LM-1 AFR Readings

[corpsvette]

I am having some problems finding a good place to weld a bung for my LM-1 wideband on an 08 Corvette with stock manifolds. There is no room for a WB sensor. Some have suggest putting it on the top side of the CAT since the honey combs are further down in the cat. I have investigated pulling the B1S1 sensor and replacing with the wideband while using the LM-1 output to deliver the ECU the info it needs to function but I can't decipher the wires. Options are:

HO2S Low Signal Bank 1 Sensor 1
HO2S High Signal Bank 1 Sensor 1
Ignition 1 Voltage
HO2S Heater Low Contorl Bank 1 Sensor 1

I have contemplated going post cat but I understand readings are likely to be leaner. Possilby .3 to .6 difference. Just curious what all the tuners out there think. Where do you do to get your AFR...Tailpipe? Intall a bung just for tuning? Thanks. I am driving myself mad trying to figure out what I want to do. It is so good to be amatuer tuning again. So much to learn.

WHat I have learned so far:
1) No one completely understands TM except folks that keep it a secret.
2) Knock sensors on LS3's are oversensitive
3) Don't bother trying to adjust VE tables (I couldn't even find a VE table) and just use MAF tuning (I gotta find a thread on how to do that).

Much different than my C5 LS1.

[ktoonsez]

You definetely want to install the WB before cats as close to the manifolds as possible or your AFR will be off. I am not sure on your wiring question as I have headers so I had plenty of room for my WB. Your "learned so far" #1 and #2 is accurate. #3 is a matter of opinion and depends on the year of the car I believe (I have an '08 as well), my car is extremely faster with VE and MAF enabled as opposed to running MAF only, you can really feel it off the line and SOTP. Our cars do not have a traditional VE table, we have equations that make a virtual VE table. These equations are under "Engine/Airlfow/Speed Density". Read up on the program "Bluecat" ( a member here) wrote and you will begin to understand how the LS3 handles VE (a.k.a. Speed Density).

[corpsvette]

You definetely want to install the WB before cats as close to the manifolds as possible or your AFR will be off. I am not sure on your wiring question as I have headers so I had plenty of room for my WB. Your "learned so far" #1 and #2 is accurate. #3 is a matter of opinion and depends on the year of the car I believe (I have an '08 as well), my car is extremely faster with VE and MAF enabled as opposed to running MAF only, you can really feel it off the line and SOTP. Our cars do not have a traditional VE table, we have equations that make a virtual VE table. These equations are under "Engine/Airlfow/Speed Density". Read up on the program "Bluecat" ( a member here) wrote and you will begin to understand how the LS3 handles VE (a.k.a. Speed Density).

I did download Bluecat's program and filled in the equation constants table and hit the gen button. I see in the VE table with numbers. At this point I am stuck and I don't understand what I am looking at or what I need to do with these numbers. Would be great if you help me. Thanks.

Jim

[ktoonsez]

First off, did you do any mods to your car that require these tables to be modified?

Here is a nice summary of what to do:
The numbers you are looking at represent a mixture of air and fuel. The higher you make the numbers, the more rich the car gets and vice-versa. So the first thing you need to do is get your WB installed and do some logging of RPM vs. Manifold Absoulte Pressure (just like the table you are looking at after you hit "Gen table" in bluecats program) based on your AFR % Error (this is the % difference between your actual AFR and Commanded). After you are done logging you now have the % to change the VE table by, either +/- depending on you log results. Apply the changes to the table using excel or the "VE Lo Altd" table under General Airflow in your tune (just be sure to zero it back out before writing back to the car), smooth the areas you couldn't hit to maintain the same shape of the table, then generate the equations based on the new table and put them into your tune. If you read the entire post from the place you downloaded it you will learn even more than what I am summarizing here. Hope that helped.

[corpsvette]

THanks a million. I think I got it now. No, I don't have any mods at this time. I am just working for the future. I am off to read some more and try to figure some more things out. I sounded kind of demanding in my previous post which was not my intent, I was just up late. You da man and I appreciate you taking the time to explain it in Barney terms.
Jim

[ktoonsez]

No prob