BOTTLE ROCKET

iTrader: (4)

OK, based on the post about a ported MAF being "junk" I am buying one to replace the one on my car that I ported a couple of years ago after being convinced it was free hp.
My question is; Should I buy one "descreened", stock and remove the screens ONLY, or stock and leave stock?
I've got a H/C C5 with EVERYTHING. Fast, Ported 90 TB, headers, etc...
I've also got HPTuners on the way, and will be training intensly if there's somthing I should change.
Thanks

Ed Wright

iTrader: (1)

If you have Hptuners on the way, save yourself some money and re-scale the MAF table to correct your fueling.

BOTTLE ROCKET

iTrader: (4)

But if it's ported, how can I determine (measure) how much air is actually flowing through the MAF housing. Based on the "other" MAF post, once one's been ported, there is no way to measure and thus compensate for the new airflow.

YellowToy/A

iTrader: (1)

The way u tune is the get the command air fuel ratio to be the same as the actual. Set the cammand a/f ratio to 12.8 then tune the the maf table until you get it. Then dont change the intake track.

Gh0st

iTrader: (3)

Don't listen to them, they don't know what they're talking about. Just recal your MAF fuel table and you're good to go.

YellowToy/A

iTrader: (1)

Ghost good advice but how do you do that?

wait4me

iTrader: (10)

The problem with a larger ported maf sensor is that it isnt as accurate at lower airflow anymore. For WOT that is obviosly not a problem for racing ect.. But most of us spend 99.9 % of the life of the vehicle running on the streets in everyday traffic and idling.. So, for drivability/ accuracy and mileage, ect.. The stock one with a screen in it is the best for that application. For guys with cams and large motors that want a car to run like stock again but have the power at the top needs every sensor to be super accurate.

BOTTLE ROCKET

iTrader: (4)

So would it be worth it for me to go back to a stock MAF (with screens) to regain some driveability and consistency, or would it basically be unnoticeable?

Ed Wright

iTrader: (1)

You are absolutley correct, but good luck selling them that one.

crewchef

iTrader: (6)

I had been chasing my tail on AFR issues for 6+ months w/ descreened MAF on my son's 88 GTA w/ LS1. Changed to stock MAF w/ screen, tuned w/ AFR % error and it's working like a champ. With descreened MAF I tuned it the same way but it was never consistent, especially at WOT. No dyno numbers but lost absolutely nothing off his ET in the 1/8th. It may have actually picked up some but can't be certain because I don't have DA written on slips for comparison.

If anyone wants a descreened MAF I have one I would sell

Ed Wright

iTrader: (1)

That screen doesn't just stop the bugs, it is also an air straightener. That is why it is so thick. GM didn't spend the money on those for nothing. I have also been preaching with a blown C6, if the non-screen factory MAF fails you should replace it with the truck version that has a screen. Turbulence from the blower often rattles those tiny wires loose. They live longer behind a blow-through style blower with a screen in place. After about 13 years most guys have finally stopped hacking the insides up, maybe they will eventually leave the screens in place.

BOTTLE ROCKET

iTrader: (4)

EW

If the screens are beneficial, (and I had heard the exact same thing about the screens actually "straightening" the air) then why did GM remove them from the Z06? (Which I think is where a lot of this comes from)

crewchef

iTrader: (6)

Not sure why they removed the screen but if you look at the two side by side you'll see that's not all that changed. I assume it was a total redesign when they took the screen out so working ok w/out the screen was part of the design.

I had to move my MAF on the Z06 when I installed the Callaway Honker and it changed my AFR (logging in open loop) a little bit but I was able to tune it right back to spot on.

moehorsepower

iTrader: (3)

Listen to the guys that know what they are talking about, not people who "Think" they know..Both are absolutely correct, As in previous post about a MAF, Speaking for myself I will not attempt to tune a car with a Ported MAF, Again on Stock MAF's, Mine, Bone stock MAF on a forced Inducted LT1, results 648 RWHP on Pump and 722 RWHP on Fast Gas, Air Fuel? Flat as a pancake, Driveability, Perfect.........
MoeHorsePower......

