In Tuner Cat under the PE % Change to Fuel/Air Ratio vs Rpm screen, when you increase the value does the AFR go up meaning more fuel when in PE(numericaly lower AFR) or is it the opposite of what I described. I want to give it more fuel when I envoke PE.

Thanks Tom

 

It means "more fuel added" and thus it will lower your AF ratio as you have "more fuel to air".

On some of those, you can actually put a "negative sign" which means "less fuel" and it leans the mixture.

 

Air:Fuel

12:1 . . . Rich . . . 12 parts air vs. 1 part fuel

13:1

14:1

15:1

16:1 . . . Lean . . . 16 parts air vs. 1 part fuel

From what I've seen posted a lot of people are seeing peak hp at a AFR that is richer than the 14.7:1 that we tune for in our PROMs - correct?

 

That is correct. 14.7 to 1 is stoich supposingly best fuel economy and I believe keeps the convertor happy.For wot the goal is generally 12.8 or lower depending on what combo you have.

 

14.7 is just best chemically.

It has nothing to do with what makes the engine happy or gets best mileage or peak HP. That all varies by engine.

Richer then the 14.7 is used for in cylinder cooling, ie to prevent detonation. Again varies by engine, can be anything from 13:1 to 10ish:1.

They toggle the AFR across 14.7 to keep the converter working. The engine doesn't target 14.7 it targets averaging it, with swings richer and leaner then 14.7.

Long stories made short.