Originally Posted by synolimit

The tune doesn't matter. While idling or driving, a car will ALWAYS run 14.7 AFR. That's because it's in closed loop throttle. Only under WOT in open loop will you see AFR changes. What this actually means is if they did a sniffer test the car doesn't pollute over their EPA limits while at idle or while driving. Now if they didn't do a sniffer test then like ohio all they did was test the gas cap and check for check engine lights since check engine lights make cars run richer to protect then engine from damage. Richer obviously means lower than 14.7 AFR which is polluting more. Now if you had a huge fire breathing v8 and went catless and that engine was still idling at 14.7, it could fail since its feeding more cylinders and using more gas to idle therefore it could be over the EPA limits. Still don't know if you got sniffed but if you did its good to know a 3.7 v6 doesn't use that much gas in closed loop.