Need VE Tuning Opinion

[Dennis93TA]

well i went for a ride and datalogged now i'm ready to start tuning. I went and created a table and crossreferenced RPM vs MAP with LTFT in the middle. So if i did it right it shows me the average LTFT so i take that number and mutiply the original VE number by the correction percent and that would give me my new VE number right? Anyway here is my table. Tell me if i'm doin this right please.

http://img2.putfile.com/thumb/7/18118583476.jpg (http://www.putfile.com/pic.php?img=5848714)

[Doc]

Hi Dennis,
I know you don't want to hear this but, attempting tuning by LTFTs is akin to trying to find your way in a dark room with just a pigmy that keeps running around holding a match that keeps getting blown out. There are plenty of affordable tools out there.

[Dennis93TA]

What do you mean, i thought this was the way to do it? I mean i have a wideband just not hooked up yet.

http://www.ls1tech.com/forums/showthread.php?t=304025

Should i be using STFT?

[joecar]

You will get accurate results using a wideband.

Meanwhile, if you want to use LTFT's, you need to use any ONE of these as your multiplier equation:
1 + LTFT1/100
1 + LTFT2/100
1 + (LTFT1 + LTFT2)/200

i.e. the multiplier is required to be a fraction and not a percentage; e.g. 0.95 == -5%, 1.05 == +5%.

[Dennis93TA]

when i hook my wideband up would i substitute the LTFT's with the wideband reading in the same tabe i already created? I have a 98Z so i can't do the AutoVE right.

I think i'm getting everything confused here. Can someone point me in the right direction for 97-98 tuning. Everything i read says 99-up. Damn bastard years.

[dfe1]

I've never been particularly happy with the results I get using Auto VE, and on occasion I've had to tune without a wide-band, so I use a few alternate methods. Narrow-band sensor readings are fine for tuning VE when you're working with areas of the map that relate to fuel flow for commanded EQ ratio of 1 (14.7:1 air/fuel ratio). Just adjust VE based on LTFT percentages displayed on dash page B, but don't use a one-to-one ratio-- that is, if LTFT is -8%, changing the relevant VE values by 4% won't necessarily result in LTFTs of -4%. Experiment by making smaller percentage changes and you'll get a feel for the proper relationships (they vary from engine to engine). Once you get your wide band hooked up, you can plot commanded versus wide-band AFR on dashpage B to see the VE changes required. Regardless of the method you select, be sure to avoid using data from areas of the graph that have rapid throttle transitions.

[shallow bay]

when i hook my wideband up would i substitute the LTFT's with the wideband reading in the same tabe i already created?
During the AutoVE process, you need use the Base Efficiency Numerator (BEN) PID for your WB. This PID takes actual AFR and divides it by the commanded.


I have a 98Z so i can't do the AutoVE right.

Incorrect. Just make sure when creating the AutoVE Map, your using the {B0103} Backup VE Table. The earlier PCM's default to that table while in SD mode.

[Doc]

Hook up that wideband.

[Dennis93TA]

Thanks guys, hopefully it'll make things easier.

[joecar]

dfe1 is saying to use something like one of these for your table's equation:
1 + LTFT1/200
1 + LTFT2/200
1 + (LTFT1 + LTFT2)/400

[wait4me]

I would sugest first to fix your injector flow rate table, IF you have alot of values that are more than something, like in your instance, you have all cells being off at least -7, I would ADD to the injector flow rate to bring your cells back in line first, THEN just fine tune what is left. If you have to change them all globally like that then it means something else is wrong by a percentage. If you havent CHANGED your FUEL INJECTORS, then dissregard this step as it is not needed to be messed with and your MASS AIR FLOW sensor is the table that needs to be modifed, as you probably changed the accuracy of that with an aftermarket airfilter setup or it is dirty.