Warhorse

I probably should have posted this in the diagnostic/tuning section but since I have a FI application, Ill try here first.

Currently running HPT 2Bar OS and OLSD. Have been tuning my self for several months with on going refinements. Weather (temperature) variations this time of year seem to require constant tweaking to maintain acceptable A/F ratio's which are monitored by WB 02.

I assume going to Closed Loop SD would allow more consistent A/F ratios during low speed or cruise regions. Cold mornings will reflect A/F ratios in the mid 13's. Heat of the day afternoons will place the A/F ratios in the high 14's to low 15's. This in within idle and cruise ranges only. Progressing into boost the readings are pretty acceptable.

In the "OL & CL" section of HP Tuners I find an option to enable STFT's which have been disabled both in my current tune and also in the stock tune for a 6.0 liter.
Can someone explain what effects would be to ENABLE STFT's ?

Zombie

iTrader: (2)

Odd, the weather should make you lean in the morning and rich in the afternoon. Is there a table that lets you tweak your a/f correction vs IAT?

I'm currently running my Z06 OLMAF since I've been having strange LTFT and STFT problems and it's been holding the a/f the same from 30 degree nights to 65 degree days the last week.

Warhorse

Zombie, Thanks for the quick response.
I'm really not sure if I have ability to adjust IATs vs A/F corrections. Some of the variations could be from heat soak as the leaner values are most notable after restarts when engine is already warm. Most definitely, my A/F readings while at idle or no load cruise do indicate somewhat richer when temperatures are cold

The option I am referring to is under the OL & CL, Open Loop, STFT Enable/ Disable section.
What exactly does this function do?

black98ws6ta

iTrader: (77)

Enabling fuel trims will try to keep the car at 14.7 during idle and cruise via feedback from the stock narrowband 02 sensors. If the tune is not close to begin with(it sounds like yours is fairly close) then it will cause more problems then good because of the big corrections.

Frost

iTrader: (45)

it's classic IAT/ECT bias tables troubles...

Turbo 6.0

Mine runs rich when it's cold then it runs at 14.7 + or - .3 as soon as the "warm up cycle" is complete. I think the table for adjusting the A/F vs IAT only goes into effect when you are in power enrichment.

Schantin

iTrader: (6)

Exactly. The stock programming highly favors IAT's vs Engine Coolant Temps. Set them to a 1.00 (1 to 1) ratio and your tune will be MUCH more stable across a wide variety of temperatures.

HOWEVER, you will probably have to retune the Ve table when you do this. I had to add in the neighborhood of 8% fueling across the board to get things back in line after adjusting the IAT/ECT bias.

You'll be good after that


BTW, you can do (in a way) what Zombie mentioned, but it's for WOT only. You can add an IAT "modifier" to the PE table for when IAT's get very high (user determined value). It'll add more fuel to prevent detonation in hot conditions.... but it's not the same as the IAT/ECT bias that will fix your problem.

That's another table entirely. it's the enrichment table (don't have my HP Tuners in front of me, as I'm at work). In short, it basically does the same thing on startup....biases fueling (start-up enrichment) vs ECT. It's set to run rich till the coolant reaches operating temp, thus the rich condition on cold startup. Modifying the values to near zero above 118 degrees and then smoothing the remaining values will do a lot to correct for this.