Closed Loop Mode vs Airflow Table

[Billiumss]

Under the OL & CL tab, on the right there is a Box that is the Closed Loop Mode vs Airflow Table.

I might have asked about this table before, not sure though.

Can someone give a good explaination of what this table does and what the numbers/values mean. It seems other tables reference it and want to learn more about it.

[S2H]

well...
I dont have a scientific explination as per GM and what its intended meaning is...
but...

if you think of it like your Fuel Trim Cells..only its Airflow Cells...then that helps some..

its used in conjunction with your O2 voltage switchpoints table
it does a compare of the values in the cells and looks up a value in the o2 tables and works to get the vehicle to have the proper fueling to switch around the appropriate voltage

I made this excel worksheet to help mysoelf out with tuning o2 switch points

I'm not gonna explain it cause Its not somehing I want to type out right now...

I ended up translating this into a custom histogram that only I understand how to use in HPT to tune O2 switchpoints after I have done the VE with my wideband....
unfortunately there no way to get a PID for the airflow mode...
so that means I had to redo my airflow modes table so that it made sense for a histogram...

the airflow modes table is in Grams/Second
and its based off of the Dynamic Airflow PID
I make sure everything fits a 0,2,4,6,8,10,12,14,16 airflow mode in that table so that I can make it fit my custom histo I made to do O2 swichpoints



thats as far as I can get ya...
and my method works perfect for tuning o2 swicthpoints
I'm not giving away my secrets completely just yet though

[Billiumss]

I understand it some, so basically this could help for lazy O2s and more accurate fueling in the lower RPM band?

[S2H]

I understand it some, so basically this could help for lazy O2s and more accurate fueling in the lower RPM band?

a lazy o2 is one that is not switching properly cause its not getting hot enough to maintain a proper operating temp...

its more like correcting the offset so that narrowbands properly match your wideband that you know is accurate

[eficalibrator]

Scott, may I ask why you need to change HEGO switchpoints? Are you seeing significant (greater than 3-5%) changes compared to the wideband (what wideband are you using for reference here?) that warrant a shift in switchpoint?

I totally agree that it's common for cars with large cams and longtube headers to have issues maintaining HEGO temperature at low speed/loads. This alone can lead to some misleading data when one tries to correct based on narrowband feedback.

[S2H]

Scott, may I ask why you need to change HEGO switchpoints? Are you seeing significant (greater than 3-5%) changes compared to the wideband (what wideband are you using for reference here?) that warrant a shift in switchpoint?

I totally agree that it's common for cars with large cams and longtube headers to have issues maintaining HEGO temperature at low speed/loads. This alone can lead to some misleading data when one tries to correct based on narrowband feedback.

as far as a wideband goes I own an LC1 and I have used just everything else thansk to many friends that needed some help and bought their own widebands and HPT to use

as any engine specialist should know...(not all do)
O2 placement for a narrow band o2 is fairly critical...too hot or too cold and the o2 sensor will no longer read accurately...its designed to operate in a specific heat range and when theat gets off then the stoich switchpoint voltage also changes
at different rpm and airflow ranges the amount of heat changes so this is the main reason for having an o2 switchpoint table to begin with...
if you use a wideband o2 which is much more accurate and more tolerant to a wide variety of temperatures then you can correctly calibrate the existing o2's to match what we believe is corect according to our widebands

this is half the reaon why there are 100's of differnt varieties of narrowband o2's...because they were designed to meet different heat ranges and work more accurately when your engine and exhaust produce that specific amount of heat....

and ANY mod can alter that heat range that the engine produces...including just a different air filter sometimes

and yes..sometimes it is a significant change.....it totally depends on the mods..usually exhauts that changes where the O2's sit is the biggest culprit of this problem...and its a very often seen problem on our vehicles

[EC_Tune]

Here's direct info from NGK about zirconia (1- 4) wire and planar sensors (4-wire only)

Actually the manufacturing process for zirconium style o2 sensors is fairly similar across the board. Of course there are Planar styles (most modern) and the older 3 wire and less types. Most of the differences are connection types and lengths of the leads. They virtually all use an 18x1.25 thread pattern.

With a 4-wire heated o2 sensor, the placement is much less critical than with less than 4-wire sensors (3-wire and less are grounded through the exhaust system instead of a separate signal ground)

[steath]

So by doing this you are trying to in essence balance the O2 so that stoich is the middle voltage in the o2 oscillation?

Could this cause a surging while on the gas to 20% TPS? It surges like the proportional fueling is off but when I change the values it has no effect. I am running 60# injectors and a cam with virtually no over lap (turbo).
Sorry to hi-jack this thread but I am looking for the culprit to my surging in the worst way.

[Beatdown Z]

Interesting info in this old thread...

[monte4ever]

Bump for more info from Soundengineer.

[fast400]

Reviving this old thread...I can't the Worksheet.xls to open correctly. Is there something special to consider?

[strokedcoupe]

it downloaded for me and opened fine