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Joined: Aug 2002
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Originally posted by ButtonPuncher:
Wow, Stazi. I hope that you don't teach for a living. 
Nobody has ever listed the operational limits for our MAF. What are the tolerances and within what temperature range? If the MAF is trying to keep the wire at 400F, even a crappy intercooler dumping out 200F should be within range.
Also, I'm guessing that the PCM biases the MAF readings based on the IAT. Again, within what limits?
Until someone lists specifics, we can only figure it out through trial and error.
Calling people retarded just because they are trying to learn just isn't cool. 
BP
Then stop guessing and start learning. If you want to learn about FI and Fords, look into what Focus and Mustang owners are doing and you will see what applies to us. CEG is not a one stop shopping source for info.
The IAT does only one thing, see what temp of air your engine is taking in. The PCM uses that info, not the MAF.
A MAF sensor allows the PCM to see how much air the engine takes in by trying to keep a wire heated a specific temp w/ 0-5 volts. More air = more volts to keep the wire heated. .... less air needs less voltage to keep it heated. When you have a turbo blowing it's charge right on it, what would you think that's doing to the MAF and how accurate it would be?
There are MAF's designed to be used as blow through by SCT, Pro-M, ect. But OEM MAF's are better used as draw/suck through.
2005 Ford F150 SuperCab FX4
1964 Chevrolet Impala SS
1998 CSVT: 354HP/328TQ @ 10 psi, now gone 
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CEG\'er
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I believe you can use an stock OEM MAF as a blow-thru with the SCT because there's adjustments the tuning program will do to the signal to compensate for those changes. You just tell it what kind of MAF you have and if it's draw or blow and it's good to go. But yeah,you need it chipped properly not just slapped on.
2000 Rio Red I4 Cougar
200whp & 210wtq at 9psi
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SCT is where I'm getting my info from. In the data provided in their training manual, they talk about how it's not a good idea to use OEM draw through type MAF as a blow through because it reduces the resolution 20-30%.
After looking at the trial and error many of the Focus owners have been going through, they all switch over to a draw through setup. This is on the support forum for SCT PRP currant users and simply things I've come across in my research.
2005 Ford F150 SuperCab FX4
1964 Chevrolet Impala SS
1998 CSVT: 354HP/328TQ @ 10 psi, now gone
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Seawulf, thanks.
Swazo,
The PCM must be able to compensate for temperature changes. If it is a -10F Janurary day or a 180F August traffic jam day. The only way to do this is to take readings from the IAT and bias the readings from the MAF. Everybody is just flat out bitching that it won't work right. From what the Focus guys are doing, it sure seems to work. Is there proof that it doesn't work? If so, what temperature was the air when the readings became totally inaccurate?
Personally, I have seen 180+F intake temps while using the CTA intake in the summer. Nothing blew up, but it sure ran like crap. The PCM was obviously pulling all of the timing due to the insanely high intake temps. From that info, we can tell that the MAF can do it's job up to 180F.
BP
Ben ---'96 Contour GL * Zetec ATX * Tan on Black steelies---
+++JRSC M62 Under Construction+++
My big-a$$ mod list. 
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Yes. Heat will mess up the mafs ability to measure. Something about the way it uses heat in its measuring method doesn't work as well when it is already very hot air.
The whole point of a blow through maf is usually due to packaging problems and stalling issues. If you have to use three feet of piping then what is the point!
There is a parameter in the code that relates size of the intake manifold in liters for the pcm; basically it helps the pcm determine how much air is behind the maf when it senses a throttle position change and an increase in airflow at the maf. That will help it reduce lean conditions and initial throttle tip.
Long story short, I use a my maf in a draw through configuration with a total piping length of about 3-4 feet. I have no issues with it.
Former owner of '99 CSVT - Silver #222/2760
356/334 wHP/TQ at 10psi on pump gas!
See My Mods
'05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red
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Originally posted by ButtonPuncher:
Seawulf, thanks.
Swazo,
The PCM must be able to compensate for temperature changes. If it is a -10F Janurary day or a 180F August traffic jam day. The only way to do this is to take readings from the IAT and bias the readings from the MAF. Everybody is just flat out bitching that it won't work right. From what the Focus guys are doing, it sure seems to work. Is there proof that it doesn't work? If so, what temperature was the air when the readings became totally inaccurate?
Personally, I have seen 180+F intake temps while using the CTA intake in the summer. Nothing blew up, but it sure ran like crap. The PCM was obviously pulling all of the timing due to the insanely high intake temps. From that info, we can tell that the MAF can do it's job up to 180F.
BP
I don't disagree that people need to try things to see how they work. However, you are taking it to another level without doing and critical thinking on the subject.
The IAT is independent of the MAF. It ONLY tells the pcm the air temp.
