2xLS1

iTrader: (25)

What would cause O2s to start out really low, then continue to oscillate at WOT? Vehicle is a 02 6L Truck. First log after small cam (221/.559 112) install still on stock tune. No other mods other than no cats.

CAT3

iTrader: (9)

Fuel trim in the cells prior to WOT being positive (showing a lean) condition will cause this. VE tuning will take care of it, quick dirty way is to go and adjust the VE at those points, but not the correct way to handle it.

jimmyblue

iTrader: (11)

It looks to me like you are not in PE / open loop
despite a 100% indicated TPS.

Check the PE enable settings (MAP, TPS), the
PE mode delay value and RPM threshold. I think
something is locking you out of PE.

Bombguy99z28

Agreed. Even if you carry a positve fuel trim modifier into WOT, you'll still go into open loop.

foff667

iTrader: (2)

easy way to check would setup a status bit or at least see your IPW's

wait4me

iTrader: (10)

The truck has permission to try and tune for the commanded air fuel ratio that is commanded.

That being said, They have shut off Pe mode, If you look at your pe mode delay times and rpm, you will see.

2xLS1

iTrader: (25)

These are the settings in the PCM when I did the log. I had made some edits but nothing I considered tuning yet.
PE Mode Enable Hot and Cold Tables - All cells 90% (stock setting)
Hot/Cold table Thresh - 284 (irrelevent since both tables are the same.)
PE Enable Map - 55Kpa (stock setting)
PE Mode Delay RPM - 2000 (stock setting was 5500) (HPTuners says this is ignored on car calibrations. Does anyone know FOR SURE if it is used on trucks?)
PE Mode Map Hyst - 6
COT - Off
EQ Ratio - All cells stock values.

wait4me

iTrader: (10)

I deal with trucks all day long, Yes it does effect them, You are missing 2 very important checks that arent available to you in hp. Only efilive guys have access to them now.

2xLS1

iTrader: (25)

On a different truck (03 5.3L) I've logged on a dyno, with it's PE Delay RPM set at 5000, it clearly went into OL PE mode at 2800~3000 on 5 different pulls. That is why I question it's use on trucks. Do you agree it's not used on cars? That truck's calibration also had a PE Delay Time paramater set at 2 sec, and it looked like that was delaying it about 2 sec on the log. The 02 6.0L cal I'm working with here does not show that time delay parameter available to me with what I'm using to edit. I'm only using HPT to log trucks, not to edit them. I have a few other PE paramaters available to me.
PE Corr Step Size - 0.020
PE Corr Apply Rate - .05 sec/step
PR Corr Remove Rate - .05 sec/step
Max Alowable Enrichment - 1.400 mult

On the log in question, the truck was at 100% TPS for 10 seconds so I think any time delay should have meen met.

wait4me

iTrader: (10)

the delay on that truck you are having issues with is 60 seconds before entering pe.

Black02SS

iTrader: (36)

Yup. Ran into this when I was tuning my moms 2500 6.0L.

Black02SS

iTrader: (36)

2xLS1

iTrader: (25)

What were the GM engineers thinking when they did that? That makes no sense at all. Thanks for all the help.

jimmyblue

iTrader: (11)

"Hey, Bob, let's make this one ping like a MF for
about a minute every time, just for giggles"?

Once that gets right, then you can see how crazy
low the timing tables are. And how pointless /
oversensitive the burst knock setup is.

2xLS1

iTrader: (25)

I can understand low timing tables and sensitive KR since they are tuned for 87 octane gas, but any delay entering PE with such a heavy vehicle is beyond my reasoning. I looked at some 03 and up 6.0L cals with my tuner and saw the 60 sec delay. I just need to get them to add it to the earlier years. They are great about doing that when I find these things.