Closed loop?

[Robin Lawrence]

Best answer is "it depends". I have many cars running in closed loop that are very consistent. It also depends on the ECU. We have been told that ours corrects faster than many others. Our hardware and software guys say it also depends on how the code it written in addition to the speed of the ECU.

Alpha N is great on applications where you have a very large cam. Where there is little vacuum at idle and no resolution. Speed Density allows for baro changes. If running Alpha N you should have a baro offset table.

I run my stocker with a Combo program. It is Alpha N up t0 2000 RPM and 20% Throttle Position. After that it is in speed density. I typically see less than 2% correction in closed loop.

To answer the OP's question, as far as setting limits in closed loop. I would suggest 10% additive or + and limit the negative to 5%. As 02 sensors degrade from race fuel the 02 will tend to show lean thus adding fuel. I recommend installing new 02 sensors annually.

The ability to correct with little latency will depend on your combination. On dyno we can see very fast response at sweep rates 300 to 400 rpm per second. Most sporstman cars engines will accelerate in that range in higher gears making closed loop function very well. In Pro Stock the engine acceleration rates can be upwards of 2000 RPM in the lower gears. I did not recommend that they use closed loop. I had several teams that enabled closed loop only in 4th and 5th gear.

I don't enable closed loop in my Mustang until 6000 RPM. With almost no collector after the 02 sensor it doesn't give good information at low RPM.

Of course this is my opinion. Results may vary.

Robin