VE Tuning

[txfour]

I am wanting to tune my VE tables. I am on stock O2's. Is there a how to guide I am not seeing somewhere?
Thanks!

[txfour]

Here is my current process.

I have MAF set to 0 and unplugged
I have copied high octane table to low octane table.

I started the scanner and logged for about 25 minutes hitting as much as I could.

Came back and took the values from LTFT and applied them to primary VE table. For instance, if it showed -15 in column 2.4/40, i reduced that number by 15.

Clicked "relearn LTFT" and went for another drive and logged again and made those adustments.

I'm just not getting there. The histogram is getting ugly as can be. Have taken 10-30% out of my VE table. I don't think I have something right.

[5FDP]

Don't unplug the MAF, that has your IAT sensor in it. You need the IAT, if IAT temps read -38 all the time it's going to screw everything up.

Set MAF fail high to zero, set your 3 MAF DTC"s to fail on first error to put you in speed density.

I never read up on LTFT + STFT tuning for VE because a wideband is easy to use for me. You can't tune WOT without a wideband either.

[dermotw]

Hi, look in the stickies, there is at least one guide there somewhere! Depending on your ECU, you might have a prmary & seconday VE table. If you do it uses the SECONDARY ONE when the MAF is 'killed'... so you have to go through an (annoying) process to copy between...

[txfour]

Hi, look in the stickies, there is at least one guide there somewhere! Depending on your ECU, you might have a prmary & seconday VE table. If you do it uses the SECONDARY ONE when the MAF is 'killed'... so you have to go through an (annoying) process to copy between...

Could not find the how to anywhere. Got a link?

I only have a primary VE table on my ECU.

[txfour]

Don't unplug the MAF, that has your IAT sensor in it. You need the IAT, if IAT temps read -38 all the time it's going to screw everything up.

Set MAF fail high to zero, set your 3 MAF DTC"s to fail on first error to put you in speed density.

I never read up on LTFT + STFT tuning for VE because a wideband is easy to use for me. You can't tune WOT without a wideband either.

O-M-G!!!!!!!!!!!!!!! That's why i am chasing my tail........and my IAT keeps reading -38!!!!

Geez, this is where the how to would come in handy.

[txfour]

So, let me reconnect my MAF, make the DTC changes and try again.

So after my log and I adjust the tables. I'l make a second run to see the changes. Before that run I click on "LTFT Reset" but do I want to have LTFT Learn in the on or off position?

[dermotw]

Well, you could start with this, it's in the top of this forum page stickies, but if you search around you'll find more...

http://www.hptuners.com/forum/showthread.php?t=3833

EDIT: Just be aware that most of what is in the stickies was written for the 'old' HPT and can be a bit out of date, some of the things they mention aren't maybe necessary now (like creating your own math parameters etc.) because they are available in HPT nowadays anyway. Also see this, I forget where it was but on here somewhere;

Tuning.doc

Again, it is quite old, it is pretty accurate for my old '99 ECU, but some details even then have changed as HPT has improved.

[dermotw]

And this, to be honest I forgot who wrote it, not me! -you don't have WB I think;


Step by Step for SD tuning Narrowband (stock) o2' Method:
1st a couple of things to keep in mind:
a: This method will not be as accurate as the one above, but it should get you real close for part throttle.
b: Please keep in mind that depending on where you have your PE enable settings, you will probably only get "0" LTFT values in your histogram after 4,000 RPM.
c: For WOT you will still need a WBo2.
d: There will always be a 2-4% change in learning from day to day. Weather, fuel, and engine dynamics vary quite a bit. It’s the VCM's job to learn these corrections. It is recommended that all tuning sessions be done in like weather conditions.
e: There are two methods of using the LTFT's to correct the VE table, below is a description of the two taken from the HPTuners help file. I will try to elaborate a little more on them.
1: Unplug MAF (Replace with strait bellows if you do not have intentions of ever using a MAF again ie. always speed density.)
2: Disable the SES lights for MAF codes P0101, P0102, P0103 (No check engine light.) Do not completely disable the codes or the PCM will not fall into SD mode. Only turn off the SES light, DO NOT DISABLE THE CODES THEMSELVES!
3: Copy High Octane table to the Low Octane Table (computer reverts to low octane table when MAF is unplugged, this assure optimal timing)
4:Write your file to the VCM and go for a drive approx 20-30 minutes, and try and hit has many cells as possible. Use the "default" config file and scan your LTFT's and STFT's into the histogram.
5: After you have logged sufficient data, it is now time to look at what changes you need to make. This will require looking at both the LTFT and STFT data on a cell by cell basis.
a: If the majority of your LTFT cells, are greater than a 10% swing (+- 10), then refer to method 1.
b: If the majority of your LTFT cells, fall between +-10% then refer to method 2.

Method 1 using the LTFT and STFT corrections from the scanner histogram data:
The VE table corrections can be derived by the following formula:
(+-LTFT%) + (+-STFT%) = Final % Learned
If your LTFT histogram value @1600 RPM, 30 kPa Map is +7 and the associated STFT value is -2 your total % fuel correction is +5. Use about ? the correction (2.5%) on the VE table cell @1600 RPM 30 kPa Map to avoid overshoot.

Repeat this process for any LTFT histogram value until you see a +- 4% range. After you reflash your VCM with the new VE table, use the VCM Controls function to reset the fuel trims before you start recording new data. This will give you a “clean slate” to work with.

It will take you the better part of an afternoon to log the LTFT, make the corrections to the VE table, then verify the results on the histogram again.

Method 2 using the STFT corrections only from the scanner histogram data:
This will require you to disable the LTFT process.
Use of this method requires your VE table to be no more than 10% off. If your VE table is beyond this, start with method 1 first.

Depending on your model you can either turn the LTFT enable option to “Off” (Edit>Engine>Fuel Control>Open &Closed Loop>Long Term Fuel Trim Enable = OFF) or set the LTFT minimum Engine Coolant Temp (ECT) to its maximum value. Using the scanner reset your Fuel Trims. Go for a drive and record the STFT's.

The above step of disabling the LTFT learning process will let the VCM run the STFT correction, but no make any LTFT corrections.
The advantage to this is you only have to use the STFT table on the histogram to get your fuel % correction values. You no longer have to do the (+-LTFT %) + (+-STFT %) math or keep track of the LTFT cell number in use.
The number derived in the histogram can now be used as a 1:1 ratio in the VE table. So, if you are showing -7 in your histogram, you could subtract 7 from the corresponding VE cell, the net result should be a value closer to 0 during your next logging session.

This will take you about ? the time to log the STFT, make the corrections to the VE table, then verify the results on the histogram again.
Once you have achieved a histogram of near 0 values, you can go back into the editor and re-enable your trims.

[SultanHassanMasTuning]

if your looking to stay in speed density then you can upgrade your OS and have RTT