simple ve LTFTs question

[mayne]

Negative LTFTs means that its running rich and trying to pull fuel from the VE to lean it out?
Positive LTFTs means its running lean so its trying to ADD fuel to the VE to richen it out?

sorry, its just been FOREVER since I've been tuning... just trying to remember

I'm sure I'm right

1) When trying to tune VE we reset the computers old programmings(LTFTs/STFTs)?
2) Drive around for a couple hours or days to let it relearn LTFTs/STFTs.
3) Then we log in SD mode(no maf) correct? So that it runs only off the VE table? for 30 minutes to 1 hr.
4) We use the SD log to correct the VE by using the LTFTs we got during the SD mode?
Correct?

[passingpower]

Correct. Except, if you do step 2 with the MAF enabled, any errors in the MAFcal will be transferred (learned) to the fuel trims. If you then "correct" the VE table with those trims, you'll be transferring MAF errors to your VE. Learn and log in SD mode.

Some will tell you the whole excercise is a waste of time for a V6. If you review the V6 VEs over the years, you'll see that GMpowertrain "wasted" a lot of time and more money calibrating them. That's proof enough to me that they deserve some attention. Do we need to tune as carefully as the V8s in full time SD mode? Obviously not. Just get close. Transient fueling will smooth out greately making future logs more trustworthy and limp home will be more drivable.

[mayne]

CORRECTED:

1) When trying to tune VE we reset the computers old programmings(LTFTs/STFTs)? UNPLUG MAF!
2) Drive around for a couple hours or days to let it relearn LTFTs/STFTs.(SD MODE!)
3) Then we log in SD mode(no maf) correct? So that it runs only off the VE table? for 30 minutes to 1 hr.
4) We use the SD log to correct the VE by using the LTFTs we got during the SD mode?
Correct?

maybe thats the problem I was having along time ago? I let the ve relearn before I tuned which is a no no

Transient fueling will smooth out greately making future logs more trustworthy and limp home will be more drivable.

lol Limp home is more what I do haha

THANKS ALOT!!!

[mayne]

this entire thread was meant to be wideband-LESS
no widebands! (only for WOT)

[mayne]

So I should be tuning the main VE first and then MAF next?

[passingpower]

In all honesty, I had terrible tuning results until I followed HPT's proceedure for calibrating the IFR table AND researching the true Stoichiometric ratio for the gas I'm burning. In my experience, I'd calibrate the Stoich (if nessessary) and the IFR tables before anything else.
It really doesn't matter if you tune MAF or VE first as long as you use a very steady throttle during MAF tuning. That will minimize AE's effect as well as other transients.
Use a MAF freq vs. LTFT table and filter out decelleration cells. If your data has been gathered during steady state, your NB readings will be more reliable. Remember, when the NB reads 450mv, that is definitly stoich for that particular fuel, NOT nessessarily 14.68:1!

[mayne]

this stuff you are speaking of is new to me.
wow, I wouldve thought that 450mv is way lean

[passingpower]

Under WOT, 450 would be lean - no power enrichment.
In closed loop, it's stoich.

[mayne]

Use a MAF freq vs. LTFT table and filter out decelleration cells. If your data has been gathered during steady state, your NB readings will be more reliable.

1) Whats steady state?
I will make sure to use slow and steady transitions when decelerating and accelerating.

MORE THAN ANYTHING, I want to tune my MAF just so the car drives okay.
2) should I do a case learn before the IFR adjustment?
3) I dont know how to setup my IFR table. Is there a link to where to learn how to do it?
I will do an SD log today

[passingpower]

I use the term steady state to mean very little throttle movement. That minimizes AE's influence on your scans. Go here;
http://www.hptuners.com/forum/showth...highlight=Cpig
read all the posts and download the doc in the final post. Even though it's written for V8s, most of it applies to us. You'll need a CASE learn only if you swapped PCMs, and even then, it's not always needed.

[passingpower]

IFR calibration link
http://www.hptuners.com/forum/showthread.php?t=10605

[Perforator]

Unless you've changed injectors I wouldn't touch the injector flow rate table.

[mayne]

yea, i havent and am scared to touch the IFR table
I dont need it SUPER close I just need it running decent.

If a car has had a P&P intake and heads it might be flowing more air? correct?
So would you ADD to the VE table or SUBTRACT from the VE table to get it closer?

