Airflow mode and O2 switchpoints.

[streetlegal]

Hello everyone! I havent posted in a while but I have a question. I have an 02 Z28 with an LS3 in it now and I have idle fueling nailed down where I like it and right at stoich with a wideband in open loop. It idles smooth as a sewing machine until I go close loop. In close loop the pcm pulls fuel out making it lope as if it has a cam. It has long tube headers and I would like to tune the O2 switchpoints but I can not figure out how to scan or log the airflow mode to see exactly where I need to change the switch points. I have read countless posts and learned a lot but I cant seem to figure this one out.
Can any of you steer me in the right direction?

[Ben Charles]

With a stock cam in that rig, it should idle no problem with the 02's around stoich.

[streetlegal]

With a stock cam in that rig, it should idle no problem with the 02's around stoich.

Oh it does fine till I go closed loop. I almost wish I would have gone with manifolds instead of headers this time around.

[Ben Charles]

You can keep it OL idle if you really want too. With a factory cam your probably idleing around 550 so set up the tune for OL below 800rpms. Works like a champ on cam cars I do.

[streetlegal]

You can keep it OL idle if you really want too. With a factory cam your probably idleing around 550 so set up the tune for OL below 800rpms. Works like a champ on cam cars I do.

It actually is in open loop at idle then closed loop above 1200 rpm. I just would prefer it to be in closed loop. When the wide band is reading at stoich, the NB O2 sensor voltages are around 800mv. The PCM pulls fuel and the idle gets rough. Ive never experimented with the switching voltages before. Most of my customers like the rough idle even though I know its not right.

[WS6FirebirdTA00]

Airflow mode is just a table that correlates airflow in g/sec to a constant. You can open the airflow mode table to set this up (basically use the g/sec in that airflow mode cell as your x-axis in a histogram).

Another thing you have to watch for is proportional fueling. It is not always the switch points but how the sensors are switching (or not switching at that). Too much proportional fueling could cause the sensor to rail rich or lean, where not enough could cause them to be flat (generally). Once you ensure you have good sensors and they are switching well, then you can work towards aligning the o2 switch points with the WB.

[streetlegal]

Airflow mode is just a table that correlates airflow in g/sec to a constant. You can open the airflow mode table to set this up (basically use the g/sec in that airflow mode cell as your x-axis in a histogram).

Another thing you have to watch for is proportional fueling. It is not always the switch points but how the sensors are switching (or not switching at that). Too much proportional fueling could cause the sensor to rail rich or lean, where not enough could cause them to be flat (generally). Once you ensure you have good sensors and they are switching well, then you can work towards aligning the o2 switch points with the WB.

So airflow mode isnt a table in the editor I thought I was overlooking, it would be a histogram in the scanner I have to set up. Well you wouldnt happen to have a "How to for dummys" on how to do that would you?

[5_Liter_Eater]

I played with it a while back.
http://www.hptuners.com/forum/showthread.php?t=11333

The thread was started for a different reason but it talks about setting up a histo to determine where the breakpoints for airflow modes should be set and what mv to switch them at. Come to find out it doesn't do anything on the 4th gens but if you want to play with it on the 3rd gens have at it.

[WS6FirebirdTA00]

It is a table in the editor.

[streetlegal]

Here is one of the tunes. Not the latest but the only one I have on this laptop. My dumbass cant find the airflow mode table.

[WS6FirebirdTA00]

Fuel>Open/Closed Loop>Mode vs. Airflow

[streetlegal]

Fuel>Open/Closed Loop>Mode vs. Airflow

All I see is O2 rich/lean vs airflow- Bank 1 and Bank 2. Click on on of those and I have O2 sensor B1 R/L vs Airflow Mode plotted in rich/lean O2 sensor voltages.
I see that but what is defined as airflow mode 0,2,4,6,8,10,12,14,16? Im thinking its the MAF table divided up into sections but how do you know where to divide it?

[WS6FirebirdTA00]

Left side of the tab (that I directed you to), bottom selection.

[streetlegal]

Left side of the tab (that I directed you to), bottom selection.

On the left side of that tab I have:
Open Loop
EQ Ratio.
STFT open Loop enable/disable.

Nothing else below that.

I have seen what you are referring to in a screen capture on this forum somewhere but I cant find it in anything I have tuned lately.

[WS6FirebirdTA00]

Should say general below that, what version of HPT are you using?

[streetlegal]

Should say general below that, what version of HPT are you using?

The latest beta. I had to get an upgrade a couple months ago to be able to tune a G8GT.

[c.u]

If you dont see this. Open the editor click on edit go to view and make sure you have advanced check.

[WS6FirebirdTA00]

Great point, I never used anything but so I forgot all about it.

[streetlegal]

Hmm. Ill give that a try when I get home.

[streetlegal]

DAM! I have a lot more things to mess up now. Thanks guys!
So are there any limits to adjusting these switch points?