NSSANE02

iTrader: (14)

I know on a stock tune the computer will adapt, or tune itself to most mods but my car has been tuned already (dyno tuned) is it still able to tune itself? I ask because I just ported my MAF ends and it is quite a bit slower some how.

billybob1142

maybe your car is just gay... ever thought of that?

ZL1Killa

iTrader: (17)

your car doesn't "tune itself" there is a variance of it reading the AFR and adjusting WITH FUEL TRIMS, which can screw up your WOT... if they are negative you may go lean...if they are positive you may go rich into WOT...

if you simply just ported the MAF ends, I do not see how porting would throw you off at all. Now if you de-screened the MAF i would see your car running leaner than normal and you would want to TUNE that in

but just porting...naw, no way not JUST on the MAF

2xLS1

iTrader: (25)

You might want to rethink that.

turbolx

Sorry, but this couldn't be more wrong.

You have to look at how a MAF works in the first place to understand what's going on here. The MAF doesn't measure every single air molecule entering the engine, only a few. But it ASSUMES that for every one molecule of air hitting the wire element (being measured by heat transfer), there are a fixed number of other molecules passing through the open space of the MAF. If you port the MAF sensor housing to open up more space for these additional molecules to flow through, the relationship between measured air and actual air changes. Even worse, the change is not completely linear across all operating conditions. The effect can be different at low vs high airflow rates, depending on how you "ported" the housings. Sure, the PCM will try to "learn" via fuel trims, but that will only get it so far. The PCM does not have the ability to learn in the top end of WOT flow, so if the difference there is not the same as where it was actually doing correction, you have yet another source of error.

Bottom line: If you modifiy the MAF sensor in any way, the tune must be changed to reflect the new g/sec - Hz relationship. This usually means doing some steady state testing with a wideband and taking careful measurements. It's not difficult to fix, but still necessary if you want to hit the desired AFR at all conditions.

Steel Chicken

iTrader: (3)

if the MAF airflow was significantly changed, the MAF table needs to be recalibrated. it will not self correct.

lt170chevelle

iTrader: (2)

well said ...my question is... is there an average number to raise or lower the table by to get it close without a wideband? i unfortunately descreened and totally ported out my stocker when i first got my hands on my motor few years ago,and am very curious on what i can do to my tables to compensate for this. and right now i dont have access to a wideband.

qqwqeqwrqwqtq

A ported maf is basically junk. Even if you try to retune for it, the maf will never be as accurate and repeatable as stock.

BanditTA

iTrader: (3)

Note worth your time, move on to bigger and better things....

LS1-450

iTrader: (33)

+1....get another MAF. The salvage yard will have one for $25 or so.

moehorsepower

iTrader: (3)

+1, Myself and most tuners will not even attempt to tune a car with a ported MAF, Get a stocker and yes your fueling will be way off........

2002_Z28_Six_Speed

iTrader: (19)

+++ You could make it work, but, it just wouldn't be the same.

YellowToy/A

iTrader: (1)

If you think a ported MAF cant be tuned you must never have tried it. I have a ported 85 MAF. With a wide band a HP tunes it is easy to tune. Works great. If you have a wideand and tuning software it is a great mod. If not dont to it. Only good post in this mess is trubolx.

Super Speed

iTrader: (8)

Might as well get a 85 mm maf

ZL1Killa

iTrader: (17)

it all depends on how far you decide to go with porting

i prefer to polish the MAFs ... perdy

Sabre002

iTrader: (7)

it can be tuned out I have a 104MM LS7 MAF just need to get a table for the size pipe the maf is in.

Frost

iTrader: (45)

same thing applies though.... hell, I have tuned a MAF with the owner watching and merely rotated it 90 deg in it's couplers and thrown the calibration off just to drive that point home to a customer that kept continually changing his intake piping.

Here's the deal, you put in what you want to run, you tune it, and you LEAVE IT ALONE until you are ready to retune the setup.

I don't even understand the rabid fanatacism that people have with MAF porting/swapping/other modifying... It's always some guy with bolt ons claiming it's an airflow restriction too.

Frost

iTrader: (45)

Yeah, don't hold your breath waiting for that one to work out. It will however calibrate just like any other MAF with your wideband.

SIC LSX

iTrader: (10)

I ported my maff and it made its a touch leaner like bairly at all, not enough to hurt anything! Im tuned in Sd now so i dont have to worry about it LOL My ported maff i would sale if anyone would wants it

Frost

iTrader: (45)

If you get your car tuned (or do the cal yourself) and then you change the AFR, what was the point of being tuned? I've *NEVER* seen a ported (butchered) MAF that only moved stuff "a touch leaner", it's always drastic, like 10-20% depending on the hack job.