MAF Sensor
12-30-2002, 01:25 PM
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MAF Sensor
Ok, I know you guys don't know me, so take this as you will. I havn't seen much posted on this subject, so I'm putting it out there in case anyone was wondering.
I recently was doing some testing and a bunch research into the possibility/requirement of replacing the stock MAF sensor on my Tiburon for NA tuning applications.
While I feel like I could write a short point paper on the technical details but I'll cut to the bottom line so you'll have the information and anyone that is interested can email me for the math and technical backup.
Basically, the only time you would need to consider upgrading the MAF sensor to a larger unit would be in a max NA configuration. That is, a complete engine rebuild with 61MM TB/IM (or double or quad TB), racing cams, upgraded fuel system, lighted rotating mass, higher compression, etc.
If you stick with a 58MM TB/IM and a mild cam, the stock MAF will serve very well. As will the stock fuel system and ECU.
Reasonably within these parameters, you still should be able to gain about 10-15 HP and an equal amount of torque across the entire RPM range and still be completely streetable, including emissions (which is important for some folks).
I recently was doing some testing and a bunch research into the possibility/requirement of replacing the stock MAF sensor on my Tiburon for NA tuning applications.
While I feel like I could write a short point paper on the technical details but I'll cut to the bottom line so you'll have the information and anyone that is interested can email me for the math and technical backup.
Basically, the only time you would need to consider upgrading the MAF sensor to a larger unit would be in a max NA configuration. That is, a complete engine rebuild with 61MM TB/IM (or double or quad TB), racing cams, upgraded fuel system, lighted rotating mass, higher compression, etc.
If you stick with a 58MM TB/IM and a mild cam, the stock MAF will serve very well. As will the stock fuel system and ECU.
Reasonably within these parameters, you still should be able to gain about 10-15 HP and an equal amount of torque across the entire RPM range and still be completely streetable, including emissions (which is important for some folks).
12-30-2002, 11:39 PM
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QUOTE
Mav:
And then?.....
So you managed to get a larger MAF?....or you are looking for one....or....
Me confused.
No, there are NO aftermarket MAFs available. Anything of the sort would have to be custom built, and though I have some ideas on the subject, I have no need of one. After doing the research (and lots and lots of math) I decided to just stay within the parameters allowed by the stock MAF/ECU.
And then?.....
So you managed to get a larger MAF?....or you are looking for one....or....
Me confused.
12-30-2002, 11:50 PM
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The stock MAF is good for about 250 wheel horsepower, and you will never reach that normally aspirated in one of the four cylinder motors. Koreans are lucky to get 200whp NA out of these things.
There was some speculation about simply wiring up a different MAF from like a Sonata or something, but honestly you'll probably cause more problems than solutions.
Whatever MAF sensor you strap on will need to be calibrated the same way that our current MAF is, or else will have to come with a new set of injectors.
There was some speculation about simply wiring up a different MAF from like a Sonata or something, but honestly you'll probably cause more problems than solutions.
Whatever MAF sensor you strap on will need to be calibrated the same way that our current MAF is, or else will have to come with a new set of injectors.
12-31-2002, 04:15 AM
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Blue2000, yeah, I was pretty sure that nobody made aftermarket MAFs, I was confused by what you were trying to say, my bad. 
Red, could you use a sonata MAF if you were to use a Haltech(full ECU) and larger injectors, the whole 9, etc.? Does the aftermarket ECU require a specific MAF per motor size, or am I clueless?
I probably am, but am interested to know anyways.
Red, could you use a sonata MAF if you were to use a Haltech(full ECU) and larger injectors, the whole 9, etc.? Does the aftermarket ECU require a specific MAF per motor size, or am I clueless?
I probably am, but am interested to know anyways.
12-31-2002, 04:37 AM
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If you go so crazy as to install a Haltech unit, you throw away the MAF. For that level of tuning, MAP is the only way to go, and the Haltech unit comes with a 1 bar, 2 bar or 3 bar manifold absolute pressure sensor for your tuning pleasure.
