Understanding AFR's
 

I know 14:7.1 is perfect. I am trying to learn/understand what the lower numbers or higher numbers mean. I had my car dynoed on Saturday and my AFR is way off! I guess cruising ratio is 15:5.1 to 16 and then it drops to 8.9? I just had a mail in reflash, drove the car and it didn't feel right, that's why I went to the dyno and put down a whopping 178whp and 230 torque. I talked to Al and he said send it back but it doesn't sound like the reflash. I am just a noobie lost in Kansas :).

The ratio is parts Air : parts gasoline. 14.7:1 is 14.7 parts Air to 1 part gasoline... The higher the ratio (15.5:1 for example), the LEANER the mixture, i.e. more air. A lower number means your mixture is RICH (i.e. 10:1), which is safer for the motor. How are you measuring AFR for cruising? did you get the 8.9:1 from the AF reading on the dyno? Sounds like she's rich under load.

8.9 is like Bill Gates rich!

Yeah, she is really rich! I was driving behind it on Sunday and she let out some serious black smoke. The AFR was measured on the dyno.

holy crap! 8.9 AFR?
You better get that fixed.