CbYellowSS

alright my mods are

gm stage 2
injen cai
cti header and downpipe
corsa touring exaust

i have noticed while showing off my car that i am blowing black smoke so im guessing im running rich

i wont be getting hp tuners for atleast a month up 2 3 months so i was wondering if i slapped on a 2.8 pulley for now would that help lean out my fuel a bit???

and if i just let it run rich it will damage my car correct??

all help is appreciated

SuperCobaltSS

Im havin the same isued except i have a 2.8 pulley was wondering if i went to a 2.7 would i be better??

PlaysWitCars

I ran really rich on the dyno which made my hp drop off after like 4500. Im running 2.8 with 42.5lb injectors with maf-t, cai, header, dp, catback

carbombss

im havin same prob

CbYellowSS

well looks like ill get a 2.8 for now and see how that will do

Bad06SS

iTrader: (1)

I would be careful. Rob just tuned a GM stage 2 car with a 2.8" pulley this morning. With the 42.5lb injectors and the 2.8" pulley, the Injector Duty Cycle was 115%! So, me personally, I wouldn't drop to a 2.8" untill you have the ability to be tuned properly (HP Tuners), a wideband (or on a dyno), and some 60lb injectors. You take a risk at hurting your motor by dropping a pulley without knowing what your AFR is. Just a thought.

CbYellowSS

well isnt me running rich and blowing black smoke now hurting my car???

and if i did get a 2.8 from zzp i would need that a puller and would i need a tensioner??

glockglade

There is NO way your injectors would be running at 115% with a 2.8 and 42pounders I am running 11.5 - 12.3 at WOT there are people on here reporting 110% duty with a 2.7. with just the gm tune which runs the injectors if I am correct at around 80% with a 3" pulley and around 95% with a 2.8. Running too rich won't hurt the car as much as running too lean however you should have an a/f meter for at least the dyno to see where you are before and after. Also make sure to disconnect the battery so the computer will learn your new mods.

Bad06SS

iTrader: (1)

First of all, that almost sounds like you're calling me a liar. 2cnd of all, you should be smart enough to know that each car is different. Maybe the person that Rob tuned that was 115% has more bolt-ons and is moving more air. Or did you ever stop and think with the different weather, elevation, and temperatures that results could be different? Last I checked for this time of year going into winter that it gets colder hear than it does where you're at in Palm Beach. Colder air is more dense and requires more fuel. So please don't base everyone else's car off of your specific results.

LandonElf

Question, did he have an aftermarket CAI setup? And are you using the stage 2 belt with the 2.8 pulley? And how hard is the 2.8 install on a GMPP stage 2 cobalt.

Sorry for all the questions, but i'm on a need to know basis.

Bad06SS

iTrader: (1)

Not sure if he had an intake. I would imagine he's using the stage belt since he bought the stage kit from GM. The 2.8" should be cake if you're using a pulley that bolts to the GM hub.

cds00bsmg

All of the different opinions on Injector duty cycle and pulley sizes seriously concern me. It just further confirms that I will need a wideband to monitor my AFRs when I start upgrading beyond the point I am at now....

glockglade

Not calling you a liar it just must be damn cold up there then .the car is pretty much the same i/h/e and the stage kit but i'm not trying to argue just helping out. If he's running at 115% that is definately not safe. Just get an a/f meter. If you set the a/f correctly on the dyno then you won't need an a/f meter after as long as your mods stay the same and the temps don't change more than usual.

beamSS

it's me! rob nice guy. ill be back there when i get my 60#. Thanks rob

beamSS

temps were around 60-70 when we did it.

Bad06SS

iTrader: (1)

No problem man, and my point isn't to prove who's right and who's wrong, my point is that you just have to scan your car to see what it's doing. That's why I told him not to drop to a 2.8" without a scan tool and HP Tuners (preferrably with a wideband) to be safe. We're all here to help each other.

Alex47

to rich = safe
to lean = BOOM!!!!!!!

ludicristSS

Why don't you come to the UPS show and I'll fix that for you .

Do not just throw a pulley on your car you will hurt it .You should get your A/F and we can advise you the correct way . Just a heads up the 2.7 with 42lbs will run out of injector over 6600 so for you guys running this combo shift at 6600 or you'll have a problem sooner or later

BTW there is no happy median with the MAF-T your either rich or lean and mostly both at different RPM's !
Guys get a tune even if it's mail order .

ludicristSS

Come to the UPS show in laurel . We'll fix that .