This is my first 'Advanced post' but i figured this is where i would find the most interested readers and productive info. If you think its in the wrong section, move it over to 'general' i guess. I just dont want to get yelled at.
I have been doing some searching on the GM MAF and came across the Granatelli Motorsports website (Granatelli from Paxton i wonder?). They specialize in modified MAFs for domestics (Ford/GM) and I came across thier unit for controlling the fuel for these cars. Here is a little info on that and the question will follow:
"Now you can tune your air/fuel ratio for rich/lean conditions in real time using any Windows compatible laptop. Tune to ANY point on air/fuel ratio curve using the full color, easy to understand graphs. Because our system is completely digital there are no knobs to turn and you are not limited to a fixed number of adjustments). AND you can save the information directly to the weatherproof 32 bit integrated processor, bypassing the factory computer. Whether you use factory or aftermarket tuned computers or programmers, our tuning remains contained in the unit. Because complete data logging ability is included you can actually tune in real time on a chassis dyno with wide band 02 sensor or at the track, improving decision making and maximizing performance. You can even program the unit back to stock at any time and save specific tunes to any disk for easy making remote tuning over the Internet a snap "
How great is that? Even thier non-laptop programable unit is far superior to the MAF Translator we currently have:
"This is the same unit as our laptop programmable unit, except it is directly programmable on the unit (no laptop required). The unit contains a digital LED readout with easy to understand up and down arrows for complete air/fuel ratio tuning in real time. This model features 64 points of adjustments, every 100 cycles (far greater tuning capability than competitive models)."
64 points of adjustment?! The Apexi S-AFC has only 12 points of adjustment and is about the same price ($275)
Now to the application part. This hot-wire type MAF replaces the stock Karman-vortex type MAS and must be used with an electronic device to convert the analog voltage signal (representing mass air flow) to the square-wave voltage signal (frequency counts that represent volume air flow) that the Mitsubishi factory engine control unit wants to see. Is there a basic way to translate the output signal of one on these to a Karman-type output that the stock computer could understand?
I know the MAF-T does this, but if someone more knowledgeable than myself could figure a way to simply translate. no adjustments at all. All the adjustments would be done on either the laptop , or on the units programmer. the output of this would simply need to be translated into a frequency reading, so the computer could understand and respond.
So im looking for some Elec. Engineers/Technologists/Technicians or programmers or anybody with a knowledge of the functions of circuitry to chime in here. Is this basic translation process already available in some form?
Just found this little tidbit of info. I wonder if you could run one of these and compensate with a fuel controller? Just a side bar. original question still applies
Bosch versions and GM 5.0/5.7L V8 units produce an analog voltage output, but Hitachi and most AC Delco MAF's send out a square-wave frequency.
If you are interested at all in how both MAF (hotwire) and MAS (karman-vortex) work, here is where i got the information.
A typical MAF has a wire or film element that's kept heated to a specified temperature above ambient (180 deg. F. in Bosch units) and is exposed to intake air. Through a Wheatstone bridge circuit and dedicated electronics, the amount of current required to maintain that temperature becomes the signal to the computer. High air flow obviously has a greater cooling effect than low, but so does the denser air of cold days and low altitudes, so the PCM gets the true data on mass it needs to provide the longer injector pulse width that extra oxygen needs to fire dependably. Bosch versions and GM 5.0/5.7L V8 units produce an analog voltage output, but Hitachi and most AC Delco MAF's send out a square-wave frequency.
Upscale applications of the Karman-Vortex air mass measurement principle can be found on the Lexus LS 400 and '87 and up Toyota Supras. The speed of vibration of a thin metal mirror in the intake vortex is monitored optically to generate a frequency signal that varies according to the mass of air entering the engine. Various Mitsubishi units use sound waves to exploit the vortex idea.
To be fair, the safcII offers (12x2=24 adjustments). Why only settle with 64 adjustments? The e-manage offers 256 adjustments.
