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Thread: LTFT not working

  1. #1
    Senior Member
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    Default LTFT not working

    My cars been down for a few years and getting it back up and running and working on the tune. In the past I was using calc.maft and had both STFT and LTFT disabled to help dial in the VE based off the wide band. Is this necessary? Looking at how calc.maft process works it should take into account the ltft.

    I tried enabling my ltft and for some reason they show 0 the entire time, but I'm not sure why. I checked and the o2's are all plugged in and ready to go. Attached is my tune, is there something I'm missing that i need to enable to see ltft and stft again?

    I also attached a short log which shows the ltft at 0 the entire time.
    Attached Files Attached Files

  2. #2
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    One other question is I'm running e85 and have set B3601 to 10 as this is the lowest value you can enter even though I need 9.7:1 stoich value. Should I put it to this or leave it at 14.7:1? reason being is the LC1 is reading on a gas scale of stoich being 14.7:1. I'm wondering if this will mess up the calc.maft process?

  3. #3
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    Both CALC.MAFT and CALC.VET will utilize LTFT to correct your MAF/VE tables. If LTFTs are disabled, corrections will be based only on wideband readings. You may want to set B4105 to 450 across the board so your outputs aren't skewed while tuning.

    B3601 shows that EFILive's limits are 10.00-20.00, but your controller's limits are 0.06-4096.00. Go ahead and change it to 9.7, do a log and see if your commanded AFR changes.

    You may want to look at your PE modifiers as well. B3613 is set very high, basically you have to bet at WOT to enter PE, which may not be the case if you haven't quite floored the gas pedal but should still enter PE. That could make a lean condition when you don't want one.

    Take a look at B3809, your RPM boundaries for LTFT aren't very useful. Try setting them to 850, 2000, and 3000. Once LTFTs start working for you, this should give them a more useful range to work.

    Your log is only 1.5 minutes long, LTFTs may take more time to update. Log during a long drive and see what happens, aim for 15,000 or more frames in your log. Add your STFT PIDs as well, don't worry if you go over 24 channels when you add them.

  4. #4
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    Thank you for the help i will try some of these changes to see. The log was short because i was testing out adding some airflow to the startup and idle tables. In previous logs which are longer the LTFT never worked either. However in this log the wb started reading funny so I need to figure out what is going on with it.

    B3601 if i enter 9.7 it changes it to 10.0, as it won't let me set it to anything lower, so I'm stuck at that. My question is what does this value really do? if i am logging AFR in lambda or a gas scale, does B3601 really make a difference? Does it affect how the corrects to the VE table are made? Reason i ask is I remember leaving it at 14.7:1 for a long time until i think Joecar suggested to change it for teh fuel type, but I can't do it. Probably is trivial, but wondering if it cause any issues putting it back to 14.7:1

    I should have mentioned this is a turbo car. I have B3613 set to 14psi so that it won't Enter PE mode until it is making boost. Thus is leaner to help spool quicker, then will richen up once boost is made. Also it will be using table B3647 commanded fuel vs RPM table and until it enters PE which is set to a safer value then stoich.

    B3809 is set to stock values, it is set to 2500, 6502, 6503. Is this saying that LTFT will only work between 2500 and 6502 rpm? Thus they are never working at idle?

  5. #5
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    Your OS doesn't support flex fuel, since you're running E85 you need to define the correct AFR for stoichiometry based on what fuel you'll be running. If you're always running E85, you need to define it as 9.7, otherwise the engine will run too lean. B3601 is where this definition is found. Make sure you have EFILive updated to the latest version, I can change B3601 to 9.97 and save the file without issue.

    CALC.MAFT and CALC.VET use equivalence ratio (the inverse of lambda) to correct fueling from data logs. It doesn't matter if your AFR is 5:1, 14.68:1, or 100:1, equivalence ratio and lambda will both read 1.00 when your engine is actually at that commanded AFR. Make sure your tune and wide band are set to the same AFR for stoich, otherwise there will be a huge error induced and it will throw off your data.

    If you're boosted, you may want to switch to a COS so you can get some extra tables that will help out a bunch. Read through the tutorial here: http://download.efilive.com/Tutorial...20Tutorial.pdf

    I've read through it multiple times, basically you get a VE table when you're in boost, additional spark control for when you're in boost, and some more fueling control tables. You'll need to have your laptop plugged into the car to see what COS you can flash when you open the tune tool and click on "Upgrade OS."

    Plug your laptop into your car and connect the scan tool. Look at your LTFTs and you will see how they are broken out. They should work from 0-2500, 2500-6502, 6502-6503, and 6503+. If you can't find the button, press Shift+Ctrl+F2.

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