VE tuning with HPT Wideband and Narrowband how to
Guys feel free to read and discuss. I will make changes as we see necessary through our discussions.
Tuning the VE table in HPtuners. Wideband and Narrowband methods.
The LTFT values are your indicator of how much error is in your Volumetric Efficiency table. If Block Learn is at 0% everything is just right. If your STFT is more than 3 % away from 0 , the LTFT value is still "learning". A motor is considered well tuned to have LTFT values between +- 4%. Not every motor can achieve this though.
Step by Step for SD tuning Wideband Method:
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: Mod edit, this step is icorrect. Make sure the OLFA table commands 1.00 in operating coolant temperature ranges.
4: Change all points in the Closed Loop Enable Coolant Temp vs IAT table to 250* (Disables closed loop)
5: Copy High Octane table to the Low Octane Table (computer reverts to low octane table when MAF is unplugged, this assure optimal timing)
6: Mod edit, this step is incorrect. Leave the PE as desired
7: Logging can be done setting up the scanner and custom histogram with HPT 2.0, you want to hit as many cells as possible with the highest count as possible. Setting the filter for 25 cell counts will help ensure accurate data.
8: Change all points in the Closed Loop Enable Coolant Temp vs IAT table back to stock (re-enables closed loop operation and fuel trim leaning)
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 recomened 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 ½ 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 the above method 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 ½ the time to log the STFT, make the corrections to the VE table, then verify the results on the histogram again.
Once you have a achieved a histogram of near 0 values, you can go back into the editor and re-enable your trims.
WS6Snake-eater
Matt
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Originally Posted by WS6snake-eater
