Here is my tune and a little scan of taking the car down the road.
The original tune was for a 2006 4.8 with 4L60e. I've since swapped in a budget built 5.3 with a large comp cam from the early 2000's. I had the cam so I used it. I did a little home porting on the 706 heads. All stock internals with fresh bearings and rings. Using the factory intake from the 2006 4.8. Running a truck exhaust manifold on the passenger side, and a cheap chinese long tube header on the driver's side. (Long story) There is an exhaust leak after the sensor on the passenger side.
Has a fresh built 4L60e with a trailblazer torque converter. 3.42 gears. 3400 lb car.
This is a VERY low budget build. Keeping with the 'penny pincher' theme, I am attempting to tune this thing myself. I am quite proud of the fact that it starts up and idles. My thanks go out to the wealth of information provided on these forums.
Take a look if you'd like. I am open to all criticism and advice.
Does this thing have a lot to be desired? I have a wideband, but have yet to install it. For start up purposes, does it appear on the right track? Thanks for looking.
Even if a leak is after the O2 sensor, it can still draw outside air back up the pipe to where the sensor is. Needs to be fixed. Probably won't be much fun trying to tune around such different exhaust on each bank either.
This section in your log, where during cruise it goes from commanding stoich to commanding 16.00(see note below) then to commanding 13.6 and then back to stoich...
...that's the PCM trying to run the post-cat O2 test, and it can't because they've been removed, and that test can't be truly disabled on Gen 3s. Hopefully you didn't chop those wires out of the harness, because it won't ever stop doing that until you plug some rear O2s back in. They don't need to be in the pipe but they do need to be electrically present.
(note: please teach yourself now to use EQ Ratio instead of AFR. Same for logging vacuum in-hg. Leave it behind. Learn to use the same units the PCM uses in its tables.)
Blindsquirrel, you're a rock star, dude. I get a lot info from your post. Short, sweet, and to the point. Thanks!
Unfortunately, the rear O2 wiring is gone. Thanks for taking a look and offering up some advice. I'll certainly take those into consideration.
When you say 'learn to use EQ Ratio' are you referring to the system that uses Lambda measuring units?
The PCM thinks in EQ, but it can display what AFR that converts to for human brains that are still stuck in the past. EQ is in Phi which is like Lambda, just reversed - above 1.0 is rich where in Lambda, above 1.0 is lean. Stoich is at 1.00 for both.
Your PE settings look pretty miserable. You lowered the Throttle Hot table but it doesn't use that one unless it's above 285*F (which is hopefully 'never'), Throttle Cold is still at 90%. Min MAP is too low (looks like your 'large cam' idles at 65-70kPa?). Raise Min MAP to like 85kPa. Lower Min Torque to 50% or so. Lower Throttle Cold table to something reasonable like 60% from 0-2000, 20% from 4000-7200, then blend the area in the middle. Set the entire PE EQ Ratio table to 1.18 (12.4 AFR, .85 Lambda). Zero out both the Delay RPM & time. Enrichment Rate to 2.00.
Depending on just how large this 'large cam' is you're going to use up those puny 24lb injectors right quick like (assuming you reused the top end from the 2006 4.8 - you didn't answer which injectors you used). The logfile doesn't go over 2800 RPM/.45g/s so the data isn't there to see at what point the duty cycle will hit 100%, but unless it just doesn't make any power it'll never make it to your 6K rev limit without running out of injector.
Is there ever a time that a tuner says, 'finished, got it perfect, no more tinkering'? I want to get this car to where it has compromises, but it remains enjoyable to drive.
Appreciate the pointers. I'll spend some time digging into it. I'll post up those cam specs next post, along with the exact number on the injectors. I've read that injector MUST be correct. I notice you emphasize that over and over. Enjoy the holidays!
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