how lean is hacked 2nd gen mass????

[97gsssst]

The reason I ask is because I am running a b16g greddy-s bov and a supra tt fuel pump. And stock injectors 450s. At 17psi my autometer guage is reading pretty rich. I don't have an afc, but this guy told me to take out the 3 screens in the mas and back out the screw and it will lean me up to more torwards stoich. So I did and I am still rich. what do I need to do. Please help.

 

[green92gsx]

Taking the 3 screens out and backing out the screw should make you about 20% leaner. Don't trust o2 readouts for fuel,you need some sort of logging tool to know for sure. The supra pump without a adjustable fuel pressure regualor could make the car run richer.

 

[97gsssst]

what does the o2 readouts read correctly lean or rich.

 

[CanadianTSi]

what does the o2 readouts read correctly lean or rich.

neither, it's just a guess.

 

[16g-95gsx]

Understand this, hacking a MAS doesnt just give a linear error in the reading on the mas. The error is based off of the velocity of the air traveling through the MAS itself. During idle and extremely low airflow conditions, the air is traveling much slower and therefore has a much longer time to change its direction and travel down the less restrictive portions of the meter where it will be unmetered, however during cruise and WOT it will be traveling much quicker and there will be a smaller error due to the fact the air doesnt have the same amount of time to change directions and become unmetered. The calibration actually looks somewhat like a decaying exponential curve as far as calibration goes.

 

[Cirus_93TSI]

for starters, your blinky air/fuel guage is not much more then a pretty flashing light. the difference between running too rich and to lean on that guage, is 1 green light. that guage reads from .1 to .98 volts, all real tuning is done between .88 and .96, which are the top 2 green bars. unless you have checked the air/fuel ratio on a wideband, chances are your not running lean.

secondly, do yourself a favor, and dont hack a 2g mas up. it supports a good ammount of power, and if your really making too much for it, get a maf translator and a 3" MAS. hacking a 1g mas may be a good idea, but for a 2g unit its not.

and if you dont have an AFC, you have absolutly no chance of the car running good with the MAS hacked.
i had a hacked p 2g mas in my 91, and it was the worst mod iv ever had on any of my cars. the settings at idle are terrible, the airflow readings are extremely wrong at idle and low rpm cruising when you hack it. you will need to add a ton of fuel at idle and low rpm for it to run right, i had 550s and my setting at idle was like +27 to keep the low fuel trim from pegging at the max of 139. but higher rpm low map, and high map settings were like +5(the 2g mas in a 1g basicaly cancles out the extra fuel from the 550s, so settings will still be similar to this on a 2g)

the side honeycombs were still in the mas, and it was still that bad on airflow readings. a fully hacked one is much worse. and ontop of that, fuel trims were off at least once a week when i got in the car. conditions outside were different, and sometimes the low trim falls into the low 90s, and other times it burys at 139% and i have to re-tune it.

its your dsm, and you can try this if you like, but IMO the guy who told you that didnt know very much about your car, and gave you bad advice. im just trying to save you the trouble of hacking your mas only to find you car runs terrible afterwards, and you need to put the honeycombs back in. even if you had an afc to compensate for the extra air, its still not worth it to hack a 2g mas. i tried it, and i will never do it again.

 

[B005T3DT5i]

i think the A/F gauges with the bouncing light are crap....very unaccuarate....

 

[RoasT BeeF]

I agree. Dont remove the honeycombs from a 2g mas. They are there for a reason. The screw backed out flush will be enough anyway.

 

[Turbo Monk3y]

hehe i dont know much about the 1g using the 2g mas, but i do know that my brother has a 1g TSI AWD and used my old MAS out of my 2g... He had a 255 fuel pump and turned the boost up to 16 and it spiked to 17 maybe 18psi and he put a dime sized hole in #2 piston :laugh: so i guess the answer to the original question is that it puts in ALOT more air then the stock 1g one hehe...

 

[Cirus_93TSI]

a 2g mas(unhacked) flows 20% more air then a 1g mas at the same karman reading. so if you put a 2g mas in a stock 1g, it runs very very lean. if you put a 2g mas and 550cc injectors in a 1g, it is driveable because they almost cancel each other out. it would still need alot of fine tuning, but it would run.

1g mas dont flow that good, so its a common mod for a 1g to have a 2g mas. but you need an afc to compensate, your gonna blow your engine without an afc with that mod.
hacing a 2g mas with no fuel control would probally produce a similar ammount of lean-ness.

 

[97gsssst]

what if I am running a supratt fuel pump? Then could I somewhat hack the mas?

 

[97gsssst]

well I took out the two side screens in the mas and I run lean at wot from 4k to about 5k or so then it comes to normal but the higher the rpm the richer it gets could this be I need to hotwire the pump or should I just throw the screens back in and run pig rich? until I can afford an afc?

 

[ACKERSON]

I don't think you are running as rich as you think you are with the unhacked mas. You need a logger, everything that cirus93tsi is correct. You don't need to hakc your mas. I had a hacked 2g mas on my car and it idled very poorly and it was harder to tune. Save your cash for the logger/safc setup or dsmlink.

 

[green92gsx]

I pulled my side honeycombs out because my unhacked mass started dropping counts around 2400hz. Other than that my car idles fine with no stalling problems or anything.

 

[diambo4life]

I pulled my side honeycombs out because my unhacked mass started dropping counts around 2400hz. Other than that my car idles fine with no stalling problems or anything.

That's odd. I would think by removing the honey combs, you would "drop" the Hz count and not the other way round. Unless I'm not really understanding your statement. You do get a higher Hz count with all the honeycombs in. That's the whole idea of taking them out to drop the count especially if you are flowing alot of air (with a bigger turbo) and trying to distance yourself from fuel cut.

 

[green92gsx]

I'm sorry I ment to say missing counts.
Yes my hz count did drop from 2400 to 2100 after removing the honeycombs.
Thanks for pointing that out diambo.

 

[Cirus_93TSI]

well I took out the two side screens in the mas and I run lean at wot from 4k to about 5k or so then it comes to normal but the higher the rpm the richer it gets could this be I need to hotwire the pump or should I just throw the screens back in and run pig rich? until I can afford an afc?

the amount of fuel the pump is supplying isnt the problem. what is, is that without the side honeycombs, the airflow readings are not consistant through the rpm range anymore. without the honeycombs, you run much leaner at low airflow then at high airflow. the only way your going to get it tuned where you want it with the honeycombs hacked, is if you use fuel control to compensate in the specific rpm range that you need it.
thats why we keep saying not to hack your mas, if you somehow add more fuel through the whole rpm range, and richen up the rmp that is lean, the entire rest of the rpm range will be richer as well. you need an afc or some type of fuel control for it to run right.