nickkleman

just a question, i have a 2006 cobalt ss/sc, i already have 60# injectors with a zzp 1.0 pcm tuned for the injectors and my ls4 throttle body, I'm going from a 3.1 pulley to a 2.7, would i need to get a tune, or would i be good since I'm already tunes for they injectors.

nickkleman

Anyone?

Olybaltss

I would say it's gonna be a stretch; you'll be pulling in more air than the ECU is programmed to push fuel for. I'm not a pro, but i would think it would run too lean jumping that much of a pulley size.

In other words, I'm hoping my opinion/bump helps you get the answer you're looking for

nickkleman

Thank you for the reply, I guess I will just put it on and see, worst scenario is it will run lean and I'll just lay off the boost until I get a new tune

07blackg5

iTrader: (8)

that is a huge jump. Wait until you get a tune

nickkleman

But I already have 60# injectors with a tune for it, which is capable of enough fuel, wouldn't the maf catch how much air is going in and just dump fore fuel?

roadrage06

You're MAF has to be told what to do when it experiences that much air. I'm no tuner, but I'm guessing it's not as simple as your MAF just requesting more fuel or we'd never need tuning, just the parts to handle the request from the ECU.

Don't be a cheap ricer; get the tune.

nickkleman

I'm putting the pulley on today and I'm going to put it on the dyno tomorrow and see what air fuel I'm at

roadrage06

That's a smart start. AFR will definitely let you know if you need a tune.

Olybaltss

IF you don't have a way to monitor AFR right now, i'd look at grabbing an ELM327 OBD2 bluetooth dongle; you can sync to your (Android) phone, and get just about any sensor/data related information from your car you want through a few different apps, TORQUE being the best. that way you can monitor everything safely until and after it's tuned.

nickkleman

I have the torque app. UT I can't find the air fuel ratio anywhere

07blackg5

iTrader: (8)

because it isnt there

07blackg5

iTrader: (8)

are you on e85, and is your only cooling mod the extra heat exchanger?

nickkleman

No, pump gas and yes, I have it running through the stock he then the stage 3 front mount and a high flow pump

07blackg5

iTrader: (8)

You should probably look into a dual pass, and probably an option B before you drop to a 2.7