How does the MAF work?
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From: US
How does the MAF work? Newbie question. I have searched on MAF and MAF-t, and read a lot but none answer the question.
I know it uses the airflow with a sensor, but what is the output? Resistance, frequency or what? What does the MAF-T do to fool the system? Anyone willing to share info?
Brian
I know it uses the airflow with a sensor, but what is the output? Resistance, frequency or what? What does the MAF-T do to fool the system? Anyone willing to share info?
Brian
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From: Live Oak, FL - in the woods where the creatures lurk.
Re: How does the MAF work? The way I understand it:
Resistance elements have voltage applied as airflow increases to maintain constant state. Voltage applied is converted to frequency.
I assume the MAFT adjusts the output to the pcm to represent a different load.
Resistance elements have voltage applied as airflow increases to maintain constant state. Voltage applied is converted to frequency.
I assume the MAFT adjusts the output to the pcm to represent a different load.
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From: College Station, Tx
Re: How does the MAF work? I believe it's actually current that's varied - voltage is fixed. Other than that same principal.
There is a hot wire and a cold wire that have a certain temperature delta maintained between them (this is why temp doesn't effect the MAF directly) - since heat transfer is a function of temperature delta and massflow (as well as a fixed thermal conductivity value for air) a certain current value which is required to maintain a certain temp equates to a specific massflow level.
The output of the MAF sensor is simply a frequency value - it is not linear with airflow though. There is a lookup table inside the pcm which converts this value to massflow.
The maf-t samples this value, probably converts it to a massflow, applies a scalar to it, then converts it back to requency (to ensure you have a flat %change across the board)
http://www.slowcar.net/shared/FREQUENCY_MAF.PDF
there is a GM/Delphi whitepaper on the MAF functioning that should answer most of the other questions.
Chris
There is a hot wire and a cold wire that have a certain temperature delta maintained between them (this is why temp doesn't effect the MAF directly) - since heat transfer is a function of temperature delta and massflow (as well as a fixed thermal conductivity value for air) a certain current value which is required to maintain a certain temp equates to a specific massflow level.
The output of the MAF sensor is simply a frequency value - it is not linear with airflow though. There is a lookup table inside the pcm which converts this value to massflow.
The maf-t samples this value, probably converts it to a massflow, applies a scalar to it, then converts it back to requency (to ensure you have a flat %change across the board)
http://www.slowcar.net/shared/FREQUENCY_MAF.PDF
there is a GM/Delphi whitepaper on the MAF functioning that should answer most of the other questions.
Chris
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Re: How does the MAF work? Interesting paper. So if it's a frequency, then theoretically, if the frequency is altered, then the PCM would think a different amount of air is flowing. Hmmmmm...Now the next question is how to *manually* advance the timing with an obd II engine. If the engine uses a crankshaft sensor and camshaft sensor, I assume that both of the trigger points for each sensor would need to be moved otherwise a code would be set?
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Re: How does the MAF work? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">You would need ls1 edit or ed wright programming to edit the timing table.</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">So you're saying moving the triggers for the sensors wont do anything to the timing? What I'm trying to do is leave the PCM code stock without any changes.
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From: Murphy, TX
Re: How does the MAF work? Why?
People have been dying to get rid of this hackish "signal conditioning" nonsense for some time. (If they haven't they should have. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> ) Add up the cost for various bits of trickery and you'll see that you come out ahead with programming, and even farther ahead with a programming tool.
People have been dying to get rid of this hackish "signal conditioning" nonsense for some time. (If they haven't they should have. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> ) Add up the cost for various bits of trickery and you'll see that you come out ahead with programming, and even farther ahead with a programming tool.
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From: College Station, Tx
Re: How does the MAF work? The sensors are integral parts of the camshaft and cranksahft - relocating them would be a huge undertaking, and you would also be altering injector phasing as well as timing.
Plus there may be all sorts of other effects - the problem with your technique is that all the sensors have multiple effects, so in a *best* case scenario your changes end up having unintended effects.
On the other hand you can buy ls1 edit, make what changes you desire, and if you want stock pcm code spend 3 minutes to flash your stock program back.
Chris
Plus there may be all sorts of other effects - the problem with your technique is that all the sensors have multiple effects, so in a *best* case scenario your changes end up having unintended effects.
On the other hand you can buy ls1 edit, make what changes you desire, and if you want stock pcm code spend 3 minutes to flash your stock program back.
Chris
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Re: How does the MAF work? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Why?</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Do I really have to say why? <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> It's all about rules. If I can figure out how these sensors work without altering the pcm code, then I may be able to catch the guys that have already figured it out. See? I agree that it would be easier to use LS-edit, but, the rules makers can simply rewrite my computer with a stock map, and there goes all the hard work with the mapping. But say now, I alter the workings of the MAF, and the crankshaft/camshaft sensors to help at (say) WOT, that advanced timing would be easier to hide. I wouldn't be relocating the sensors, but slightly altering their position. I'm talking milimeters here. Sure they could change those parts with a stock one, but when the parts already have a OEM part number on them...
So now that I've let the cat out of the bag...Is there a way? PM me if you have to. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
<small>[ May 01, 2002, 10:48 PM: Message edited by: battmain ]</small>
So now that I've let the cat out of the bag...Is there a way? PM me if you have to. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
<small>[ May 01, 2002, 10:48 PM: Message edited by: battmain ]</small>