I tried driving it tonight, I had to let it heat up to temp. Once I let it heat up, I pulled the MAF plug to make it run in SD mode,
but it immediately died. I KNOW I'm LEAN. What do I do? It wont start back up
Yes, Im begging for help

[passingpower]

Before we get to specific troubleshooting, tell us what you're driving and everything you've done to it. Perf is right, you likely don't need to cal your IFR table. The only reason I cal'd my stockers was to practice for my 42.5s.

[mayne]

only thing done to it is K&N, flowmaster muffler, P&P intakes and heads
that is all I can think of thanks

[passingpower]

I still need to know what engine you're running so I can begin to guess why it cut out when the MAF "failed". For instance, right now I can't tell if you unplugged just the MAF or the IAT sensor as well. Is that K&N an open cone in the engine bay, or part of a CAI? That Flowmaster is only the muffler and not any tubing right? Correct, the porting will add to the VE table. It's ok if you can't run in SD mode right now anyway. Just start with a MAF calibration. Being that you're running a V6, the VE table has less (not zero) influence on drivability than on V8s. BTW, what state are you living in? More to the point - do you know if your fuel contains any ethanol? Not that it makes a huge difference in a tune but, knowing this and compensating for it will make the tuning process more straight forward.

[mayne]

v6 3.8L 3800 series II from 2002
the K&N is just a flat filter but has alot of airflow
the flowmaster is just the muffler no tubing but has alot of flow
if you want to get into specifics there is a semi-hollowed out high flow cat
my fuel may contain up to 10% ethanol
so I should tune the MAF first - do I need a WB for that?
thanks

[passingpower]

Last question, are you supercharged or normal aspiration.
That filter will have enough effect on the MAF to warrant a recalibration. (But then again, so does driving off the dealership’s show lot) Another tip, clean that filter and the MAF sensor. Use carb/T-body spray cleaner and don’t touch the wires with anything but the spray. You’ll have the easiest time if you remove the MAF from the T-body. Almost forgot, do you still have the screen in front of the MAF? If yes, keep it. If not, that can introduce quite a bit of variability to the MAF data depending on the ductwork. You have the stock F-duct, consider putting a screen back in.
There are other things different in your setup than the factory calibration. None of them large but, they can gang-up to make tuning difficult. Before starting to tune let your PCM know what stoich is for the gas you are burning. 0% ethanol is 14.68:1 10% ethanol is 14.13:1 (according to Greg Banish) “May contain up to” is a dead giveaway that you need to split the difference by setting Stoich AFR to 14.4:1. That way you’ll be a lot closer – and occasionally dead on – in your calibration.
You can tune the MAF for idle, cruise and light acceleration using the NB as long as you stay out of open loop Power Enrichment. You will read in write-ups to disable PE by raising the PE enable Hot threshold to 100%. Doing this is inherently risky and ill-advised when you compare the cost of a WB sensor to the cost of a new engine. There, that’s been said. If you do decide to tune high throttle/airflow settings with a narrow band, you are hereby warned that you do so without the protection of Power Enrichment. Without PE it’s easy to blow a head gasket or send a chunk or piston half way out an exhaust port with detonation or even pre-ignition. You can guard against knock by monitoring KR EVERY time you tune and log. If you see KR of one degree or more, let off the throttle! Remember, you’ve been warned.

[mayne]

I still have my T-body SCREEN! made that mistake before.
The 14.4 idea sounds brilliant!
I have never seen Knock even though I KNOW I am Lean!!
I dont want to tune PE or remove PE
I just want the car to be a decent daily driver

1) How would someone tune their maf via NBs? I'm aiming for around 450mv?
2) Also, if I were trying to tune the VE and am LEAN would I add or subtract from the VE?

I'm ready to get this done thanks

[Perforator]

If you are lean you add fuel, rich subtract. As far as tuning goes, HPT has histograms you could use but personally I like to use an Excel spreadsheet. I would skip the VE table. It's not what you need to change to get fuel trims in line. The MAF table is what you need to be modifying. To tune with the narrowband you use the LTFT value as a percentage to modify the MAF table with vs MAF frequency. I would filter out any frames that are not 14.7:1 and any frames that are fuel trim cell 1 which is decel.