Clarification on Coyote MAF tuning

[caniggia]

You are correct if you say about sae stft, but its not working this way in sct style logging.

[AKDMB]

So how long does it take for LTFT's to be a useable correction factor per a given cell? Basically how much time do you have to spend in a cell? I like the fact that you don't have to disable anything in the tune for this method. I'm assuming you wait for an average of like 50 counts per cell?

[caniggia]

Please read my posts before. I usually dont wait long, just see what direction it goes and adjust manually, often without histo.

[txcharlie]

I did some logging on a TVS car tonight using the latest beta build and scanner. I logged stft, ltft and MAF period at steady state RPM's. Idle, 1500 and 2500. We then did some steady state RPM logging on the road. I was able to map the period and ariflow, monitoring stft and get everything within 1-2% for bank 1 and bank 2. This car also has the JLT big air intake on it. Idle improved, driveability improved, WOT looks great. Points in the trims before were 3-6% off at places.

I would say this is a success.

So you used the LTFT+STFT/2?

[wbt]

So you used the LTFT+STFT/2?

No sir. I just monitored ltft as a sanity check. All changes made were based off of stft's.

[txcharlie]

Either way should work, STFT's with LTFT's disabled, LTFT's only, or average of STFT+LTFT's, you're applying the fuel trim error% anyways to the MAF period, to derive your MAF curve according to what the fuel trims are adding/removing from your fueling in close loop.
Positive LTFT's should indicate the pcm is adding fuel, cause you're running leaner than stoich, negative LTFT's would be the opposite, PCM is removing fuel as you're running richer than stoich. STFT's work exactly in the same way, they just happen to move a lot faster cause there is no history to build from like LTFT's. if you have LTFT's enable, why worry about what the STFT's are doing ? once in close loop, they'll be the closer to stoich you can be, with LTFT's enable, just look at LTFT's and forget about STFT's.

Thanks for the input. When I heard that STFTs were the correction factor, I thought "hey that's simple" and was using it only. Then I noticed where it was lean and I corrected it, it was now rich by a large margin and I began to wonder what was going on and so began my quest to find out what method everyone was using.
It makes sense to me that LTFT would give a larger sample and should produce a better average for the correction.

[txcharlie]

No sir. I just monitored ltft as a sanity check. All changes made were based off of stft's.

My first corrections were from idle/rev logs and those corrections seem to be spot on, but when I started doing cruise logs, I was getting large (5-9%) STFT corrections in the cells I had already changed from the idle/rev logs. That's what made me start to question the method.

[txcharlie]

I appreciate all the input guys!

[wbt]

My first corrections were from idle/rev logs and those corrections seem to be spot on, but when I started doing cruise logs, I was getting large (5-9%) STFT corrections in the cells I had already changed from the idle/rev logs. That's what made me start to question the method.

It helps a bunch now that we can log MAF period and airflow together.

[AKDMB]

So just to reinforce my understanding of. using LTFT for MAF correction.

1. The LTFT is basically already a record of consistent STFT corrections for a given cell.

2.They get more and more precise over time as the PCM spends more time in a given cell.

3. When using LTFT nothing needs to be disabled to avoid "chasing you own tail" during the MAF tuning process. Less of a chance of screwing anything else up in the tune.

4. Just make sure the car is all warmed up and ready to go before you start to try to dial in anything, or you will chase your own tail.

[caniggia]

5. Use ltft only if stft are close to 0.

[AKDMB]

5. Use ltft only if stft are close to 0.

Can you explain? Real noob here, but I feel like this thread has been very informative.

[caniggia]

That means you need to wait some time to ltft get stabilized. Thats why tuning using ltft only is not good, every tune write, they are reset.

[Exley]

Can you explain? Real noob here, but I feel like this thread has been very informative.

I look at STFT first (right after a flash so that the long terms are cleared) STFT is an instant correction. How much fuel the computer is adding or removing right now to get to stoich. You need to dial that in first or your long terms will be all over the place trying to make huge corrections both negative and positive. You want to get your STFT as close to 0% as possible. In reality you should shoot for 0-5% + or - because conditions are always changing, like the weather.

LTFTs are learned FROM the STFT. If a short term is consistent enough it will be saved as a long term and the STFT will start from that point. This makes the short terms quicker to react since they are correcting with the LTFT already factored in.

Once you feel you have short terms dialed in you can drive the car as you normally would for a few days. After that log the long terms and look for parts of the maf that are more than a few percent rich or lean. Sometimes when you dial in the short terms there are conditions that you were never able to log that use that same area of the MAF. You'll start to see these trends with the long terms and can farther dial in your part throttle.

It helps to have your STFTs already dialed in so that you are getting consistent data for your long terms.
I still consider myself quite the noob myself, but hopefully this will help you.

[imsuperman]

I apologize for asking on this thread but would anyone know the airflow limit on the stock Coyote MAF? I seem to be flat lining at 86lbs on the datalog so I'm wonder if I'm hitting a limit. Thank you.

[AKDMB]

That's the limit

[txcharlie]

(#/min x 10) is a close estimate to the HP the engine is making at the flywheel. I think you are hitting the limit of your 10# pulley.

[imsuperman]

(#/min x 10) is a close estimate to the HP the engine is making at the flywheel. I think you are hitting the limit of your 10# pulley.

It's only putting out 620HP on the dyno. Can I rescale the MAF Transfer?

[txcharlie]

Is your MAF Period working on the log? If so, you can check you period against the #/min to see if it's close.
Coyote uses Period in place of AD counts for 3vs.
And dyno's lie.

The car I used to have showed 86#/min on a M6. It made 672 at the wheels on a Dynojet.(In very cold 30* air)

[imsuperman]

Is your MAF Period working on the log? If so, you can check you period against the #/min to see if it's close.
Coyote uses Period in place of AD counts for 3vs.
And dyno's lie.

The car I used to have showed 86#/min on a M6. It made 672 at the wheels on a Dynojet.(In very cold 30* air)

My MAF period doesn't work on my OS yet. I do have the HZ on the SCT log that I guess I can convert.