JHForman

After I tune my VE table in open loop do I turn on both LTFT and STFT? The reason for the question is, I can tune in open loop and get my afr error to +/- 2% and also my WOT fueling to the same, but once I turn the LTFT and STFT back on my fueling seems to be way off am I missing something ? I don't believe LTFT or STFT are used for WOT but I'll have -12% error in some cells that were just fine prior to turning them back on??!!

Ken in AZ

Are you tuning with a wideband? And yes STFT should be turned back on, LTFT's some people like to keep them off as they can creep in and mess with the tune sometimes - personal preference.

Atomic

iTrader: (42)

I trust the narrowbands a whole lot more than the wideband.

Last Call

iTrader: (4)

I would recommend turning on your trims, the STFT's at a minimum. STFT do not affect WOT fueling. LTFT can affect WOT fueling if they were positive when you went into PE. If you have -12%, I would consider doing a free air calibration on the WB02.

Is it -12% across the board, or just in certain cells?

JHForman

Lol of course I have a widebamd, anyone who would hang a turbo on a truck and try to tune with a narrowband is gonna get what they deserve. How long does it take for the LTFT to settle in? I tune the whole VE table up to 100kpa @14.7 in open loop, then when it turn my PE back on its right where I want it 11.2-11.4 after that I am tuning everything beyond 100kpa to 11.2-11.4 making adjustments to the VE table this is how I understand it should be done? Set the PE to the desired afr, go floor it and adjust VE table and do it again(I have my VE set pretty rich so I'm usually taking away fuel). And I'm not making changes till have at least 300 hits in each cell(this is costing me a lot of fuel lol). But once I turned on LTFT and STFT my fueling looked terrible the -12% was just an example of a cell it was the highest of them all. The rest were 4-8% roughly .

Atomic Performance

You have a wideband, do not ever disable PE or BE when you have access to a wideband.

300 hits is way more than you need.

Do not "floor it", slowly roll into the throttle to prevent transient fueling issues that skew your steady state results.

The time it takes LTFTs to become active depends on the amount of correction and time of correction from the STFTs. I wouldn't not recommend using LTFTs while you are activing tuning, it just makes it more complicated without adding value. When you are completely finished, then maybe, but there usually isn't a need at that point.

If you would like more personalized help with tuning I will be happy to help

madmann26

iTrader: (7)

Tune non PE/BE with the STFT's. Once you get your VE to +-1-2%, like Atomic said, roll into it easy and watch your AFR's. Adjust. Rinse/Repeat.

Turn the LTFT's off imo.

Set PE to 12.5 AFR and BE to 11.2-.4 (whatever you prefer) AFR at 135KPA. The PCM will use the richer of the 2 values.

TrendSetter

ive been driving olsd on my truck at ~15 psi for like 3 years now and at about 30psi in my evo on 93 for about a year.
my evo is my primary daily. its been spot on ever since i disabled closed loop. before that the tune was a mess. same with the pickup.

Atomic Performance

If closed loop doesn't work then either the sensors are bad, or you have a bad exhaust leak. As long as the PCM and sensors are getting good data, closed loop control works extremely well and is very stable.

lbz34

iTrader: (3)

Open loop and closed loop both work great, just depends on what you prefer, some vehicles I leave in closed loop and some I leave in open loop.