how accurate are factory ve tables

[zayne0]

as stated how accurate are factory ve tables for a stock engine? I have an 05 corvette (ls2). I have efi live and I am ready to start doing some small modification, cai, headers.... the norm. And I am wondering how accurate the factory tables are for maf an ve. thanks

[n8dogg]

Factory VE tables are very accurate in factory stock engines running MAF/closed loop. You wont need to adjust the VE table with just a CAI, but once you get long tubes you will. I think the LS2 still uses a VE table, I know the LS3 went to a virtual VE table (non existent).

[zayne0]

Factory VE tables are very accurate in factory stock engines running MAF/closed loop. You wont need to adjust the VE table with just a CAI, but once you get long tubes you will. I think the LS2 still uses a VE table, I know the LS3 went to a virtual VE table (non existent).

Could you tell a difference after the mods listed on your zo6?

[Wheelz]

My VE table was within 5% easily and 3% for the majority of the table compared to stock before any modifications after I did a couple iterations of tuning. And my truck has 97k on the clock.

I just installed tri-y headers and haven't had a day to tune yet. it's close enough to drive, but watching my o2 sensor it could use some adjusting

[zayne0]

I've read a lot of the beginner tutorials, but what I get from it is get a wideband do some logging compare commanded values to actual then start changing things.... ?

[Wheelz]

I've read a lot of the beginner tutorials, but what I get from it is get a wideband do some logging compare commanded values to actual then start changing things.... ?

Well.. Your sorta right. You log your wideband lambda reading along with commanded equivalent ratio (and selected other required pids) and then build a map that calculates what each change should be.

Read up on the calc.vet tutorial

[n8dogg]

Could you tell a difference after the mods listed on your zo6?
Yes, especially after the long tube headers and a tune.


I've read a lot of the beginner tutorials, but what I get from it is get a wideband do some logging compare commanded values to actual then start changing things.... ?

I wish it were that easy. I'm still a beginner, I think, 3 years into tuning. I don't think I'll ever fully understand it. But I know enough to get a LS1 car running well with heads/cam. I've recently started to get into LS3/E38 tuning, and that's a different world for me.

My recommendation is to start with gaining a good understanding of basic engine principles first. What does a healthy engine need? Air, Fuel, Spark. How much of it, and when, is what makes the difference from not running at all to running at maximum efficiency, and everything in-between.

Next I'd recommend gaining an understanding of how to tune an old small block with a carb. and distributor. Understand what happens when you have too much or too little spark or fuel. When you get surging, sluggishness, a hard start and dieseling.

Then I'd research EFI systems and understand what each sensor does and why it does it. Learn what fuel trims are and how the engine's computer determines spark and fuel delivery.

Even at this point, you wont know how to tune. You could pick up Greg Banish's tuning tutorial DVD's. Personally I find them boring and my mind wanders, I have a hard time learning by listening. I'm hands on. Some guys on here, especially in the Gen 3 V8 section, are extremely helpful. Ask questions and you will most likely get an answer.

I personally like the Calc.VET tuning. The hardest part is setting it up on the scan tool. After that it's easy and creates a whole new VE table. Which you need to do for headers or anything that changes the airflow characteristics of the engine.

There is much debate on whether or not you need a wideband. You can perform a VE tune, like the Calc.VET tutorial, with out it. You're blind in the WOT region because the narrowbands are not accurate in WOT. But as long as your part throttle tune is accurate, your WOT region normally follows. I do recommend a wideband, because it is safer and more accurate. Most of us tuners are perfectionists and want to know exactly what our engines are doing.

Oh and learn what lambda is and EQR. Start to tune with them from early on to avoid confusion, it's simpler really.

[zayne0]

Ive been to efi university's efi 101. I get "ish" tuning, sensors, basic engine characteristics, etc. its all the different tables that get me confused and getting the software all setup.

[Wheelz]

Honestly you'll learn the most just sitting down one Saturday and doing a calc.vet or .maft. You really learn the software by diving in and trying it. The tutorials will get you pretty far down the right road. It takes a little common sense if you don't have an identical configuration, but it's not bad