custom 68

iTrader: (8)

do you ever run closed loop? Maybe different tunes? I am in the process of dialing in my 2 bar system and thought once I had the VE tables good I would turn back on the closed loop for the LTFT and STFT.
Maybe most people just dont use the O2 sensors.

Atomic

iTrader: (42)

I always run closed loop, but dont bother with LTFTs because they can interfere with open look fueling, so I just run STFTs. If your VE table is close enough you shouldnt need the LTFTs anyway. I tune close loop with the o2 sensors, and open loop PE fueling with the wideband. I trust the 2 narrowbands at stoich more than the wideband at stoich (closed loop), although in theory they are the same, I would rather have 2 sensors telling me its correct instead of just 1.

nonnieselman

iTrader: (10)

That was just the easiest way i found out how to do it..

Ferocity02

iTrader: (59)

Let me step back a bit. How is the fueling determined in open vs. closed loop? Open loop only happens when the engine isn't up to temp, correct?

GMCtrk

iTrader: (27)

Lean cruise is activated by a patch which enables the factory lean cruise tables like holden cars have. I would not let lean cruise have any bearing on your software choice as the mpg gains are minimal to none in my experience. With very aggressive dfco settings i was able to gain ~1-1.5 mpg but i hate the feel so i turned dfco off

Atomic

iTrader: (42)

Yes, and when under load. You can set the enable temperature high, so the computer never thinks its warmed up and stays in open loop.

Ferocity02

iTrader: (59)

So how is fueling determined in open vs. closed loop?

Downsides to running on open loop only?

Atomic

iTrader: (42)

Based on the commanded equivalence ratio and ve table or maf table. There is no feedback from the o2s to correct any fueling errors

Ferocity02

iTrader: (59)

So are the O2's only capable of monitoring AFR's around stoich? Can closed loop only be used to maintain stoich, and not anything higher like in lean cruise?

I really appreciate all of the help! The pieces are starting to come together.

custom 68

iTrader: (8)

I am learning on this too but yes the o2s are only able to work around stoich. When they are active in closed loop they will oscilate. When you go into PE they are not utizied but I have seen a chart that shows a corresponding value for rich or lean but again this is only a quick reference.
What I understand if you run in open loop it uses the VE and MAF tables and does not get any feedback from the exhaust if it goes lean or rich it will not try to "fix" it back to stoich. All that said if you choose to ignore the o2 sensors and dont set any LTFT or STFT you can lean the area of cruise out some. I am not sure of the advantage or disadvantage of either way, I was going to tune my VE table and turn the fuel trim back on. Maybe others will chime in. I thought we would want some feedback from the sensors.