OveRReV. Depends on the fuel but if you have 100% gasoline (no ethanol) in your tank then your target numbers will be 13.2 max power lean to 12.5 max power rich. For gasoline with 10% ethanol content (E10) your target numbers will be a bit richer, 12.7 max power lean to 12.0 max power rich. Next we need to account for the different ideal air fuel ratios of gasoline and E85. Ethanol has an ideal (stoichiometrically correct) air to fuel ratio of 9.0:1. Pump gasoline has an ideal (stoichiometrically correct) air to fuel ratio of 14.7:1. Here we will calculate the stoichiometrically correct air to fuel ratio for our blend. 9.00 * 0.83 Once identification of good and bad intake paths is made (either by airflow study, spark-plug readings, air/fuel ratio measurement or a comparable method), companion parts or tuning methods can be Fuel/Air EQ Ratio. = FAR / FAR (stoich) = AFR (stoich) / AFR. less than 1 is lean, 1 is stoich, greater than 1 is rich. Measured in units of Phi (ϕ) When describing fuel modifiers, F/A EQ ratio is easy to understand because, increasing the # increases the fuel delivery. An F/A EQ Ratio of 1.2 = 20% more fuel over stoich. after 3 passes N/A on a new motor i had a best et of 12.7 .with a A/F of 12.9:1 at 28 deg timing .jetted 50 shot and dropped to 12.1 et with a A/F of 11.9:1 , leaned it out by dropping fuel pressure and ran 11.7 et with a A/F ratio of 13.0:1 when i pulled or added timing et dropped so 28 deg was the ticket for that jetting . hope it helps. The ideal ratio is called stoichiometric, and it is defined as an air/fuel ratio of 14.68:1 (for gasoline), or Lambda equals 1.00. They both represent the same mixture ratio. The stoichiometric ratio is the control ratio for all modern electronically managed engines and the tuning standard for EFI calibration. E85 has a tuning window almost as wide as methanol, making tuning approximations almost as forgiving. However, the ethanol to gasoline ratio must be dealt with. Air/fuel adjustments for an 85-15 ratio will not work if the fuel is at a different ratio. Even if the exact ratio is known, the adjustments for fuel and air density changes can be complex. The computer looks at the air/fuel ratio from the O2 sensor and corrects the fuel delivery for any errors. This helps compensate for wear and tear and production variables. GM's Tuned Port Vay Tiền Nhanh Chỉ Cần Cmnd.

how to tune air fuel ratio