1-why are Prediction Coefficients zeroed out and 2- Why are LTFT dissabled on tunes

Ok,

So for the past year I keep seeing more and more tunes from other shops where the tuner is zeroing out everything under the

Airflow--->Dynamic----->
Prediction Coefficients: Base, Current, Old, Corrected, Cam Transient, MAP, MAP Old1, MAP Old 2, TPS, TPS Old1 and TPS Old2

I found some information where people say to zero them out on cam cars and others that say not too. I'm hoping people can post their reasons and thought process behind their approach.


Also, I keep running into tunes where tuners disable LTFT and solely rely on STFT to make any fuel trim adjustment once in CL. Again, I'm looking to understand why tuners do what they do.


Thanks in advance.

Roger

I’m hopping this doesn’t go in answered for a long time. My thoughts are these topic items are still classified under the top secret file for tuners or I just do it because they do it.

1: I can tell you for my e67 Gen IV ECM, PE fueling showed lean spikes and was not controllable until I zeroed all of the prediction coefficients. This only was the case after I installed my cam. VVE and MAF were each perfect by themselves, but once combined things were problematic. Zeroing the prediction coefficients fixed all of that. I would assume it is a similar situation on a Gen V controller, but I have no personal experience with a Gen V

2: Some people like to dial in fueling really tight and let the STFT take care of all disruptions (bad fuel, aging narrowbands, etc). It also prevents LTFT from adding to PE fueling when LTFT are positive. In my opinion, it is better to leave them on but many feel the opposite and tune with STFT only. I prefer to get LTFT into the -2 to -5 range so they don't influence PE, but are still there to keep things in check as needed.

My answers are not based on Gen V experience, but since you weren't getting any answers, I thought I'd provide at least some feedback for you.

Thanks! Very insightful information. I’m sure it relates. Thanks for pulling back the vail of secrecy lol

Have a gen 5 file and all those maps are there as well.

Do you leave the prediction tables set to zero when done tuning? Was thinking that if the MAF and VVE were set right, predictions would be a good thing for the environmental factors, to compensate for them. The conflict in my thinking is if I am tuning, I am telling it what to do based off the sensors. So do I even need the predictions when I'm done?

This assumes I understand the "predictions" are a tune-able thing....meaning I'm guessing. Can you elaborate some more?

https://forum.hptuners.com/showthrea...n-Coefficients

https://forum.hptuners.com/showthrea...ine-separately

https://forum.hptuners.com/showthrea...ransition-Lean

Hey, thanks for the links. I've got some reading to do!