Nistune Forums

KA24DE

What is this?
Is there an ideal number or percentage that you wanna be at?
Is this some sort of fuel trim learn?


Is this related?


If so I think this would be a good way of confirming or dialing in your k constant? yes or no?

Also found this I though was interesting, have you seen this before:

http://notes.ump.edu.my/fkee/e-Books/Au ... er%202.pdf

Thanks
Sorry for all teh questions

I also have a suggestion, the way Nistune shows the numbers or (values) and percentages of the AF Alpha Learn (LHS) seems to be backwards:

Should they show like so below:

0 <> 128 <> 255 = value

+100% <> 0% <> -100% = # of Percentage

For instance in play back mode, the player displays 0-255 as percentages........shoudn't it show +100% threw -100% as the percentage?

Either way 0% or 128 value should be the the goal or target to reach right?

I've heard of people using the trims to check K value but I've never used it myself. Could be worth looking into!

I tend to just set the low load values in the fuel table to "0", turn O2 sensing off and adjust K until AFR's are around stoichiometric.

PL

I have been playing with this alot more lately and I like it. Basically yoru combination of Injection Multiplier and Injection Latency determine your fuel trim and ofcourse you need to have a good working NBO2 sensor.

This really seems to help getting good throttle tip-in when you get your fuel trim to "128".

I have spoken to other guys who use this as an indication of how close their K constant is to right. Makes sense. Must start using it myself....

PL

im a nissan tech. That diagram is given 2 all techs on a magnet u put on ur tool box after u finish obd2 class. And r obd2 certifide. It's sole porpus is long term short term fuel trim and keeping the cat happy, but it's not gonna give you power.
It helps find drivability problems: bad airflow meter, fuel pump, intake air leaks, bad injector.

im a nissan tech. That diagram is given 2 all techs on a magnet u put on ur tool box after u finish obd2 class. And r obd2 certifide. It's sole porpus is long term short term fuel trim and keeping the cat happy, but it's not gonna give you power.
It helps find drivability problems: bad airflow meter, fuel pump, intake air leaks, bad injector.

and incorrect Latency and Multiplier settings, I notice the car just drives alot better in closed loop with more "perfect" fuel trims, but it is ignored in open loop. I find it helps with gas milage also. I guess it could also help you diagnoise individual injectors problems to.

Found this good read, even though its OBDII its still appplicable I think.

Thank you very much for the PDF!

More good material

Yes this is good info

You will notice I've renamed AF Alpha / AF Alpha Learn in the latest versions to short term and long term trims and added this to the consult panel. I've also added these gauges to some earlier model vehicles like RB30ET and CA18DET

Basically from that document, adjust your K such that STFT is close to 100% and reset your LTFT (using the Active Test - Clear self learn feature) before making adjustments

I'm putting some info together on the VE map side of things also in updated documentation since this is dependent on the Add Fuel (Alpha/N) TPS table

Matt wrote: Basically from that document, adjust your K such that STFT is close to 100% and reset your LTFT (using the Active Test - Clear self learn feature) before making adjustments

PL wrote: I tend to just set the low load values in the fuel table to "0", turn O2 sensing off and adjust K until AFR's are around stoichiometric.
PL

I was always doing K like Pete teach us in early documentation, so is STFT just method for "fine" tuning of K or should we continue to use old method and just use latency to get STFT to near 100% ?

Yes, I tend to still set K the same way and then monitor the fuel trims throughout the tune, tweaking the latency to give good idle mixtures and try to get fuel trims neutral.

Should be easier now that Matt has put L/STFT on the gauges panel. So we can keep an eye on them throughout the tune.

What we're trying to avoid is having the fuel trims affect the tune once it's complete.

PL

So if we get STFT near 100% it will have smallest affect on tune?