MAF tune power enrichment

[SteelGreenStallion]

Does the VE table have any affect on the A/F ratio when in power enrichment?

[kingtal0n]

YES

I think the VE table 'set' a/f ratio is given by the "open EQ" or "open loop EQ" table,

The commanded A/F in PE mode is derived from VE and PE mode values taken together along with other multipliers/influencers

In other words PE values are commanded a/f ratios, but the actual a/f ratio is based on the VE table value not the commanded a/f ratio

for Example Just prior to PE it thinks 'commanded' 14.6:1 VE table values but my true VE table weighted heavily actual A/F is 14.2 or 13.8 values, outside of PE
So when PE mode kicks in and commands say 12.0:1, because it assumes the VE table is tuned to 14.6 and not 14.2 or 13.8 I get more like 11.5 or 11.7:1 actual (example, not my actual desired a/f just an example)

Let me put it another way
Say your VE table value results with actual A/F value of 13:1 but the computer thinks the VE table is tuned to 14.6:1
If you command a 12:1 in PE Mode it will be much richer because the VE table value is already 13:1 , not 14.6

Computer has no way of knowing what the real VE table is tuned to or what the actual a/f is. It only reports what the commanded a/f is, its YOUR job to compare actual with commanded and determine how to handle that situation as a tuner. Beginner tuners often think they need the VE table to be tuned exactly to 14.6 or 14.7 or whatever but the advanced tuning strategy is a blending of VE with PE mode that eliminates any jerky or sudden transition between the two, in Gen3 by accounting for predicted torque and transmission shift behavior and pressure tables compensated appropriately.

[SteelGreenStallion]

So does it just ignore the O2 sensor feed back when in PE? Or is this used to adjust the A/f ratio? All fuel trims go to zero, so is assumed the O2 sensors are what is uses to adjust PE. If I understand your explanation, the VE table is used as base line starting point for the PE table.

[kingtal0n]

Narrowband sensors are useless anywhere except 14.7:1 so there is no way to READ any air/fuel other than 14.7:1 while using Narrowbands.

So when PE comes on there is no way to use a narrowband O2, it must be ignored.
Instead we use a wideband sensor, which can be used at any a/f ratio not just 14.7:1.


Yes VE table is a kind of starting point for PE mode. Just remember there are some other influencial tables, like IAT multiplier for PE.

[smokeshow]

Beginner tuners often think they need the VE table to be tuned exactly to 14.6 or 14.7 or whatever but the advanced tuning strategy is a blending of VE with PE mode that eliminates any jerky or sudden transition between the two

The PE ramp cals do the blending. Not the VE.

[kingtal0n]

The PE ramp cals do the blending. Not the VE.

I see your life revolves around me now like so many others.

Your opinion about the way to tune, is YOUR opinion. You are a beginner tuner and have no perspective or imagination which also leads you to become a follower, copy what others and the original ECU have set out for you. Like a set of tools intended to be used a certain way: a Hammer, a Fork, a Bell. You would use the hammer on nails, I Use it as a doorstop. You would use a fork to eat, I use it as picture on the wall. You would use a Bell to ring, I use it as a cup. You tell me I do these things WRONG yet I can see from my perspective these items have this use and so many others.

I Make my own rules, I create my own software, I use my own methods.

Also thanks for PMing me insults and calling me names all the time. Its been a great way to identify how small you think so I don't waste my time on you.

[eXo3901]

Does the VE table have any affect on the A/F ratio when in power enrichment?

Commanded PE A/F, No. Actual PE A/F, yes but MAF, IAT, spark, and many other things all contribute to the final A/F you may see on a wideband gauge. Depending on your setup MAF/VE are the main places to adjust to achieve your desired A/F ratio when in PE. When adjusting these tables if the values are abnormally high or low then you have issues elsewhere, probably injector data.

So does it just ignore the O2 sensor feed back when in PE? Or is this used to adjust the A/f ratio? All fuel trims go to zero, so is assumed the O2 sensors are what is uses to adjust PE. If I understand your explanation, the VE table is used as base line starting point for the PE table.

O2 sensor feedback is ignored while PE is active. The computer goes from a closed loop feedback control(which uses O2 feedback to adjust fueling to achieve the commanded A/F ratio) to an open loop control when it enters PE(no feedback control from O2). The VE table is a representation of airflow through the motor. A baseline for PE? I would say no because that leads people to manipulate the PE table to achieve their desired PE A/F ratio. When they should really just enter their desired A/F ratio data in the PE table and tune the VE table to achieve the desired A/F ratio when in PE, for which you need a wideband. Narrowbands are not precise enough at the popular PE A/F ratios we want to run at. PE is essentially just a multiplier/divisor to the commanded A/F ratio set in the tune.

[smokeshow]

Since I prefer to contribute and not just talk about myself, here are some free tools to use to compare gen 3 VE to MAF.

This math parameter and histogram will allow you to plot a VE table based on MAF readings, much like the gen 4 GMVE/MAF writeup I did a couple years ago. You just have to change the displacement (divided by two - the value circled in red is half that of a 5.7L) as the volume component of the cylinder airmass calculation must be accounted for explicitly, compared to the implicit volume in the GMVE values. Use MAT if available, in place of IAT.

Filtering and steady state stuff is up to you See my other succinct, less-than-a-wall-of-text writeup I did on this concept for gen 4 applications for more in-depth discussion.

https://forum.hptuners.com/showthrea...ation-for-gen4


Calculated VE.jpg Displacement.jpg


VE calc from STFT MAF.MathParameter.xml

VE calc MAF.Table.xml

[eXo3901]

Thank you.

[SteelGreenStallion]

I'm flattered by all the response this has got. The main issue I'm dealing with is the actual A/F ratio is always about .5 leader than the commanded when in PE at WOT ( I have an AEM wideband in the car) I've never touched the VE or the timing since I changed the cam on the 5.3 LS two years ago. I only made changes to idle settings and the car runs good. The average cruising A/F is close to 14.7 but its not steady . I don't know if this in normal but I assume that its because the VE has not been tuned. Probably why the actual and commanded don't match when in PE. I'm in information overload right now. I have to digest everyone's input. I'm going to make a pull on the car then post the log and tune later. Thanks for everyone's comments.