Need some help with O2 sensors

[Always2Slow]

I am a bit confused here and looking for some guidance tried a few searches and couldn't come up with the information i am looking for. First i would like to know how i could tune the closed loop o2 sensor maps b4107 and b4105. What are a few maps i could make to log this information and make it relevant and my stoich afr is set at about 14.17 which makes things more confusing for me. I am using a NGK afx to log everything and looking off the gauge isn't accurate for me as its stoich is set to something like 14.53 or something from the manufacturer.

[spy2520]

Can you log lambda or eq instead of afr? If so that should negate the difference in the two different stoich settings. I could be wrong, but my theory was always that a wide band reads lambda and calculates afr based on the value you set as stoich or the stoich of the fuel.

For instance my wide band considers 14.7:1 stoich and the pcm is set to something slightly different. However a lambda reading of 1.0 still means 1.0 on both sides even though your gauge reads 14.53 and your pcm is looking for 14.17

[joecar]

+1 what spy said.

[joecar]

You want to tune B4105 and B4107...?!?

[Always2Slow]

Well yes i would like to tune the tables for more gas mileage i enabled lean cruise and seen great results with it so far and would like to lean things out a bit while just putting around town to help my gas mileage some more. Right now i have b4105 at 450 across the board and i would like to fine tune that for sure. I am using EQR for everything but wasnt sure how everything worked as in regards to my stoich value with making some sort of map for this because alot of people say to look at the afr.

[EagleMark]

.450 get's it centered on Stoich. I don't think trying to stray from that is a good idea. Just not accurate outside there and it's just a switch point. What I have done with other calibrations is find the 02 low and 02 high settings, usually .300 and .700 and bring them closer together to slow the switching. It sure smoothes out AFR or Lambda. Just have not seen those settings in definition?

There's lots of options in lean cruise {B3639} table.

HTH!

[Always2Slow]

Well i would like to tune for some more gas mileage while not in lean cruise for around town type of stuff i have seen people achieve results with high timing but thought there was a way that i seen reading to at least lean out the fuel while in closed loop.

[EagleMark]

I read here, a guy lowered the .450 to .3xx and gained some milage! He said it showed as running leaner on his wide band. I've never tested it so? It would be a very bad idea to even try without a WB because of NB inaccuracy outside of .450/Stoich

[Always2Slow]

I have a wideband to log everything but having trouble figuring out what to use for data column and row to log everything so i can see what my EQR is while driving around in closed loop. Anyone have some pointers on that one?

[EagleMark]

Just open a B0101 wideband map, then edit to your wide band PID and save as new name...

[Always2Slow]

Okay but whats the proper way to filter the data to only show closed loop operation?

[EagleMark]

SAE.ECT C exclude less than 80c should cover Closed Loop and engine warm.

[Always2Slow]

Now how can i filter or correlate that data to the differnt CL mode values or o2mv values?

[spy2520]

There is a thread somewhere on here that explains it. You have to create a calc pid for it, I believe.

[EagleMark]

I think doing this would really mess up data for tuning where having all .450 in all CL modes is a good idea.

But after you could raise and lower them depending on what you need for idle and what your trying to accomplish is cruise areas of CL Mode. Could work well as a lean cruise for OS without one, could cause to Lean a condition with Lean Cruise... not sure I'd want to tweak this and have lean cruise enable at same time... all theory at this point.

But thinking about this and how GM has changed O2 swing points over the years it may explain how they were trying to get a richer condition with ever changing fuel supplies?

First thing to do is know exactly what closed loop mode your in, this is linked to Scantool, but the 02 switch points are not. If you open your cal_link.txt file on approx line 174 you'll find Closed Loop Mode. Add this underneath to look like this:

;Closed Loop Mode
B4107.ROW=SAE.MAF,GM.MAF,GM.DYNAIR

;O2 Switch Points
B4105.ROW=SAE.MAF,GM.MAF,GM.DYNAIR

Save the file and reopen the Tunetool and play back a data log and you can see exactly what CL mode you are in. Change a CL mode from .450 .450 to .350 .350 and datalog to see how Wideband 02 AFR/Lambda reacts?

Remember leaner creates more heat then rich. Even if you look at lean cruise settings in a GM Factry Holden calibration it is not smooth, it will jump around from max lean to richer, leaner and never a steady state. I don't know if this is for cylinder/piston heat or Cat effeciency? Even very early GM lean cruise cals back in 80s and 90s had an on time off time... that said I've have run a TBI truck in lean cruise from 15.7 to 16.2 steady, no off time for 40K miles and no issues... 1990 Chevy Suburban 2wd and average 18.5 mpg highway, best ever was 19.2 mpg. 15 mpg is the worst I can do all in town in winter...

[Always2Slow]

I will find out my mileage on the way back home this weekend what i can get with lean cruise i just know i can do better than 450mv for switch points as they could use slight tweak as it just doesn't make sense that they should all be the same. My ide AFR jumps around right now even with a stoich of 14.17 ita like 14.1 for 1 second and the next 5 are 14.63 or so. My lean cruise so far is higher than 16 for sure but dont know the exact figure as thats what my wideband tops out at. My car basically likes two values when its cruising so i played with those thus far i just leaned them out a slight bit more around 14% lean at the moment should be fine still. I didnt know about the cal.txt file thing seems like that is a great source of information on what each map is composed of or how it is put together.