I have a rich WOT AFR and want to lean it out (11.2 average @100% TPS)
I have also noticed 10.8 @ WOT in the lower RPM range. I have adjusted the Open Loop EQ ratio a little (-.03) but not a big difference noticed. In an article of GMHTP they decreased the Injector flow rate to lean out their WOT AFR. Anyone ever done this?

 

The only time you want to change the IFR Table is when you change injectors. Tuning the AFR with the IFR and/or PE Table to get desired AFR numbers is the old school method of tuning (aka: butchering). The proper way of adjusting the fuel for rich/lean conditions is to modify the VE Table (SD setups) or MAF Table (MAF setups) so that it matches the Commanded AFR. The Commanded AFR is dictated by the OLFA Table, Stoich Value, PE Table (some others as well like COT). Once you set you should not touch them. These tables will set the desired target AFR, then you adjust the VE/MAF tables to corrolate the actual AFR with the desired (Commanded) AFR.

 

The car has had minor tuning by RWTD and he changed both these tables, should I copy and paste stock tables back and try getting the VE and MAF tables right?

BTW what does OLFA mean? Open Loop ? ?

Here's a compare of a stock tune vs these current tables, just shows the difference.


How's my VE table look?

 

do you have NEGATIVE IFR values? why is your OLFA almost all 0's? am i having a nightmare? what kind of car is it?

 

he's using the compare feature to show the DIFFERENCE between a stock file & the RWTD file.

 

oh ok this makes helluva more sense now...just post the tune man, we'll take a look at it, there's a lot of stuff you gotta look at to make any decent conclusions

 

Yeah, this is such a valuable feature! I would have no clue how bad my VCM tune was "Butchered" if it we'rent for this handy little feature!

 

OK here you go.


Bill, please chime in and let me know if I'm posting info I'm not supposed to. Thanks.

 

Its great for using when you upgrade to a different OS since you can just do a compare & use the comparison-copy all feature to swap over everything from the old tune to the new. I believe HPTuners is the only software that will allow you to compare two unalike operating systems

 

I am DEFINATLY not regretting buying HP Tuner's. I just wish I would have gotten it a lot sooner!

 

Over the years peoples' idea of how to tune AFR
properly has evolved. Used to be everybody said
change the MAF table. But the MAF doesn't just
go changing on you (minus contamination or
Dremel buggery) so why mess that around? The
side effects are not desirable either.

Then the thinking was, change the IFR to get the
right answer for fueling. But similarly, if you have
a table that faithfully represents the fuel delivery
then there has to be a better way to the desired
result than adding one more lie to the mess. Now,
you do want to verify as much as possible the fuel
pressure at the rails, the injector type and flow at
said pressure, just so you believe what GM had to
say about it. Some of this might be "yeah, stock"
and some might want a pressure gauge you can
read at WOT. But looks like your fueling is not
having a pressure problem.

What you want first, before adding a bunch of
overlapping garbage data to the mix, is to see
where the fueling (AFR) falls relative to what is
commanded. You can command the wrong or
right fueling and you can use bad or good air
and fuel inputs. But if you're starting from stock,
clean and tight, there probably are not too many
bad inputs and your rich fueling is on the command
side.

Log your commanded fuel air multiplier (aka EQ Ratio).
This will follow the PE or the OLFA (EQ) table plus
adders plus the occasional cat overtemp protection
hose-down. Whatever the commanded EQ is, you can
follow it back to the source and you can dope out
which needs changing. Most likely PE and COT are
the stock setup problems, both over-fat from the
factory.

14.7/EQ is your commanded AFR. I like to work with
EQ because that's the basis for all the tables. AFR
is what everybody talks about but you have to flip
it over to line up with the tune data.

When you go to adjust the data side, try and stick
to the elements you think most likely to (a) have
changed and (b) be used in-the-moment (e.g. MAF
is a minor contributor at idle and SD is ignored at
steady-MAP high-RPM operation).

Be sure you do not have a low-end mis-trimming
or a trimming response to mods, laying down more
fuel up top (LTFT values at WOT). Trims will drive
you away from commanded, back door style.

