Doubtful, all Injectors where cleaned and flown 300 miles ago and no signs or smell of fuel in the engine bay.

 

possible your injector scaling is off since you freshened them up?

 

I know the scaling is off, but why would my STFT be 0 and my LTFT be -6?

 

stft affects the ltft ... the pcm has learned over time to pull 6% of fuel from idle. STFT is used as an immediate compensation for variations in the environment.

Say you had a constant running average of -7.0 STFT ... eventually the LTFT would start to consume that information... LTFT would start to build and in turn STFT would start to decrease its compensation

 

Gotcha, Yup my primaries are much higher than what they should be 400CC/min compared to 290CC

 

I'm almost 100% sure. The scaling on injectors in atr is flow at pressure. I think the whole reds are rated at 290 IS MM Bull ****. Red injectors are 330cc. And 369 IS the flow rate at 4 Bar. So if yours are flowing 400 at 58 PSI then they are flowing about 8% more then stock.

How much have you adjusted your MAF by? 2% would be my guess then the other 6% is being taken care of by the LTFT.

 

Just a rough example Logan, I was simple stating they flow more than they normally do. I have to do the math but I follow the injector bank scaling procedure and just increase or decrease the size based of the % my trims are off and verify.

 

Carbon, I figured it was a good thread to post that in. I haven't watched any of the videos, but If you know your injectors are off then I think you should fix them before you adjust your MAF scale. or Set them to correct then adjust the MAF to bring your LTFT into the right range.

If you don't know for sure then adjusting based on MAF is a good thing.

 

STFT should only go and stay at 0 in Open Loop. This is typically how you see where the transition occurred in the log. In closed loop it should be constantly changing, usually around + /- zero unless compensating for changes

 

Team is correct.

If the car isn't warmed up it'll be in open loop and that might account for your STFT being 0. It's a thought.

 

I say 0 but it was fluctuation between -1 and 0

 

STFT = Short term fuel trim
LTFT = Long term fuel trim

 

I'm with logan. Scale your injectors before touching the maf.

and good explination paimon.

I love this thread. I've been looking for a place to discuss tuning ideas openly on this platform.

 

Looking at ATR, Bank 1 is 369, which you stated is at 4 bar/58PSI. Bank 2 and 3 are 476. My injectors where flow rated at 400 (reds) and 420 (yellows)

So my bank 1 is 7.75% larger but my bank 2 and 3 are 11.76% smaller.

Last time tuning I just did the logging and adjusting by the differential of fueling vs AFR Target and AFR Actual, would it be a better start this year to adjust my injectors by the change in flow rate before I do anything or follow the same procedure as usual but be aware they will change once i get to that step?

 

If your MAF is flowing at 5-5.5 g/sec then change injectors; and vice versa.

If they are flowtested and you want to change them ahead of time, I don't see why that would be a problem - I do that currently. Just be sure they were flow tested at 60PSI - lots of places only do it at 30 PSI.

 

This is a side note but really goes for anyone who is looking to tune:

1. watch the videos
2. trial and error

I learned a lot from Kane and went from knowing nothing about tuning to getting a foot in the water and a tune from him that worked.

One of the hard parts from me though was really understanding, and i mean REALLY understanding exactly what happens when certain things are modified. So now that the weather is nice out, and the days are longer, i decided to go back to my stock tune, and put everything that I learned to the test.

I am happy to say that after a day or so of tinkering, i have an awesome idle (maf reading 5.5g/s ) with about a 0%avg stft, and each rpm range from 3k - 6k is averaging right around 0%stft... no long term trims at any location. My WOT pull is looking pretty good...need to scale back my secondaries a bit because im just about 2% lean trending on the top of the rpm band (averaging about 12.1 in areas that i targeted 11.8)

All that aside. dont be afraid to try things out when scaling. My fear is what really drove me away from learning, and honestly, it was amazing to look at some data and say 'oh ok, this is this, that is that, so i need to scale my maf/primaries by X%' and low and behold you see that math properly play out when you go to acquire a new set of logs.

As long as you are changing things that you are unclear about ever so slightly, and capturing data, your risk of harming the engine are so low. Fun example was my CL band was trending about 5% rich (~-5stft across the board to 6k). Well i scaled the injector down instead of up (negative sign threw me off). What happened ? Turned on the car and now i saw ST's sitting at -10 ... awesome ... i just learned something.... did anything break? nope ... did i quickly realize what i did wrong? yup!

So all I am trying to say is ... and I am 100% guilty of this ... sometimes it makes more sense to DO and LEARN from the results, than ASKING and PLUGGING and not UNDERSTANDING

*steps off soap box*

 

don't be too worried about chasing down 0 LTFT as seasons change so does weather and temps and the LTFT will change to accommodate that.

 

So this may sound pompous (and I apologize if it does), but is tuning really just about scaling your MAF, Injectors, dial in your AFR under WOT and timing? For some reason thought of it as some non understandable voodoo magic.

 

****, I attended the class, downloaded, converted, edited and watched the videos probably a dozen times now and I'm still lost.. Lol

 

You will change your attitude if you ever tune for boost.

 

I am not saying I know exactly how to do the things I listed, specially talking full advantage of timing etc... just saying that those are the basic principals and issues that are focused on. knowing what to change is only opening the door, knowing how to change them and why is the separation point.

Probably never will

 

it's pretty simple once you understand the concept and how all the parts work together. Timing is where I fail at life. This platform in particular is rather simple in the tuning dept. I also am N/A and haven't ran into any real problems.

 

MAF scaling vs Injector scaling first is irrelevant, you really have no idea which one may or may not be accurate and are guessing regardless to start (maybe both aren't ...)

for most people I'd recommend scaling your MAF first ...

 

So this would be a bit of a learning experience for me, as well as others....

how would one deal with something like this? ...

So as we can see, the maf is scaled. I'm reading about 5.5g/s idle (1.16v) ... Idle's average trim is -0.87 (average of lt/st). but then we get an interesting sweep of posi trim, a blip of negative, then pos, then neg.

So obviously scaling the injector wouldn't really make sense ... does one muck with the maf curve, or are these numbers close to the threshold that one would just say 'screw it - close enough'

 

idle LTFT -2 under throttle it goes to -6 does LTFT change over the period of tuning or should it stay the same. worked with Kane getting the car where its at. and we were at 0 for LTFT, after things looked good and drove the car for a period of time the LTFT stay at -2 and WOT or load its -6.