Maxed out my MAF
06-28-2004, 02:19 PM
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Maxed out my MAF Mods in sig. Last dyno pulls, I was maxing out my MAF at I think 56khz. Billiumss is doing my tuning, and pointed out that the 98 PCMs have a lower threshold before maxing out versus the 99+ PCMs. (In example, my 98 has like 10 cells of reading whereas the 99+ have 18 cells).
Bill would like to swipe the tables from a 99+ and load them into my 98 PCM, thus giving my PCM the ability to let my MAF max out at a much higher range.
My questions:
1) This can be done just by a simple copy and paste of the tables from PCM to PCM, right?
2) I have an LS6 MAF sitting around that I've wanted to out into my car. Can we load some files to make this work instead?
If you need more info, lemme know. I'll try to supply info as I can
Bill would like to swipe the tables from a 99+ and load them into my 98 PCM, thus giving my PCM the ability to let my MAF max out at a much higher range.
My questions:
1) This can be done just by a simple copy and paste of the tables from PCM to PCM, right?
2) I have an LS6 MAF sitting around that I've wanted to out into my car. Can we load some files to make this work instead?
If you need more info, lemme know. I'll try to supply info as I can
06-28-2004, 02:46 PM
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I doubt its as easy as just copying the table to your PCM. A bigger table uses more memory, and if the memory in your PCM is allocated for another table it would probably mess it up big time. I don't know this for a fact though.
06-28-2004, 04:50 PM
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A '98 would have the same 23 trim cells as a 99 +.
If you mean it trips a error code for going over the max MAF output which is 11,250 Hz where a 99 is like 12,500 Hz it is a simple tuning change to raise that value as to when an error code would trip.
Just copying the MAF values from a 99 would not solve a airflow problem if truely the MAF is undersized.
97 and 98 PCMs are different in design then 99 and newer PCMs, even the wiring to them is different.
The MAF tables for a 75 mm MAF are not as wide as a MAF table for a 85 mm MAF being the 75 mm starts at 1500 Hz where a 85 mm starts at 750 Hz.
You could get a newer model PCM, move around the wires in your PCM wiring loom connector to match the newer PCM and get it flashed for a newer model year like a 2001 that has uses a 85 mm MAF.
If you mean it trips a error code for going over the max MAF output which is 11,250 Hz where a 99 is like 12,500 Hz it is a simple tuning change to raise that value as to when an error code would trip.
Just copying the MAF values from a 99 would not solve a airflow problem if truely the MAF is undersized.
97 and 98 PCMs are different in design then 99 and newer PCMs, even the wiring to them is different.
The MAF tables for a 75 mm MAF are not as wide as a MAF table for a 85 mm MAF being the 75 mm starts at 1500 Hz where a 85 mm starts at 750 Hz.
You could get a newer model PCM, move around the wires in your PCM wiring loom connector to match the newer PCM and get it flashed for a newer model year like a 2001 that has uses a 85 mm MAF.
06-28-2004, 06:18 PM
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The Delphi 85mm MAFs represent the same airflow with
a higher frequency than the 75mm F-body MAF. That's
why the stock 85mms make the cars run pig rich (>25%,
set codes).
If you used the resistor trick like SLP or Pace do, you can
pull these MAFs to "75mm true" with a 2.7Kohm across the
legs as shown here:
http://community.webshots.com/album/95429402bLraTX
or, if you went lower in value, get it to represent the air
with even lower frequency, which is what you need to do
if you're up against the PCM's 11250Hz input limit. Then
you would be on your own, to generate a custom MAF
table that was right for the scaled calibration. But that
is doable, your next limit is 512 g/sec table data max.
If you worked at it incrementally (like, get the car to
zero trims as-is, swap on the Z06 MAF w/ 2.7K, fix
the table by accumulated LTFT error, switch to 2.4K,
fix the table, switch to 2.2K, fix the table, ...) you
could get there without gross drivability problems
along the way - just a lot of learn time and program
sessions.
The table frequency index I believe is part of the OS
and you don't get to change it.
On an A4 F-body you don't have to worry about the
low end of the table, at idle you will be pulling at
about 2000-2500Hz.
a higher frequency than the 75mm F-body MAF. That's
why the stock 85mms make the cars run pig rich (>25%,
set codes).
If you used the resistor trick like SLP or Pace do, you can
pull these MAFs to "75mm true" with a 2.7Kohm across the
legs as shown here:
http://community.webshots.com/album/95429402bLraTX
or, if you went lower in value, get it to represent the air
with even lower frequency, which is what you need to do
if you're up against the PCM's 11250Hz input limit. Then
you would be on your own, to generate a custom MAF
table that was right for the scaled calibration. But that
is doable, your next limit is 512 g/sec table data max.
If you worked at it incrementally (like, get the car to
zero trims as-is, swap on the Z06 MAF w/ 2.7K, fix
the table by accumulated LTFT error, switch to 2.4K,
fix the table, switch to 2.2K, fix the table, ...) you
could get there without gross drivability problems
along the way - just a lot of learn time and program
sessions.
The table frequency index I believe is part of the OS
and you don't get to change it.
On an A4 F-body you don't have to worry about the
low end of the table, at idle you will be pulling at
about 2000-2500Hz.