Which, if you're wanting to make more than 250 horsepower, Haltech is the way to go.
Which, if you're wanting to make more than 250 horsepower, Haltech is the way to go.
12-31-2002, 04:38 AM
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If you have a haltech... you wont need to use a MAF sensor...
To add... our stock internals can take any NA abuse you can give to them...
You dont have to build up the block
Some knife edging and higher compression would help...
Get ready to spend A LOT of money... and in the end, some punk *** with some bolt ons and a 75, will still leave you looking at tail lights
frown
To add... our stock internals can take any NA abuse you can give to them...
You dont have to build up the block
Some knife edging and higher compression would help...
Get ready to spend A LOT of money... and in the end, some punk *** with some bolt ons and a 75, will still leave you looking at tail lights
frown
12-31-2002, 04:59 AM
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Thats true. I guess it all depends on what is your end goal. In my case, I use my car for autocross and track days (solo1 style), where I need the power increase across the entire RPM range (but not so much that I move up classes)and available for more than straight line acceleration. For me, NA is the way to go.
If I was drag racing, pro-solo or pro-rally, I'd look seriously at a small turbo or (more likely) a supercharger.
Anyway, I'm not worried about the punk*** showing me thier tail lights.
Red, I wish I had known about this board a couple weeks ago. I could've asked you and saved myself a lot of work. On the other hand, i wouldn't have known the right question to ask...so I guess getting educated is better in the long run. smile.gif
If I was drag racing, pro-solo or pro-rally, I'd look seriously at a small turbo or (more likely) a supercharger.
Anyway, I'm not worried about the punk*** showing me thier tail lights.
Red, I wish I had known about this board a couple weeks ago. I could've asked you and saved myself a lot of work. On the other hand, i wouldn't have known the right question to ask...so I guess getting educated is better in the long run. smile.gif
12-31-2002, 06:32 AM
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Well then, maybe I should be a tad more inclusive with my explanation...
MAF sensors report airflow by sending a certain amount of voltage to the ECU, varying between 0 and 5 volts DC. More air = more voltage sent.
The problem is that MAF sensor voltage is not linear with respect to airflow. For example:
Air flow (lbs/min) Voltage Return
1....................0.50vdc
2....................0.65vdc
3....................0.85vdc
5....................1.00vdc
8....................1.40vdc
10...................1.65vdc
12...................1.80vdc
15...................2.00vdc
18...................2.45vdc
20...................2.75vdc
25...................3.20vdc
30...................3.85vdc
35...................4.45vdc
You get the idea, this is just a general example. Let's say that table above is the method in which the stock MAF sensor on our 1.8L / 2.0L engines works. Notice that doubling airflow does not necessarily result in doubling of voltage.
However, because the cooling effect of the air passing the hotwire or hotfilm resistor in the MAF, a bigger MAF usually results in lower voltage return for the same amount of airflow. The stock 55mm MAF sends 1.65v for 10lb/min of airflow, whereas perhaps an aftermarket 65mm MAF would have sent 1.15v for the same 10lb/min of airflow.
So, simply strapping on a bigger MAF sensor will almost always result in the car getting leaner... The bigger MAF is sending less voltage for the same airflow, but the ECU doesn't know you've changed anything. Thus, it interprets lower MAF voltage as simply less air coming in, so it sends less fuel. Oooooops...
Either you need a MAF sensor that is calibrated to match your stock setup, OR you need bigger injectors. Why bigger injectors?
Let's say that your new MAF sends 50% less voltage than the stock MAF for all possible airflow values. The stock ECU doesn't know what you've done, so normally the ECU would send 50% less fuel as a result. Of course, you'd be lucky if the car even starts with that kind of lean condition.