WheelmanWS6

Stock MAF. Love it, leave it alone, don't touch it.

From my experiences, no good comes from messing with the MAF. My old LT1 (car in the sig) was a turd. The thing never ran right after the cam swap, made crappy power, went through several mail order tunes, etc. Looking back, I think it was because I descreened the MAF and something happened....


I say this because,


My WS6 is making the power in sig. The first pull on the dyno during the tune, they shut it down mid-way through the run. They told me my MAF was dead and I was lean screamin. I knew the MAF was dying, and I had tried to clean it a few days earlier. They asked if I wanted to throw a new stock one on. I wasn't keen on spending $200 on an OEM, stock part that I could have upgraded.... Needless to say, I listen to the Speed Inc. guys and decided to stick with the stock MAF. And look at the results. Numbers speak for themselves. Plus the car is WAY more responsive, idles perfect, drives flawlessly, and is a beast at WOT.

I know everyone is tempted to cram the biggest, widest, least restricting metal-donut-of-a-MAF in there by hacking at it and trying to enlarge it, but its pointless. It serves a very particular and crucial purpose, so just leave the stock one alone.

Ed Wright

iTrader: (1)

If somebody calls about sending their PCM and when discussing their modifications they tell me have a ported (I have another name for that), aftermarket (won't post the name here, a sponser), or aftermarket MAF ends I simply tell them I can't help them unless they want to change back to a stock unit. If the vehicle is here, I have no problems re-scaling the MAF tables to corect for it. Just takes more time, for about a zero power increase. Through the mail, no way. Have had a couple indicate a stock MAF on my order form, to have them call back with something like 20% or so fuel trims. After further questioning I find they have aftermarket ends installed, but they still call it "stock". Guess they think the electronics is all that effects that. I've been preaching this since 1994, took a long time for some guys to believe it.

Frost

iTrader: (45)

+1 here

Gh0st

iTrader: (3)

That's amazing because I have ZERO issues with my descreened MAF. I redo my MAF tune every month or so just to see how it's doing and it's dead-on every time.

YellowToy/A

iTrader: (1)

It is a flow straightener not a screen. If the airflow thought the maf is good, it is not a problem to remove it. A flow straightener is used to make sure that the air is consistant across the pipe. All most all of use have made changes to the air intake track. An aftermarket lid make the air flow more consistant. That is why it adds power. After I took the staightener out I have looked at my air fuel ratio. It is good at idle. SO on a sample size of one, the low flow measuring of the MAF is OK. At full throttle my A/F ratio is very consistan. Again sample size of one, no flow straightener is required. I did see higher airflow with a ported MAF. Small gain but not bad for a 50$ part.

Here are the rules

1. Leave the stock maf alone unless you tune for the new one.
2 If you tune you may be able to port and take the flow straightener off.
3. You have to monitor air fuel and make sure that a/ ratio is consistant.
4. Take the MAF off for blown application, run SD.

IF YOU PORT AND TUNE YOU WILL SEE A POWER INCREASE FOR THIS 50$ mod.

Frost

iTrader: (45)

Back to back, same hour, same cars, same dyno, never even pulled the straps and swapped out MAFs on 2 cars and the difference was within 2 HP after getting the AFR back in line. That is inconclusive on a 400 rwhp car; something like around 1.2% and falls in line with repeatability to some extent. One of the 2 MAFs was a Granatelli and it was not consistent at WOT. The other was a MAF that had the center raped, I'm sorry, ported, and had aftermarket MAF ends. It appeared to pick up at first when getting the AFR pushed around for the sweet spot, but it became apparent that there was a bit of tail chasing very quickly.

On the other hand, I have tuned many MAF modded cars that were consistent, though they are not generally the ported variety. Most of those are 85mm truck MAFs and Z06 MAFs on f-bodies. The truck MAFs can be maxed out by a 450rwhp M6 car (DJ224 numbers).