LTFT at -10 at idle

[punkwrock]

I had problems with my lftf's being at -14 with sri and tip. So i took everything off and the car is now bone stock with a bone stock factory map. Plugged in my AP and at idle i was at -10.2 ltft. When i drive it stays between -2 and +2 which is perfect. But when i let the throttle go to shift, it drops back to -10 until i touch it again. Suggestions on what this may be? i've been looking on the web alot, but i only seem to find people who have problem with high ltft's compared to low.

[punkwrock]

People where saying that i needed a maf cal....well obviously if everything is stock now and it's still doing it, there's something more than a maf cal behind this.

[fywdyl]

Absolutely stock? Maybe you need to tighten things down? If not then def a MAF cal.

[punkwrock]

Yup! Everything is absolutely stock....and i mean everything. i really did tighten everything down well. And when i took off my sri and tip, everything was clamped down solid too. But why would i need a maf cal if the car is all stock? You would think that it would come off the line with everything working properly.

[pwdunmore]

Yup! Everything is absolutely stock....and i mean everything. i really did tighten everything down well. And when i took off my sri and tip, everything was clamped down solid too. But why would i need a maf cal if the car is all stock? You would think that it would come off the line with everything working properly.

All cars are different, calibrating it just makes it more accurate. Tuning your car requires more exact measurements I am assuming. Right now my LTFT is at -6 at idle. I have my SRI on. Trying to figure out the calibration procedure now, I need to meet up with someone to talk about how to do it properly. I know in the PDF help guide it says it should be +-8% so I am good with my current settings just wanted to know how to do the calibrating. I am surprised that your numbers are outside of mine and I'm not on stock anymore :S

[loki]

mudda***kah you could have posted this in the other thread

I don't see why you needed to create another thread.


all we need now is silverstarmazda to come in here and talk about MAF calibrations and how a squirel was once sleeping in his engine bay which caused the car to run hella lean


f****

[punkwrock]

http://www.youtube.com/watch?v=zwtcp53fAlA
Check this link out. 6 part video on how to maf cal. Extremely helpful. My LTFT's are good during the drive....it's just during idle. So i'm gona try callibrating that first. Baby steps.

[loki]

I had problems with my lftf's being at -14 with sri and tip. So i took everything off and the car is now bone stock with a bone stock factory map. Plugged in my AP and at idle i was at -10.2 ltft. When i drive it stays between -2 and +2 which is perfect. But when i let the throttle go to shift, it drops back to -10 until i touch it again. Suggestions on what this may be? i've been looking on the web alot, but i only seem to find people who have problem with high ltft's compared to low.

-10 LTFT means your car is pulling 10% fuel at idle which means that the MAF thinks it is getting 10% more airflow than it actually is.

I hope you at least figured that out from your extensive reading

[punkwrock]

Yeah i'm starting to figure all this out i think. So when your LTFT's are running in the minus, your AFR's should be richer correct?

[loki]

Yeah i'm starting to figure all this out i think. So when your LTFT's are running in the minus, your AFR's should be richer correct?

No, since in closed loop the car will use feedback from the sensors to correct the AFR. That is the whole point of the LTFTs. It is pulling 10% fuel so that your car will hit targeted AFRs

[punkwrock]

So by pulling 10% fuel....you mean the ecu is sending 10% more fuel, or cutting back 10%....sorry for the idiot in me here. But i want to learn.

[loki]

So by pulling 10% fuel....you mean the ecu is sending 10% more fuel, or cutting back 10%....sorry for the idiot in me here. But i want to learn.

in your case its negative 10% so it's cutting back 10%

if it was a positive LTFT the ECU would be adding fuel to compensate for the excess airflow

[loki]

I'm going to bed

you should go read. Like Horto mentioned in your other thread (which is where all this shit should be as well), read the Cobb help file

It is very long and very technical. If you dont find it interesting, you shouldnt be tuning or messing with your own car. There are pros on here that will do that for you for a small fee

[punkwrock]

so in a nut shell, my Maf things it's getting 10% more air than it actually is, so it's cutting my fuel by 10%

[punkwrock]

So to fix my idle, i would have to check at which MAF voltage it goes to the say -7.8 for example. find the break point of it and take 7.8 divide by 100 which gives0.078. The i would take 1 and substract 0.078 from it which is 0.922. i would take the 0.0922 and multiply it in the maf tables where needed right

[fywdyl]

When you took off your Sri and tip did you reflash the stock map?

[loki]

So to fix my idle, i would have to check at which MAF voltage it goes to the say -7.8 for example. find the break point of it and take 7.8 divide by 100 which gives0.078. The i would take 1 and substract 0.078 from it which is 0.922. i would take the 0.0922 and multiply it in the maf tables where needed right

yes, but if you do that without smoothing your curve, you'll have a very harsh drop in MAF voltage where you stopped applying the correction factor and the car does not like that....


so in a nut shell, my Maf things it's getting 10% more air than it actually is, so it's cutting my fuel by 10%

the horse is dead....


When you took off your Sri and tip did you reflash the stock map?

I say chances are high that the answer is no

[pwdunmore]

This is the part where you send your logs and get a custom map tuned for your car :P loki just made my head explode...

[Fack_Dude]

Here is one piece of advise for you wanna go fast wannabes. Mspeed tuning.....lol

[punkwrock]

Yes the map is flashed to complete stock mazda map....still have a -10 ltft at ifle

[horto]

Here is one piece of advise for you wanna go fast wannabes. Mspeed tuning.....lol

+1

when you hit that point of diminishing returns vs. personal time invested on your journey of self-tuning... at some point it just makes more sense to get an mspeed tune.

[punkwrock]

Well i reinstalled my corksport intake and inlet pipe which made my ltft's go back to the -15 range at idle. -15,-10,-7,-5 ended up being my ltft's at my different breakpoints. After numerous convo's on speed forums, we came to the conclusion that there aren't any leaks as a leak would cause positive fuel trims. Anways, i did perform a maf cal and got it to be between -2/+2. Took some 4th gear WOT logs and everything is A1. Just thought i would give an update, so that if anyone else has such ltft that is that much in the minus, your car might just not be aggreeing with the OTS tune as mine did.
thanks!

[loki]

Now you need to calibrate your MAF for WOT

You can do that based on the 4th gear log by comparing the ratio between actual AFR vs commanded AFR


You also need to find the point where you car typically transitions from closed loop to open loop.

Anything before the open loop transition gets calibrated using LTFT readings, while everything after uses the AFR readings.

The transition point is when LTFTs begin to read as -0.16 in your logs. You need to take a bunch of logs to get a good idea how accurate the MAF is in open loop WOT

[loki]

Example if at 2.0 load, you are commanding an AFR of 11, but your logs show you are hitting 10.5, it means that the MAF is reading more airflow than it is actually getting so the car runs rich. You need to reduce the MAF voltage by that ratio:

Actual AFR/Commanded AFR x MAF Voltage

So in the case of my example, 10.5/11 = 0.9545, so multiply that voltage by 0.9545

Obviously you need to apply a generalized value along your MAF curve and you don't want sudden jumps in the voltage