Changing O2 Switchpoints to Match WB

[domestic rice]

Well here is 2 of my scans. The second one is with the stock switch points, the first one is with 150 added to the stock ones across the board. I looks like that might have made it run a little richer, now I am not sure if this is what I was actually looking for or not?

I realize that by making it run leaner, it will infact get me a better mpg. However I am worried that that will inturn make the computer add fuel, thus messing up my wot tuning. What do you guys think?

[5_Liter_Eater]

In the BWB log the average AFR is 14.76. The +150 log the average AFR is 14.60. I get this from making a bogus histo. Make the X axis of any histo some sensor (instead of a table) and don't give it any labels. Then use AFR for the plot value. So you have indeed made it a little richer. So if we do some mickey mouse math, 150 mV change got you .16 richer AFR so every ~9.4 mV 'should' get you .01 change in AFR assuming its linear, which it's not, again we're talking half assed math here. To make it easier and more half assed lets say -10 mV = +.01 AFR.

Personally I'd be pretty happy with an average closed loop AFR of 14.76. Right now you're at 14.6. If you want to try for a perfect 14.68 then subtract 80 mV to your current values and see what happens. Then verify that your fuel trims are in check.

Thinking about it for a little bit though lets revisit what you're trying to accomplish. Are you trying to push your push your stoich AFR around or are you trying to make your fuel trims jive with what you know is a perfect tune in open loop? See how your LTFTs are a lot higher in the +150 log? At first that makes sense because you're running richer but you're fooling the narrow bands O2's into thinking stoich is different than what they think it is so even though it's richer they should think it's still stoich.....

I'm getting myself confused. Try subtracting 80 mV and see what that does.

[ChrisV 02 - Z28]

What is the point of messing with the switchpoints? Are you trying to make your NB agree with the WB reading for CLOSED LOOP?

[5_Liter_Eater]

Correct.

[ChrisV 02 - Z28]

OK so when do you record the NB 02 mvolts vs airflow, I mean what mode are you in etc...OL, CL, OLSD, CLSD

I am also assuming you have to have your VE and MAF Table dialed in via WB beforehand???

[5_Liter_Eater]

You dial the VE and/or MAF with the WB first in open loop. Leave it in open loop and use the custom histogram which averages the narrow band mVs only when the WB is reads between 14.65 and 14.75. Plug the airflow modes and switchpoints into your tune and then re-enable closed loop and see if you're switching at ~14.7.

It should be noted that while this is in the gen 4 section, changing the switchpoints on a gen 4 PCM currently has no effect. Works well on gen 3's though.

[LazMan]

I still dream of them making this work in the next HPTuners update.

[SideStep]

Good Thread...

[onecamaro1]

What if you don't have a maf?

[PBMFIsMe]

Shouldn't make a difference if you dont have a MAF

This is a good thread. I noticed today after I re-enable closed loop that my narrowband O2's are switching at about 15.5 on the WB.

I think I'm just going to stick with OLSD and not bother with CLSD. Are the gains for changes in weather worth the trouble of making these changes to the switch points? If so, I may reconsider.

[onecamaro1]

I just tried this and i can see how it works........but.........Is this a classic example of "Kentucky Windage"? i rechecked my ve a couple of times and there were small changes each time. those small changes made the o2 mv change quite substantially. This means pick a VE and don't touch it after you set the o2 switchpoints. When you said spot on on the VE, you were not kidding. Good stuff though.

[BBA]

I think HPT needs to crack what ever code is necessary to allow me to adjust O2 switchpoints in my LS2...I definitely need to get closed loop over 15:1 just for mileage.

[LazMan]

Ive been doing open-loop again BBA ... this time on the MonteCarlo. It helps more than it ever did on the GTO ... im at around 15.8 at cruise RPM.

Interesting how this always comes back when gas prices surge. )

[5_Liter_Eater]

Well I've since swapped WB controllers and temporarily swapped sensors I'm pretty confident that there is nothing wrong with the WB so if the NB's want to switch @ ~15.5 thats fine with me as long as I know my WOT AFR is accurate. The last piece for me is to have my WB bung TIG'ed airtight as there are a few pinhole leaks.

[LazMan]

You've struggled with the uncertainty for a long time 5L ... glad you're finally sure that your OL tune is the right one.

Headers typically make stock sensors read lean. ... but you had no other way to prove it than to swap sensors.

Maybe we'll get this soon. I still dream.

[MMGT1]

This is what has screwed me for almost a year now. Tune with the wideband only to have the narrow say the tune is out by 3%! In a V6, as you guys know, if there is ANY fuel trim at all going into PE the vcm will carry it! PITA!!! Had to tune lower MAF with narrow to have proper fuel delivery in PE.

And Bill, wish you were closer to me, would TIG that up for you in a heartbeat for all the help you've given me!

[LazMan]

Yea, if you run long tubes, you pretty much have to run Open Loop and monitor the wide-band occasionally.

Some E67 tunes do the V6-carry-fueltrims thing (like my Monte Carlos SS) ... really a pain too.

[Jamz]

Anyone know if the latest Non-Beta Hp Tuners release has the switchpoint voltage vs airflow bank tables working or not? in the GEV IV L98 LS2 ECU's?

[FunkedOut]

I have found that the latest release of 2.24 still has no effect on my switch points; E38 2010 Camaro LS3.
Anyone have any luck adjusting switch points on a Gen4?
Is this a GM lockout?
Or an HPT 2.25 hopeful?
Thanks.

[Higgs Boson]

i never had any luck since my 01 Z06 with switchpoints doing anything. i just change the stoich table with the assumption the table is wrong (when wideband tuning is correct to lambda).