What you can do is oversize the injectors to compensate for the MAF. A 50% reduction in fuel signal will require a 100% upsized injector to compensate. Thus, you would strap in a set of 500cc injectors with your special MAF sensor and suddenly it will all start working again. The ECU thinks it's only sending half the fuel, but since the injectors are 2x bigger than stock, 1/2 x 2 = 1. Or in less math terms, half the fuel flow of a double-sized injector is equal to one normal injector.
Make more sense now? smile.gif
This is rudimentarily how you can use an S-AFC to fool the stock computer into running 440 or 500cc injectors. By cutting the voltage return in half, you can use double-sized injectors without flooding the car and without replacing the stock ECU.
[ December 31, 2002, 01:36 PM: Message edited by: Red ]
MAF sensors report airflow by sending a certain amount of voltage to the ECU, varying between 0 and 5 volts DC. More air = more voltage sent.
The problem is that MAF sensor voltage is not linear with respect to airflow. For example:
Air flow (lbs/min) Voltage Return
1....................0.50vdc
2....................0.65vdc
3....................0.85vdc
5....................1.00vdc
8....................1.40vdc
10...................1.65vdc
12...................1.80vdc
15...................2.00vdc
18...................2.45vdc
20...................2.75vdc
25...................3.20vdc
30...................3.85vdc
35...................4.45vdc
You get the idea, this is just a general example. Let's say that table above is the method in which the stock MAF sensor on our 1.8L / 2.0L engines works. Notice that doubling airflow does not necessarily result in doubling of voltage.
However, because the cooling effect of the air passing the hotwire or hotfilm resistor in the MAF, a bigger MAF usually results in lower voltage return for the same amount of airflow. The stock 55mm MAF sends 1.65v for 10lb/min of airflow, whereas perhaps an aftermarket 65mm MAF would have sent 1.15v for the same 10lb/min of airflow.
So, simply strapping on a bigger MAF sensor will almost always result in the car getting leaner... The bigger MAF is sending less voltage for the same airflow, but the ECU doesn't know you've changed anything. Thus, it interprets lower MAF voltage as simply less air coming in, so it sends less fuel. Oooooops...
Either you need a MAF sensor that is calibrated to match your stock setup, OR you need bigger injectors. Why bigger injectors?
Let's say that your new MAF sends 50% less voltage than the stock MAF for all possible airflow values. The stock ECU doesn't know what you've done, so normally the ECU would send 50% less fuel as a result. Of course, you'd be lucky if the car even starts with that kind of lean condition.
What you can do is oversize the injectors to compensate for the MAF. A 50% reduction in fuel signal will require a 100% upsized injector to compensate. Thus, you would strap in a set of 500cc injectors with your special MAF sensor and suddenly it will all start working again. The ECU thinks it's only sending half the fuel, but since the injectors are 2x bigger than stock, 1/2 x 2 = 1. Or in less math terms, half the fuel flow of a double-sized injector is equal to one normal injector.
Make more sense now? smile.gif
This is rudimentarily how you can use an S-AFC to fool the stock computer into running 440 or 500cc injectors. By cutting the voltage return in half, you can use double-sized injectors without flooding the car and without replacing the stock ECU.
[ December 31, 2002, 01:36 PM: Message edited by: Red ]
12-31-2002, 08:59 AM
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An excellent explaination, red. Thats about as far as I got in my research though, since I determined replacing the MAF wasn't necessary, I kindof dropped the whole idea.
I didn't think about what modifications would have to be done. Wouldn't I have to know the voltage outputs for both sensors at the same airflow to do what your suggesting? To figure out what the ratio would be, I mean. If the larger MAF's voltage output was 1/2, 1/3, 2/3, or whatever.
[ December 31, 2002, 05:35 PM: Message edited by: blue2000 ]
I didn't think about what modifications would have to be done. Wouldn't I have to know the voltage outputs for both sensors at the same airflow to do what your suggesting? To figure out what the ratio would be, I mean. If the larger MAF's voltage output was 1/2, 1/3, 2/3, or whatever.
[ December 31, 2002, 05:35 PM: Message edited by: blue2000 ]