99whitews6

iTrader: (2)

What does the PCM do differently when running SD CL mode with the LTFT enabled vs. SD CL with the LTFT disabled and just using STFT?

Schwanke Engines

iTrader: (1)

It will only correct your fuel trims on demand and not remember the cell that needed more or less fuel. So, it will be slower to react to an uncalibrated spot in the tune. Basically, the LTFT acts like a memory so if you get to that same load cell, it remembers that when you were there last time it needed x amount of correction and it adds that and then lets the stft change it if it needs to do so.

99whitews6

iTrader: (2)

Ok. Sounds good. Now, correct me if I am wrong but the MAF helps compensate for temperature changes but mainly affects areas above 4K rpms. What helps to compensate for temperature changes below 4K RPMs?

I have been running a tune in SD and LTFTs disabled. Basically I have to "update" my tune every couple of days because my STFTs are going out of wack due to temperature changes occuring outside. I just want to get back to a time where I dont have to update my tune when weather changes, but I dont understand what part of the PCM compensates for this at lower RPM,s

Or do I have this all wrong?

Rhino

iTrader: (6)

By definition the MAF is a mass airflow meter. It measures the "mass" of the air moving through the engine. It calculates this by determining the frequency at which a heated wire needs current applied to maintain a specific temperature. Temperature is one of the many things that will affect the air mass moving into a motor. Other key players are barometric pressure and humidity.

To my knowledge, the MAF is used throughout the RPM band when holding a consistent throttle position.

Schwanke Engines

iTrader: (1)

Just enable the LTFT's and it should do all of that work for you.
And yes, the MAF, when enabled, controls through the entire RPM range.