 

Thanks for the info! So I guess I need to change the IFR back to stock, reset the timing tables to stock (high and low octane), reset the IFR , and start CL Ve tuning right(unplug the maf and turn the ses function to "no error reported")? Then where do I go to lean out my WOT or OL/PE AFR, dont know a whoe lot so you gotta spell it out for me lol@ me!

EDIT: My COT is turned off VIA RWTD, and I have a Racetronix Fuel system. Would this affect what or where I need to tune?

 

Nice write-up Jimmy. Thanks!

 

I do have an LM1, that's why I know something is bad wrong. The IFR has been reduced as well as the OLFA (or EQ ratio) but the car is still pig rich (11.2 @ WOT in 3rd gear) with KR that's what I'm trying to fix but not sure where to start. I welcome any advice! Thanks

 

Feelings?

Plenty o sponsors here can set you up with a wideband for alot less than 500

Without a wideband? When you actually have more mods than just bolt ons, fueling becomes more and more critical. Do you want to depend upon pseudo science and guessing with a forced induction setup or NO2? Take the high road, there are many published accounts of how to put your car into Open loop Speed Density and retune the VE table with a wideband. That is after you undo any lies setup by others with Injector Values or whatnot. Make sure to turn off your fuel trims and reset any previously stored values before you begin SD tuning. After successfully retuning the VE tables which can be done relatively easily with immediate results (even quicker with Hp's realtime or EFI Live's RR), turn the MAF back on if you choose to run it. Don't turn your trims back on yet. Rescale the MAF. Done. The modding bug bites us all who travel these boards, it starts out with bolt ons, the H/C, power adders, build your tuning house with a solid foundation for the future instead of getting cheesy and sleezy.

 

OK this is the method I have been wanting to know about, I know I unplug the MAF and turn off the ses light to get it to stay in CL. Then what? Ive heard that from there I need to copy my high octane timing table to my low octane timing table. What I'm not sure of is how to turn off the fuel trims and how to Rescale the MAF. And when I'm done do I need to paste a copy of the timing table back to the way it was before? Thanks!

 

I completely agree with Doc!

Tuning the VE and MAF is not that hard, especially with a wideband. I can have the two precisely tuned and inline with the commanded AFR in two hours of street driving time. Then when I go to the dyno, I am assured that the AFR I command using the PE Table will be correct as verified yet again by the wideband. VE and MAF Tuning is not controversial, tuning using the IFR and PE Table to get the WOT fuel only is controversial. There are proper methods of going about doing things, do not take the short cut because it gets answer quickly. Think about it in terms of building an engine ... you wouldn't use shortcuts to build it, you would build it the correct way.

 

So once I get my VE table right and my MAF rescaled, what parameters in the PE section do I use to comand the right WOT AFR?

 

The Tuning stickies have all the info you need, but I will breifly explain it here:

1. In your closed loop enable temp table, set it to the highest value
2. Disbale the fuel trims
3. Set your OLFA table to 1, you want to target a non-moving commanded AFR
4. Disable any AFR modifiers (such as COT, DFCO, PE AFR vs. ECT, etc.), you don't want any interferrence from outside tables
5. Copy HO timing table to LO, you don't want spark butting into the tuning
6. Set your entire PE table to command 12.8 (this is my method for N/A, 12.0 for boost), this is just to get the fueling correct, after you can adjust the commanded AFR to get you the most power as verified with a dyno
7. set MAF Fail to zero, you can Disable the SES light if you wish (I do )
8. Use your histograms to verify the fuel and make the changes to the VE table, once the AFR is with in 1%+/- you are done
9. Reset the MAF Fail to the stock setting and use the MAF histogram to correct for fuel differences with in the same range (+/- 1%)
10. Once the fuel is to your liking, re-enable closed loop and allow the PCM to learn the new tune.

You first set the PE Table to command the target AFR you want (1.143 = 12.8 if your Stoich is 14.63), then use the wideband to zero in on that target. Once this table is set to the AFR you desire, you do not change it. Unless you want to command a different AFR (verify it using a dyno for best power results once the tune is done).

 

yup, thats how I do it, in the end my o2 sensors & or maf could fall off the car or all out fail & the car would drive identically. It takes very little more time to put together a good tune this way & to be honest it gives me that fuzzy feeling inside knowing my commanded a/f ratio always matches my actual. And like George said when you hit the dyno to find max power you already know what that commanded afr will run on the street