurizing the air cause the vortecies to act differently?

anyhow, in its current location, lets say for arguments sake; 0:14.7psia.

on a blow thru set up, 0:14.7psig. its the same pricinple causing the air to go thru.

is there a problem w/ compressed air having more O2 per cu.ft than uncompressed air?

i can imagine there being a problem if compressed air and uncompressed air both create the same vortecies. if this is so, the stock ECU would not be able to tell the difference between vortecies caused by air w/ more O2/cu.ft and air w/ normal amounts of O2/cu.ft.

but isnt there a Baro.sensor that the computer uses to reference the O2 content according to its pre-programmed fuel calculations? of course, the IAT sensor would be more accurate if it was placed right the same location; take all measurements from the same point/benchmark for accurate calculations.

someone help me here.

short of actually fabricating a case to mount my MAS and installing it inline, i cant think whether or not it would theoretically work.

lets have some input.

thanks
chris

 

[terrible]

I posted on this not to long ago (moving mas).

Couldn't you just "move" the iat sensor in front of your air filter or in an area close to the intake but not in its path or in on comming air? With the baro sensor, can you not do the same?

 

[flubyux2]

i thought about that too. but if you do that, you wont ever be able to tune the car right.

cuz youll be pulling Atmos. data from an ambient source, which is basically what its doing in stock form. but if you move the Air meter infront of the TB, and after the turbo, you probably should move the Atmospheric data from that same location.

if you counted the air before it goes into the TB, but you Qualify the air data before it enters the air filter it wont ahve the same qualities as the air entering the engine.

say its in the air filter. it reads Baro 97 and IAT 120*F, and then it counts the air at 1600 HZ. the computer knows that the 1600 Hz worth of air is at 97 (what are these units, KPa?) and its 120*F.

but if you count the air at the TB, itll suck in and see 1600 Hz, but if the atmos. sensor is still at the filter, itll read 97 KPa? and 120*F, instead of know what it REALLY is, as it enters the intake. each measurement relies on eachother in order for the ECU to accurately administer fuel...i used that word loosely.

i think the only way we will ever know is w/ Trial and error....

chris

 

[1 fast POS]

I have doubts about this working. The mass of air before the turbo is passing through the maf at low pressure and high velocity. After the turbo it is moving at lower velocity, but much higher pressure. Since the karmen works by measuring velocity, I don't think that the ECU will like it. But if someone wanted to take a poke at this relocation theory, I have a plan. 2 mafs, one original located near the air filter with the karmen sensor disabled, but the other sensors still operating. This will provide the ecu with the actual ambient conditions. The 2nd meter located in the high pressure zone with the meter running, but all other functions disabled. However this will probably require alot of tunning with the super AFC, and 50 or so hail marys. The way I see it is that the meter will measure a very small portion of the actual air, and you will need to really richen the party up.

 

[flubyux2]

i figured there would be a problem like that...

i think i wanna try it and see just how hairy things can get. all i need is a stock Maf air can to weld up and then i can mount it in the UICP and go for a test drive. if it doesnt work, i can always put it back the way i found it and wait for a stand-alone.

thanks
chris

 

[91_Talon_Owner]

Well, I've pretty much given up on trying to use a MAF from any other car on ours.
My next idea is to replace our MAS with the most accurate air metering device out there: __________ (please fill in the blank)
I intend to use the above (in conjunction with a new baro sensor, and a new intake temp sensor. All three would be mounted to the Upper intercooler pipe, between the BOV and the TB.)
The only thing holding me up is the fact that I will need a *very* programmable stand alone, and from what I have read/experimented with, the AEM standalone seems to fit that bill. Unfortunately, not much is know on how accurately things can be manipulated using the AEM.

I have decided on NOT using the VPC for two reasons:
1: it is no longer being made, and the price for it is outrageous.
2: from what i understand, using a VPC in a climate that has a tendency to change on a regular basis (NORTHERN MICHIGAN) is bad for streetability. (it doesn't compensate well for changes in temperature, humidity, and barometric pressure, all three of which can change in a matter of minutes where I live)

This really sucks. I was hoping to make the toyota MAF work, but i don't have the time to experiment with shit. hopefully within the next year or so, there will be at least a few knowlegable people who know how to *really* tune the AEM.
God I wish money grew on trees.

-Eric McCabe

 

[1 fast POS]

The question really is, how streetable are the Haltech stand/alone systems? I am lead to believe (by one of there sales reps) that it is really easy to make changes to, on the fly or at home. Bottom line is that the Haltech stand alone systems run on some F()@%!#G FAST cars. If they are street freindly, then sign me up.

 

[Rdy2race]

no bottom line is thayt any needed changes will have to be done with a lap top the tuning box is to crude with out real #'s. Motors cost to much to play with

another. Crank triger needed as the stock CAS won't wotk with huge injectors and modded CAS to run semi sqc. is not accurate enought to synk events ( more costs )

The inabiluity to pass 16MS inj time. this pushes you in to huge inj and that make idleing and running of the car VERY hard and in times not possable.


Much better systems are out other then haltech and with more info in what your looking for you will find them


Pro M MAS : we have run them on stangs with prochargers. Not the best IMHO as the placement of the pick up had to be on the outside of the pipe or it wouldn't run right at idle as the air flow was to slow in the pipes and the pickup was being missed. In short the MAS systems are nice but have some problems and the heat of a VERY hard running car can cause it to fail ( and be injectsed!!) and speed dencity is a guessing game to some extent and with out proper tuning is a bomb waiting to be lit.

Good topic
BM-

 

[1 fast POS]

Let me start this off by saying that I DO NOT believe that we can mount any type of air flow meter AFTER the turbo.
The Karmen sensors read velocity in a given space, at a given temp, at a give pressure. The pressures and temperatures POST turbo would be OFF the charts, and the ECU would be like, uh uuuhh u uhhhhh.
Now the Karmen sensor alone POST turbo still will not work because it is reading air velocity at a given speed, in a given space, at a pressure, all of these readings are far beyond the ECU's education.
I DO NOT believe that a hot wire sensor POST turbo will work either, because the hot wire reads air volume by it's ability to cool a (control) wire in a given space at a given temp. Now POST turbo the variances in temperature that go hand in hand with the turbo will F()@# that idea up.
So I am moving on from from the POST turbo idea for now, because I can't see any great benefit in having it set up that way, only problems. I'm not saying it can't be done , I am just saying it will be a hassle.
Back to the original topic. Which was how can we hook up a less restrictive mass?
I am sure that the original MAF can be modified to read only air temp and barometric pressure. Then add a bigger Karmen AFS to the picture and you are in business. I think that there is a Karmen sensor floating around the J yards that flows more air and feeds the same frequencies. Does anyone know what frequencies that the DSM maf transmits? I would think that anyone with a super AFC could answer that question. For example, I have a Supra (7MGTE) that reads anywhere from 25HZ at idle to 1700HZ at full throttle. If the DSM mass was in the same perameters then we could make that swap, or even better yet the 400 series Lexus has an even bigger Karmen sensor.
Bottom line is that there is a Karmen sensor that will fall into the same perameters, and it will be a direct bolt on. Then we will all look back at this discussion and laugh and say that is where we got the idea to use the MASS out of a ------------?


(by the way I graphed a karmen air sensor on to a 3" ID piece of pvc and reinstalled it back into the 7MGTE. I then did my best to make it run with the AFC, and run it did, like SHIT. However I am yet to give up, I am working on a new baffle to take the turbulence out of the air. I'm sure that is the problem.)