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how i can use the open/close loop feature from the SGII?? don't know why but it always stays on closed loop, even seconds from starting ICE. :mad::Banane15:

It lets you know if the ECU is in control of the fuel mixture/timing or if the engine is running on it's pre-programmed tables.

how i can use the open/close loop feature from the SGII?? don't know why but it always stays on closed loop, even seconds from starting ICE. :mad::Banane15:

You ask about how to use it. Well, the best way to use it is to try to stay in open-loop as much as possible. That is, by using deceleration fuel cut off when going downhill - if your car have it. SG will then show open loop.

Not necessarily Shrek. In closed loop mode your air/fuel ratio is around 14.7:1 which is the best for emissions. In open loop you could be running leaner, or richer than that. You should stay in closed loop for all accelerating and cruising. If you pop into open loop while your accelerating, your accelerating too aggressivly. However, like Shrek said, if you are decelerating in gear you will see it go to open loop because it is using dfco. Unless you are coasting to a stop sign and need to decelerate faster than just coasting, its usually better to pop it in neutral and cost, or fas.

It comes in quite handy if you aren't sure you have a problem. I noticed the ECU go into open loop a few times without throwing a code when I had flaky sensors in the Saturn. Open loop also tells you if you are accelerating so hard that the ECU is using default settings instead of making mix/timing calculations from sensor readings.

In closed loop the ECU is using sensor feedback to "optimize" mix/timing settings. Unfortunately, depending on who programmed your ECU, its optimum may not be the one you want.

Also, on Saturn's, they generally tend to run on the rich side(bad FE:() when in open loop.

Apparently the newer LAF sensors used for high performance tuning have a nifty feature for cars normally fitted with a narrow band...

They can "simulate" a narrow band output... but fix it at ANY A/F you choose.

14.7 too rich? Set it to 17:1 and your ECU will follow that instead. :D:D:D

They can "simulate" a narrow band output... but fix it at ANY A/F you choose.

14.7 too rich? Set it to 17:1 and your ECU will follow that instead. :D:D:D

That's what I'm counting on.;)

so open loop its th pre-prog and closed will be ecu controlling the a/f... so its better to stay in closed loop all the time...

I have a question. When I FAS and then bump start to continue on my way, my system goes back into Open Loop, regardless of the engine temperature or pedal pressure (TPS). It stays this way for more than a few seconds. I can only think that this is wasting some of my gas unexpectedly. I assume this is programmed to go for a number of seconds, until everything settles out, because the manufacturer did not anticipate FASing, and did this because most people start their cars once per trip, not continuously. Anyway, is there a way to get it back into Closed Loop quicker?

I have a question. When I FAS and then bump start to continue on my way, my system goes back into Open Loop, regardless of the engine temperature or pedal pressure (TPS). It stays this way for more than a few seconds. I can only think that this is wasting some of my gas unexpectedly. I assume this is programmed to go for a number of seconds, until everything settles out, because the manufacturer did not anticipate FASing, and did this because most people start their cars once per trip, not continuously. Anyway, is there a way to get it back into Closed Loop quicker?

I had the same thing happen in my Saturn. If I recall correctly, the FAS switch seems to have sped things up a bit? I would imagine that the Aveo and '99 SL2 have similar systems since they're both from GM.

Thanks for the tip, Diamond Larry. It's looking more and more like installing such a cutoff switch will be of benefit. My lights won't go off and back on, and my ecu will stay hot, so perhaps it will not switch to Open Loop when I bump start.