I have to agree with you. Skip the $200 for the MAF-Translator and use a basic translator. I would enjoy programming the e-manage where I can clearly see what's going on.
From a technical point of view, you could use a ready made voltage to frequency integrated circuit chip to do the work for you. Nothing complicated about that. The conversion would be linear. It is very unlikely that both our factory MAF and the new meter would coincidently be linear too. To correct that problem, you'd need a lot of adjustment points.
So yeah, it's possible. If my gutted MAF should ever become a problem, or I get bored during the summer...maybe I'll experiment with the idea.
Yeah, where have you been? Its called a MAFT Mass Air Flow Translater .
Umm, read the question before you answer next time:
Quote:
Originally Posted by Antero
From a technical point of view, you could use a ready made voltage to frequency integrated circuit chip to do the work for you. Nothing complicated about that. The conversion would be linear. It is very unlikely that both our factory MAF and the new meter would coincidently be linear too. To correct that problem, you'd need a lot of adjustment points.
Being in Mech Eng. and not Elec. Eng, i dont agree with your statement "Nothing complicated about that"
So i am supposing that I would need a voltage-to-frequency circuit chip going from 0-5V input (output range of MAF) to 0-1600Hz output (input range of ECU)...well those are minimum values.
When you say linear, i am figuring you mean what are the chances that i will find a 'converting chip' that will actually equate 5V to 1600Hz, in a linear fasion from zero up?
I think we are on the same train, i just need some more detailed explanation of what you mean exactly. Also where would one begin to look for one of these voltage to frequency integrated circuit chips?
Down kitty, I was eluding to the fact that why would you want to do that? Just buy an AEM EMS and get it over with if you're looking to do tuning like that. The whole idea of the translator is that its cheaper than going with a stand alone. If you're beyond the piggy back go with a stand alone, otherwise I don't see a point to needing it.
http://www.national.com/ds/LM/LM231.pdf diagram showing how to hook it up.
It operates from 10hz to 11000hz and 0-5Volts (assuming you feed in 5 Volts in). You only need to change some resisitors/capacitors to change the output to roughly 3100hz. Look at the Fout formula. It tells you how to change it. 1606hz is the magic number for dataloggers. They can't report anything higher.
Without this already available IC, making it from scratch would be somewhat difficult using discrete components & transisitors. Having an IC to do the bulk of the work makes life easy. So going from this perspective, "Nothing complicated about that" statement makes more sense.
Example of linear is 0 volts = 10hz, 2.5 volts = 1550hz, 5.0 volts = 3100hz.
If you were to plot the relationship on a graph, it would be a staight line.
Incidently, I studied electrical/electronic engineering 10 years ago.
Down kitty, I was eluding to the fact that why would you want to do that? Just buy an AEM EMS and get it over with if you're looking to do tuning like that. The whole idea of the translator is that its cheaper than going with a stand alone. If you're beyond the piggy back go with a stand alone, otherwise I don't see a point to needing it.
Wow. umm, okay well if you read the post or went to the link you would see some of the benefits that i can clip out of the quote are:
"Tune to ANY point on air/fuel ratio curve not limited to a fixed number of adjustments). save the information complete data logging ability save specific tunes remote tuning over the Internet
A standalone is complete overkill for most people. cost,tuning and using the car to drive to work everyday just dont make it practical for 97% of owners (including me). And the MAFT is just so broad and basic, that you need to buy an AFC to control the fuel anyway. If you could use one of these programmable MAFs, you could convert to a blow-thru, and then get as much control as listed above, for less money. ($200 Translator + $300 SAFC.) Just seemed like a sensible thing to me, so i am tryiing to figure how to apply it to our cars. So on the electronics side. what would be the best way to convert from analog to frequency?
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Laptop Programmable Mass Airflow Sensor ~ Elec Eng, Pgrmrs, & Techngsts
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