The MAF is a hot wire "differential" type of measuring device. Meaning:
It measures the changes in resistance between two wires based upon the mass of the air striking the two wires AND on the amount of current that is being introduced. This was calibrated at 1 atmosphere of pressure, not 1.5 to 2.0 atmospheres like you would see in a turbo with blow through maf!
Basically, small difference between the two wires means less dense air, therefore LESS AIR MASS entering the engine.
Density is directly related to temperature so the maf is designed with those factors in mind. All this differential measurement is done by the sensor electronics. All the PCM does is determine air mass from the voltage it senses. If the air is already hot and compressed, that is going to really throw the voltages off no matter what temps the IAT is reporting.
So stop crying that no one posts anything, at least listen to the wisdom being passed your way, then go out and do what it is you think you should do AFTER you have weighed your options.
Remember, we don't have the data to post for MAF calibration voltage/mass at anything above 1 Atmosphere of pressure and a nominal temperature range.
And another thing: How many different variables are you talking about when you say the Focus guys can make it work right? 3, 4?
The end result is a good air fuel. If your maf reacts a certain way (ie always a bit lean under boost because of the error) then you can either fix the problem with the maf or you can change the fuel delivery by injecting more fuel. You can vary it due to throttle position, boost pressure, MAF voltage, and IAT. If you can program then you can compensate for a problem like that.
This doesn't mean that you picked the appropriate solution.
If it were me, I'd look into other ways to fix the stalling on the zetec.
Former owner of '99 CSVT - Silver #222/2760
356/334 wHP/TQ at 10psi on pump gas!
See My Mods
'05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red
'06 Mazda5 Touring, 5spd,MTX, Black
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Hard-core CEG'er
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Originally posted by Seawulf:
I believe you can use an stock OEM MAF as a blow-thru with the SCT because there's adjustments the tuning program will do to the signal to compensate for those changes. You just tell it what kind of MAF you have and if it's draw or blow and it's good to go. But yeah,you need it chipped properly not just slapped on.
You still will have ALL THE PROBLEMS listed in this thread. PERIOD. I don't care who tunes it.
All SCT is going to do it richen up the MAF transfer by 20-30% (that "guesstimate" they state) in hopes you won't run lean. That's gambling plain & simple! That's simple hack tuning as well. 
If you want to run a blow through you had better custom dyno tune your setup and leave it running rich. Anything else is Russian roulette with a loaded gun. 'nuff said.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Wow lots of emotional reactivity here, ok I am done playing dr phil. But seriously guys calling people dimwits kinda pisses them off when they are getting advice from people who actually tune zetecs for a living. The car ran ok with the suck through system but it runs much better with the blow through setup. What pisses me off is that one group of "experts" say to do it one way and another group of "experts" claims another. Give me some credit I did the first 5 speed swap when everyone said it couldn't be done without swappping the subframe, I did the first focus engine swap, and I did the first home brew turbo setup on a zetec in a contour in the US. So I may not be an expert but I know my stuff. Also anyone who knows anything about dsm eclipse turbos knows that a blow through setup is what the high horsepower dsm cars use. Thank you everyone for the information you have provided but my engine has not gone boom yet and won't because I don't let it run lean or over 5 psi.
ATX MTX swap, rear drum disc swap, drilled rotors, ported intake, optim throttle body, CAI, 7.5L MAF, adj. fuel regulator, longtube headers, underdrive pulley, no EGR, low inpedence bigger injectors, 2002 Focus Swap
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Good for you for doing what you've done so far. But it doesn't change the fact that you are trying to use the MAF in a function it was NOT designed for and therefore, not capable of working within it's parameters.
The fact that the HOT WIRE MAF uses two wires, the front one being heated and the donstream one measuring the temp of the air as it passes by should be enough to tell you that when you start pumping out air at 3-400F (when it's design limits are probably not much more than 200F), it will go beyond it's measurement resolution and then the PCM will just guess its best guess.
At 5psi, sure the air temp is probably not TOO bad, but start increasing the boost with this setup and you are playing russian roulette.
And of course you are ingoring the simple fact that no turbo will be totally clean of oil through the compressor side - especially at high rpms when you let off the gas as the oil pressure behind the catridge seal will be very high and the corresponding vacuum in the intake will create a lare pressure differential that will suck oil past the seal Eventually this oil will pass through the MAF and dirty it.
I may not be PC in my arguments, but it seems that insults are the only ay to get through to people who choose to ignore THE FACTS.
2000 SVT Turbo 295hp/269ftlb@12psi
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Originally posted by Stazi:
I may not be PC in my arguments, but it seems that insults are the only ay to get through to people who choose to ignore THE FACTS.
Actually insults do you no good in your bitching. Tom and Greg state there points much better without jumping off the deep end with name calling. Stazi your tieraids are hilarious you make yourself look like the ignorant fool by blowing up. Go take some anger management classes for gods sake.
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