Originally Posted by chadnky
I have a 2005 Chevy Cobalt SS/SC and today the engine light came on so I took it to autozone to see what code it was throwing and it was the P0171. My car has been making this funny noise like the sound of an exhaust leak when I accelerate. The noise started a few days after I took my car in for an oil change about a month ago at Valvoline. When I got home today I popped my hood to find that my air duct going to my supercharger has been loose for over a month so I tightened it and it still makes the noise like it has an exhaust leak. There is a stage 2 done to my car with the bigger injectors and smaller pulley, however, everything else is factory except the clutch which I wouldn't think would cause a problem. Could this loose air duct have messed something up?
Check your air duct again, maybe it has a hole in it, Also check the hose that goes between your air duct and the back of the engine for holse. Check your vacume lines for holes leaks.
P0171 = System Too Lean,
If your not modded, it means that your getting more air in your intake, the what the MAF (Air flow sensor) is sensing, so its makeing you run lean (Not enough fuel for proper combustion)
I say keep checking your lines/hoses and espessly your intake ducting for leaks. Take out a section if you have to (if you have the stock intake) Check where the intake goes down behind the headlight for leaks, and check where the intake goes in front of your PCM for leaks. Look arround while the engine is idleing see if you can find / hear the leak that way.