Another S/C'd member worried about his AFR

[Loren]

Without taking the time to read through this whole thread... some thoughts.

What does "open loop" mean? It simply means "not closed loop". Closed loop means that the ECU is using feedback from the O2 sensor to fine tune the fuel mixture and keep it at stoich (or, I suspect maybe even a tad lean on the Yaris, but that's just a guess). In open loop, the ECU is most definitely still making adjustments and still has complete control of timing and fuel, it's just ignoring the O2 input and using intake air temp (temp affects density, a critical factor), air flow, and RPM to look up the appropriate fueling and timing in a table. By design, this will always be a rich mixture, and timing will be "conservative", similar to that of a distributor with no vacuum advance.

Now, I was thinking about all of this worry about being lean on these SC cars. (because I noticed one for sale for $2500 and had a fleeting moment where I was thinking about it... until I remembered that I don't have the money) Remember, even though your car is "forced induction" with the SC kit, it's a VERY light boost. What is it? 4psi? Maybe 6psi? Guess what? The real problems with fuel and spark retard don't happen until way beyond there. You guys are applying the kind of fear that one should have with a medium-high boost turbo to a low-boost supercharger, and I really don't think it's warranted at all.

I'd rock a Blitz SC right out of the box. Run premium fuel and be happy. Life is too short for such paranoia!