LS1b semi-closed loop operation question (B3647)

[RamAir]

EFILive has the LS1b has the B3647 Commanded Fuel/RPM,which when set to 14.63, will cause the ECU to go into a semi-closed loop state using the O2 sensors to keep idle and part throttle AFR @ 14.63.

If I want my idle and part throttle set to 14.1, then my O2 sensors will be ignored. How does the ECU command the AFR when in this state since the O2s are ignored? By the VE table?

Question: Is there a way to set B3647 to something like 14.1 and still have the O2 sensors ACTIVE?

[Happy Jim]

EFILive has the LS1b has the B3647 Commanded Fuel/RPM,which when set to 14.63, will cause the ECU to go into a semi-closed loop state using the O2 sensors to keep idle and part throttle AFR @ 14.63.

If I want my idle and part throttle set to 14.1, then my O2 sensors will be ignored. How does the ECU command the AFR when in this state since the O2s are ignored? By the VE table? Yes, that is correct

Question: Is there a way to set B3647 to something like 14.1 and still have the O2 sensors ACTIVE? No, even if you could then the O2 sensors would fight the 14.1 and move it back to stoich

Rgds

Jim

[RamAir]

Ok - another question: why would you want to SFTF Idle Disable (B4108)? Don't you want SFTF since the O2s are giving feedback?

[joecar]

Ok - another question: why would you want to SFTF Idle Disable (B4108)? Don't you want SFTF since the O2s are giving feedback?

Yes, you do want.

[RamAir]

That is what I thought, but in your documentation (pg 17 of COS using 2/3 bar) it indicates "several other STFT values may require adjustment:" {B4108} STFT Idle Disable. This value would either be on or off and your above statement indicates it should be on indicating I should not adjust. Confusing documentation.

[joecar]

You should try it both ways, just to see.

[Yellow05C6]

I'm using OS 12212156 (non-COS) and trying to turn off all fuel trims at idle. Clearly something is going on because (with a cold start) the engine idles well for several minutes then suddenly starts wild AFR fluctuations. This even though STFT & LTFT both indicate 0 adjustment. I cannot find B3647 in my tune file so I assume it is not in OS 12212156. But I think I understand the idea. So if I set B3601 to (for instance 14.5:1), do I avoid semi-open loop at idle? Or, do I also need to set the AFR #s in B3605 to something less than 14.68? If I do, will STFT / LTFT operate correctly when the throttle angle is above the max idle throttle angle?

[nonnieselman]

I'm using OS 12212156 (non-COS) and trying to turn off all fuel trims at idle. Clearly something is going on because (with a cold start) the engine idles well for several minutes then suddenly starts wild AFR fluctuations. This even though STFT & LTFT both indicate 0 adjustment. I cannot find B3647 in my tune file so I assume it is not in OS 12212156. But I think I understand the idea. So if I set B3601 to (for instance 14.5:1), do I avoid semi-open loop at idle? Or, do I also need to set the AFR #s in B3605 to something less than 14.68? If I do, will STFT / LTFT operate correctly when the throttle angle is above the max idle throttle angle?

B3647 is only in the COS's.
Start a new thread and post your tune.

[joecar]

+1 post your tune here.