LTFT on or off while tuning the MAF table

[legerwn]

In " EC Tunes MAF tuning made easy" he has you turn off the LTFT then tuning the MAF table. With the current VCM Suite there is a LTFT & STFT average selection for setting up the histogram. Do you still need to turn off the LTFT's while tuning the MAF if using this setup?

Thanks Neal

[charcoal03silvy]

I personally use STFT only because LTFTs take longer to learn in, it works just fine. Others prefer to use LTFT only, or STFT+LTFT. All methods are a different means to a similar end. I suggest trying the different ways and see what works best for you. Ultimately you should end up at the same place in the end. If you are using LTFT, make sure to reset the trims after a flash.

[blindsquirrel]

If you are using data from a wideband the trims must be turned off, or else you're recording WB histogram data that's taken after fuel has been added/removed by the trims. If you're not using a WB to gather the data, then you have to use some version of the fuel trim histogram, otherwise you have no error data to apply to the tables.

[legerwn]

thanks for the input, really appreciate the help

Neal

[REDSSV]

LTFT and STFT OFF - How?

[cobaltssoverbooster]

force open loop by setting the requirements for closed loop to thresholds that can not be attained. also make sure the trim option for open loop is set to off.

[legerwn]

CSSOB I've watched your tech videos multiple times, thanks for putting those together they are a great help for us new guys.

So are you saying to still shut off the trims while tuning the MAF table even is using the LTFT & STFT average histogram?

Thanks Neal

[cobaltssoverbooster]

the other users are trying to get the point across that there are 2 modes of tuning and 2 methods of collecting data.
MODES:
mode 1 is Speed Density (SD)- in this case the maf sensor priority is raised to an un-obtainable threshold value and the sensor is then electronically failed through coding to force the ecu to think its broken, thus allowing it to be somewhat ignored by the ecu temporarily for tuning purposes. When operating in this mode we calibrate the Volumetric Efficiency table (VE).
mode 2 is MAF Enhanced (MAF)- in this case the maf sensor is electronically enabled at a very low threshold and the sensor settings are set to allow it to function without failing. typically these sensor settings are just OEM values. In this mode the MAF sensor is given a significantly higher priority when the ecm calculates air density and thus the ve table can be somewhat ignored as its priority is set much lower than the maf table. When in this mode we calibrate the MAF Sensor Calibration tables (MAF Tables).

DATA COLLECTION METHODS
Collection Method 1- Fuel Trims-- When collecting data under the Fuel Trim Method, the vehicle uses the factory O2 sensor circuits to monitor air ratio in the exhaust. The way the OEM computer is programmed, these O2 sensors can normally only be used once the computer goes into closed loop control state. There is a setting that allows the short term trims to be used in open loop control state, but for explanation purposes lets say you need to be in closed loop in order to have both long and short term fuel controls active. This method is fine to use but it has limitations which kind of make the method almost useless in the performance tuning aspect. The main limitation here is the fact that when the system goes into acceleration enrichment or power enrichment, the sensor are temporarily ignored by the ecu in a way and thus data collected when these modes are active becomes junk to us tuners. So, with this collection method you can tune roughly half of your fuel tables and wot/pe tuning is a no go.
Collection method 2-Wideband-- When using a wideband the accuracy of the sensor is increased by a large margin over stock O2 sensors due to its 0-5 volt linear range over the smaller 0-1 volt non-linear oem range. These sensors will read true error (when set up correctly) and have no effect on ecu operation (no trimming). To read true error we need the ecu to run in a forced open loop state so the engine runs the programmed fuel maps without being corrected. if the system were in closed loop then the factory trim system goes live and adjusts the fuel error until the system has minimal error. this means the wideband will just sit in a state of minimal error which doesnt represent the error of the actual calibration table. Tuning with wideband allows us to tune the entire fuel table ranges without limitation as the sensor always reads true operating error when setup correctly, and is accurate in power enrichment modes as well. To disable closed loop, it is common practice to set the closed loop enable coolant temp to a very high temperature well above normal operation. In the open loop section there may be a toggle table for short term activation during open loop. this also needs to be set to disable so at no time will long or short term trims be able to activate and ruin the wideband sensor readings.

you need to pick a data collection method first and foremost and set the ecu up accordingly so the trim activation matched the methods you choose to collect data. it should go without saying that everyone here is going to tell you that the wideband is a critical tuning tool and should be purchased to make a proper calibration adjustments under wot conditions.
from here both methods of collection work for both modes of ecu operation. if you want sd then set the maf to fail and raise its priority; vice-a-versa for maf mode.

you basically have 4 tuning options at this point and need to decide which one you want to work in
1)SD - Trims Active (Wideband useless)
2)MAF - Trims Active (Wideband useless)
3)SD - Wideband (Trims Disabled)
4)MAF - Wideband (Trims Disabled)

we are not telling you to do anything in particular... we are trying to guide you to the correct mode and collection method.
maybe the explanation on the system stuff will help you understand how you are being guided in this particular forum thread.

[legerwn]

Yes Sir I do understand the guidance,

I should have listed that I am not using a wideband at this time. I do currently have and use an Innovate LM1 to tune my vette, BBC 496 solid roller, around 700 HP (carb). I built a 5 volt generator so I could install and log a MAP, TPS, RPM, NB02 and the WB02 using Logworks which allows me to fine tune the carb.

Since I'm new to the ECM tunning I thought I would start with my personal truck, 96 Z71 5.0l stock other than a 0411 ECM upgrade using the NB02's then move up from there.

Thanks for everyones input it is much appreciated,

Neal

[REDSSV]

Thanks from me too!

[cobaltssoverbooster]

cool, let us know if you guys get stuck again.

[123pugsy]

Cobalt, great write up.

Thanks.

[LittleBlue]

Cobalt, this cleared a couple things up for me. Thank you!