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Originally Posted by Fire and Ice  To answer this question: GM programs predetermined values for A/F ratios in that the vehicle must abide by. As a perfect example, when we've taken the STS-Vs in for tuning, the PCM is, from the factory, programmed to a target a/f ratio of 10.5:1. This means the PCM is constantly trying to achieve 10.5:1 a/f ratios regardless of the amount of air you introduce. It doesn't matter if you have a cold air intake or not, the vehicle's computer is STILL trying to produce that air/fuel ratio.
Now things 'might' be different on your CTS-V, Chris, but this is not a CTS-V, it's an STS-V and this vehicle has different parameters set for it. Number one, being a supercharged vehicle, the a/f ratios are typically run a lot richer than your CTS-V, unless you added a supercharger. Ideal a/f ratios that produce the most power reliably for the STS-V is around 11.7:1. A naturally aspirated motor can be run a lot leaner without worry.
Getting back to the first paragraph, if the STS-V is set to target a 10.5:1 a/f ratio and we tune the vehicle to instead target 11.7:1, of course we're going to get an increase in power and torque. Is it worth tuning? You bet! Ask any of the STS-V owners if they feel a noticeable difference after a performance tune or ECU box install. I hope this clarifies things a bit for you. |
Most of what you said there is completely moot.
The factory tune is configured to work with the factory hardware. Once you modify that, it looses some of it's ability to modify the A/F ratio. It might still think it's at whatever it thinks is ideal (10.5 for oyur STS-V as you indicate), when in reality, it will be higher. Once the LTFT's settle in, it will come back down a bit, but it will still be a bit higher than it was when it was stock. When you add a CAI, it will allow more air into the engine. The MAF still thinks the same amount is comming in to some extent (because it was calibrater with the stock air bridge and stock filter, etc.) When you first put it on it will run a bit lean untill the LTFT's catch up, and richen it up some.
I'm not sure where you guys are comming from with this stuff, this is basic car modding 101. Add a CAI, and you car will run a bit leaner. Add headers, and it will run a bit richer. This is true untill you get a tune.
Untill I see RWHP dyno results backed up with A/F from a wideband, done once the LTFT's have settled down, I will take your results with a big grain of salt.
Finally, I am a proponenet of CAI's. I think they are worthwile mod. The end user is going to have to determine if they think paying somewhere between $22.50 (D3's claim), and $45 (my estimate) per HP is worth it to them.
For the record my LPE cai is at about $31/hp, while it was advertised at $12.50 / hp. I mainly did this because I knew I was going to mod my car more, and eventually need the extra airflow.
For the guys who won't do any mods beyond this, they are going to have to decide if the added sound that this mod brings to the table is worth it or not, because by itself it's not going to do much.
-Chris