buy adding aheader and down pipe, that will help lean out the gm stage 2 tune? am i right.. I know the only way to really do it is to get a proper tune, but that option is not avaialble at this time..

i heard this from another memeber is this true?

 

i don't think it'll lean it out... the computer will compensate for it (i think)

 

by doing some ricer math i appear to be running less rich now that it's starting to warm up. over the cold winter months, i would clean my exhaust tip and after 3 minutes of driving it looked like i never cleaned it once. now that it's a little warmer, the finger mark i swiped across it is still there after about 3 weeks.

i could be wrong, because i don't know much about tuning and the gm stage tunes, but i've asked around and the impressions that I got is that the tune won't lean out untill you're maxing out your injectors and they can't keep up, which is pretty much at the top of the gears.

 

2.9 Pully will lean out the GM stg 2.... That and an Intake. Other wise.... nothing

 

well, i am running gm stage 2, injen intake, and have my zzp short header and 3 inch dowpipe with high flow cat going on today,...

 

Throw on a 2.9 and you'd be in really good shape. As far as leaning it out with the header and d/p, No I don't belive it would lean it out at all....

In order to lean it out, you'd have to have more Air going into the motor, or less gas going in.... So a H,d/p would do either of the 2....

 

well in a way it will help lean out the curve at higher rpms though??

 

To an extent, only after your injectors can no longer keep up.

 

thread jacker/ ive been running stage 2 setup on my stock tune, not a very good idea but im getting tuned tomorrow

 

lol, yea, not a very good Idea at all.





Then again if ya have't blown up, more powa to ya!

 

haha ive only been driving it since monday and im getting wicked tuned tomorrow

 

Wrong, doesnt matter what pulley you slap on the ecu will compensate for the targeted a/f ratio programmed in, so you could run a 2.6" pulley on a stage 2 tune and it would still run super rich, but this will kill the injectors becuase they will be way over 100% injector duty cycle. The only way to lean it out is to tune it or slap a larger ls4 throttle body on it

 

Oh, thats not bad. I thought U had been driving it for a while. lol

 

haha no thank god, i cant drive it hard which sucks, i did take it up to redline in 2nd and got 15psi but it started to bog right at redline (6.5)

 

people need to stop misinforming people on the internet im tired of going behind people and telling them that A PULLY SIZE CANNOT CHANGE YOUR A/F ONLY WAY TO CHANGE YOUR AIR FUEL IS BY TUNING YOUR CAR .

 

so by swapping a smaller pully and maxing out your injectors, you're not affecting your a/f? if you're that upset about it give more complete answers. swapping a pully can and will make your car run lean depending on the size.

 

waiting for explanation from Mr Smarty pants over here...........

 

I have the GM Stage 3 pulley on mine with an intake. It seems to have leaned it out a little bit, because I don't get the stage 2 hiccups like I used too. I put some colder plugs in too and that helped also.

 

I think you're right, my car ran pig rich in the winter time

 

The ECU commands the amount of fuel delivered based off of airflow. So just as an example the stage 2 configuration commands let's say a 10:1 AFR at WOT (it's actually not that far off from that in some areas) from 2500 rpm all the way to rev limit. By changing to a smaller pulley you will increase airflow where the ECU will still be commanding that same 10:1 AFR. The only way that a smaller pulley will affect your AFR is if the MAF values for those higher airflows are skewed from what you would normally be seeing which would cause fueling changes. If i remember correctly the stage 2 delivers a pretty linear fuel curve for really any airflow value when the RPM is above 4400.

When going from my stage 2 pulley to the 2.8 I will make no changes in fueling if using Stage 2 as the base tune.... I change timing slightly but that's about it and unless the injectors simply cannot keep up the AFR will remain the same.

 

you can change as much as you want.

but if you dont change your tune, your car will still try to run the same AFR as it did before you modded.


The theory that pullying down, or adding intakes/exhaust will lean you out is a myth.

 

again, unless you're maxing out your injectors. everyone keeps leaving that part out.

 

i just posted in another thread about this, but with the mods i have i'm seeing 11.3-11.8 AFR on stage 2 tune. There are ways to lean it out, but the pulley is not one of them. I'm not sure which mods for sure help, but i believe a 3" intake since it slightly tricks the MAF and supercharger porting and cooling mods which allow for denser air charge to get into the cylinders. Headers and exhaust may possibly also help a little to keep the air flowing as much as possible, i have long tubes w/o a cat and 3" catback.

mainly your computer is going to be using a combination of the MAF, MAP and o2 sensors to figure out the air coming through the system and deliver the stage 2 commanded fuel for that air with or without mods.

Leaning it out or not, header and downpipe is a good way to make some beastly power, the exhaust manifold is one of the most restrictive parts of the cars system with the intake manifold probably coming in second place for restriction amount and dowpipe at a late 3rd. Believe it or not, the intake and tubing is one of the least restrictive parts on these cars.

 

maxing out your injectors is not what i would call "leaning out" that suggests some control to what you are doing.

thats what id call.....poor modifying.

 

exactly