MAF info--c5 forum don't know $#%@
02-28-2004, 09:56 PM
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MAF info--c5 forum don't know $#%@ Hi guys--I thought you guys may have more general info on MAF--it is probably the most overlooked thing on the c5 forum--this week I am installing my FAST 90 and 90mm TB on my 436---I still have a basically stock MAF without screen of course and custom ends--is the larger 85mm MAF better--is flow an issue with the MAF or is it more than adequate for our use---If I have to have more TB and intake would it not be reasonable to assume I may not have enough flow through the MAF--me and the guys on my forum can discuss cam profiles, head flow etc all day but the MAF seems to have been overlooked--bottom line I don't want to think my MAF is a restriction---thanks Bill
02-28-2004, 10:02 PM
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The MAF is not overlooked, its simply not a restriction for most applications. Even custom ends cause more trouble then they are worth because of an incorrect calibration in the PCM.
The only FAST 90's so far have been installed on 01+ C5's where they already have an 85mm MAF. What I mean is that nobody knows the answer to your question.
Personally, I'd just throw on a stock Z06 85MM maf and put the proper calibration in the PCM. It couldnt hurt.
http://www.c5howto.com/index.php?article=25
The only FAST 90's so far have been installed on 01+ C5's where they already have an 85mm MAF. What I mean is that nobody knows the answer to your question.
Personally, I'd just throw on a stock Z06 85MM maf and put the proper calibration in the PCM. It couldnt hurt.
http://www.c5howto.com/index.php?article=25
02-29-2004, 12:26 PM
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Z06 MAF and truck MAFs differ only very slightly
in the PCM cal tables, probably not at all in the
actual hardware aside from the screen.
A descreened Delphi 85mm is probably the best
you can do sizewise at any kind of reasonable price.
If you don't want to program the F-body PCM for
the bigger MAF, then you can solder a shunt
resistor across the "live" legs of the MAF and pull
its curve to match the stock F-vody 75mm.
To do this you need a DVM, a soldering iron and
a 2.7Kohm 1/8W Radio Shack resistor. The legs
you want to solder it across can be seen here:
http://community.webshots.com/album/62584862vRyXVK
You only need the DVM if you want to verify the
legs to use; the center of three, to the neighbor with
the 150-ohm resistance instead of <1ohm.
By slight changes in the resistor value you can tweak
the mixture up or down. The bare MAF is roughly 25%
rich, the 2.7K puts it about neutral relative to Fbody
cal, and of course you could go even leaner with a lower
value.
If you find yourself a used Z06 MAF you will save yourself
the 2 minutes of effort in descreening; if you prefer the
screen for safety reasons or you have a very non-straight-
shot intake, then get a truck MAF.
The MAF table on that 'Vette page should get you within
a percent or two for a truck MAF (there is even info for
screened vs descreened) if you decide to go the PCM
tuning route.
in the PCM cal tables, probably not at all in the
actual hardware aside from the screen.
A descreened Delphi 85mm is probably the best
you can do sizewise at any kind of reasonable price.
If you don't want to program the F-body PCM for
the bigger MAF, then you can solder a shunt
resistor across the "live" legs of the MAF and pull
its curve to match the stock F-vody 75mm.
To do this you need a DVM, a soldering iron and
a 2.7Kohm 1/8W Radio Shack resistor. The legs
you want to solder it across can be seen here:
http://community.webshots.com/album/62584862vRyXVK
You only need the DVM if you want to verify the
legs to use; the center of three, to the neighbor with
the 150-ohm resistance instead of <1ohm.
By slight changes in the resistor value you can tweak
the mixture up or down. The bare MAF is roughly 25%
rich, the 2.7K puts it about neutral relative to Fbody
cal, and of course you could go even leaner with a lower
value.
If you find yourself a used Z06 MAF you will save yourself
the 2 minutes of effort in descreening; if you prefer the
screen for safety reasons or you have a very non-straight-
shot intake, then get a truck MAF.
The MAF table on that 'Vette page should get you within
a percent or two for a truck MAF (there is even info for
screened vs descreened) if you decide to go the PCM
tuning route.