Whats up you guys. So i ran into a little problem and this is the first time it happened. Ive got a 2008 Sti Hatchback. Ive recently just installed a catted downpipe and cai running cobb 91 octane stage 2 tune. Today going 80mph the chack engine light went on. Does anyone know what i can do to figure out why its running lean? I also noticed while going WOT my A/F ratio is at 11.03.... Now is this on the tune or what? What else can it be? Im learning so be easy with me. Thanks!
11.03 a/f ratio isn't bad at WOT. Clean your maf sensor and look for any boost leaks. Were you crusing at 80 when it went lean or WOT? Do a log and post it here too to help see what's going on.
Were you looking at an external wideband to tell you AFR was 11.03:1? Or just the factory O2 sensor on an accessport? Did you actually read the CEL or are you just guessing? I would take it to someone who knows what they are doing.
Good luck with this. I've been chasing this code for months. Just replaced the rear O2 sensor, with no change. My error shows up during idle. everything seems to run just fine, nothing abnormal in the logs that I can see. I may have to take it in, but I am thinking it will be a large bill if they need to find some sort of vacuum leak.
This. Do you have a custom tune, or are you running the OTS (off the shelf) cobb map? The OTS maps are designed for the stock intake or cobb intake. A cold air intake DOES require a custom tune. A CAI will pull in cooler (and probably more) air, hence why you're running lean. Those engines are prone to ringland failure anyway, so running it in lean conditions is highly advised against.
I'm pretty sure that anytime you go WOT your AP is gonna just read 11 for your AFR. I wouldn't trust that value.
