Originally Posted by Hemlawk
Ahh thanks Bud. I'm a tuner-tard
So a CAI should bump it up to 12.5+?
Atleast these numbers aren't to far off from a New Mustang Gt...
No, the computer right now is basically telling it for X amount of air entering the engine, inject Y amount of fuel to create a certain A:F ratio. The O2 sensor lets it know where the mixture is.
The thing about it is that at WOT (Wide Open Throttle) the engine goes into what is known as Open Loop mode. This is because the O2 sensors that come on cars are really only accurate close to the 14.7:1 ratio. As it gets further away from that number, it becomes exponentially more inaccurate. This is why a good tuner uses a wide-band O2 sensor. Anyway,when this happens, the ECU stops taking readings from the O2 sensor and basically injects a pre-determined amount of fuel. Engineers from the factory tend to play it safe and tell it to inject more than what is needed. You don't want to run lean at WOT. It would take more than a CAI to cause it to run 12.5:1. A tune is definitely in order.