How the MAF really works
#142
TECH Senior Member
#144
Launching!
The MAF measurement is one of the most critical to the core function of the PCM. In the absence of the MAF, an airmass estimate is derived from the VE table, measured IAT, rpm, and MAP. But that estimate is only as good as the calibration of the VE table and proper measurements of cylinder air temp and manifold pressure. Sloppy work or bad assumptions in a VE calibration shows up indirectly as poor AFR control, trans performance, idle control and a few other quirks.
#146
TECH Senior Member
Well, the MAF measurement is only as good as the MAF table... the argument goes either way... who calibrated either table...?
Is the MAF table a "calibration" or an "estimate"...?
Is the VE table a "calibration" or an "estimate"...?
(which one is more "valid" than the other...?)
Is the MAF table a "calibration" or an "estimate"...?
Is the VE table a "calibration" or an "estimate"...?
(which one is more "valid" than the other...?)
#147
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Well, the MAF measurement is only as good as the MAF table... the argument goes either way... who calibrated either table...?
Is the MAF table a "calibration" or an "estimate"...?
Is the VE table a "calibration" or an "estimate"...?
(which one is more "valid" than the other...?)
Is the MAF table a "calibration" or an "estimate"...?
Is the VE table a "calibration" or an "estimate"...?
(which one is more "valid" than the other...?)
VE is an estimate because it's a predetermined fueling table(which obviously is used in conjuction with many other sources for fueling).
#149
TECH Senior Member
How is this (MAF table lookup) any different than VE table lookup...?
How did GM arrive at the MAF table...?
How did GM arrive at the VE table...?
How can you say that one is better (accurate) compared to the other...?
#150
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MAF sensor reports in Hz which the MAF table translates to g/s...
How is this (MAF table lookup) any different than VE table lookup...?
How did GM arrive at the MAF table...?
How did GM arrive at the VE table...?
How can you say that one is better (accurate) compared to the other...?
How is this (MAF table lookup) any different than VE table lookup...?
How did GM arrive at the MAF table...?
How did GM arrive at the VE table...?
How can you say that one is better (accurate) compared to the other...?
Yes, quantify?
Total uncertanity of either measurement?
RSS?
#151
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MAF sensor reports in Hz which the MAF table translates to g/s...
How is this (MAF table lookup) any different than VE table lookup...?
How did GM arrive at the MAF table...?
How did GM arrive at the VE table...?
How can you say that one is better (accurate) compared to the other...?
How is this (MAF table lookup) any different than VE table lookup...?
How did GM arrive at the MAF table...?
How did GM arrive at the VE table...?
How can you say that one is better (accurate) compared to the other...?
#152
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#153
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Why should I have to do the work for you?
I'd start by reading:
http://redhardsupra.blogspot.com
Specifically: http://redhardsupra.blogspot.com/200...ss-models.html
Additionally you can read Greg Banish's book.
Take the time to educate yourself and don't expect people to just hand you the information with no effort on your part.
BTW, a good tip is to study the tables in your tuning software, they typically explain exactly what the table is referencing and will answer your questions on how the MAF table functions.
I'd start by reading:
http://redhardsupra.blogspot.com
Specifically: http://redhardsupra.blogspot.com/200...ss-models.html
Additionally you can read Greg Banish's book.
Take the time to educate yourself and don't expect people to just hand you the information with no effort on your part.
BTW, a good tip is to study the tables in your tuning software, they typically explain exactly what the table is referencing and will answer your questions on how the MAF table functions.
#155
TECH Senior Member
In the meantime, who can answer these questions:
MAF sensor reports in frequency which the MAF table translates to airmass flowrate...
How is MAF table lookup any different than VE table lookup...?
How did GM arrive at the MAF table...?
How did GM arrive at the VE table...?
How can one be better compared to the other...?
How is MAF table lookup any different than VE table lookup...?
How did GM arrive at the MAF table...?
How did GM arrive at the VE table...?
How can one be better compared to the other...?
#156
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GM didn't arrive at a "MAF table". A MAF is a sensor, Ford uses a MAF exclusively from what I recall and GM used to use SD(case in point my 2002 Cavalier).
I posted the answers to your questions, if you're going to be an *** about it nobody will want to help you.
I posted the answers to your questions, if you're going to be an *** about it nobody will want to help you.
#157
TECH Senior Member
You didn't answer my questions (you said "Why should I have to do the work for you?")...
and you're missing the whole point of my questions...
and I don't see how I was an ***, would you explain that to me.
#159
Launching!
How did GM arrive at the MAF table...?
Any time you modify some part of the inlet system (cold air kit, MAF sensor, fileter, etc...), you are changing the relationship between actual airmass and Hz. It may go up or down at any point, but it's different. This is why we need to calibrate this table during the tuning process for modified cars.
How did GM arrive at the VE table...?
How can one be better compared to the other...?