Tuning LTFT's...

[Junior1683]

whats the easiest way? im running real rich and i wanna get it close to 0. ive looked but my car its lb's/min and everything else is g/sec.

thanks!

btw its for a grand prix

[Moonbiter]

Sorry I don't have the answer, and I was getting ready to ask the same question, but I do have a question for you.

How are you monitoring your injectors? I wanted to monitor the duty cycle to see if I'm beginning to max them out out or not but if I can see what lb/hr they are doing I can live with that. What sensor and/or PIDS you using? Do you have a gauge set up for it?

[Junior1683]

no 1 here has tuned their fuel trims? wow

[5_Liter_Eater]

Tried reading any of the stickies? Whats the easiest way to tune my LTFTs is a rather general question. We're not here to spoon feed you, asking specific questions is more helpful.

[Junior1683]

yes ive read. i was wondering if there was an easier way than using the fuel trim tables and my maf numbers.

"In the scanner under Table it will have a bunch of different things listed, find out what your Mass Air Flow is at idle (lb/min.). In the editor go to Airflow->General Airflow->Airflow vs. Frequency. Find the cell closest to your value, select it and a few around it (about 4 on each side) and multiply them by a small amount, since you want MORE fuel, say 1.05 (I explain what I did to subtract fuel later, but it's probably obvious ). Then select a few frames further on both sides of what is already selected (for a total of about 6-7 on each side) and click the little green button right above the 2000 that says "smooth selection" when you scroll over it. Then write the tune to your VCM and repeat the process, let the car idle for a few minutes and see what the LFTF's are. When you get them closer to 0 you can go in smaller increments, say multiplying by 1.03. When you get them around -2 to 0 you are in good shape. "

thats what i was sent

[5_Liter_Eater]

OK, there are indeed easier ways to do it. I've never tuned a V6 so I hope everything I say applies but it may not.

You need to make the histograms work for you. Set up a histogram that plots LTFTs against the MAF table. Just drive around, trying not to enter PE because when you enter PE fuel trims lock out so any data in PE is no good. You are only able to tune part throttle with LTFTs. Post a tune and a log and I can help you with the histogram. Once you have the histogram all you need to do is take the data you collected and copy and paste it (paste special, multiply by %) into the actual MAF table. Reset your fuel trims and repeat, the fuel trims should be closer now.

Post a log and a tune and we can make some real headway.

[Junior1683]

ok sweet. i gotta install my ported TB tomorrow and then ill get some scans..

thanks!

what do you want me to scan for?

[5_Liter_Eater]

Just do a quick scan, all I want to see is what PIDs you are logging and are capable of logging.

[Junior1683]

this is usualy what i scan for:

engine RPM
Vehicle Speed
Throttle Pos.
Ign Timing Advance
Knock

Mass air Flow
Manifold Pressure

Engine coolant
intake temps

delivered trans torque
current gear

O2 voltage
injector pulse width
total missfires and what cylinders
Long term Fuel trim
Air fuel ratio command


thats what i have set up to scan for..someone mentioned having to scan for something different instead of the MAF to get the histogram to work right?

[5_Liter_Eater]

Depends on which MAF PID you mean. You need to be logging MAF Hz not MAF g/s in order for the histo to work.

[Junior1683]

ok i can scan for that..ill do a scan in a little bit. still waiting on my gasket for my TB

[Junior1683]

you got a PM

[Junior1683]

here it is. i think thats the tune i used. i went back to square one because of the ported TB

[5_Liter_Eater]

Sorry, can you post your config as well?

[Junior1683]

i think this is it?

[5_Liter_Eater]

NM, just import this histogram into histo 8. It plots the LTFT's against the MAF table.

This is my V6 ignorance but are there two O2's? You are only logging one O2's mV and LTFT.

I'd whack the misfire PIDs to increase the logging resolution.

The fuel trims look to be pretty good to me already.

[Junior1683]

ok so its opened in the scanner and i got a bunch of numbers...now what?

do you have AIM or yahoo? so much easier

[5_Liter_Eater]

All those "numbers" represent the fuel trims at the different MAF Hz. So if you take your log and plug it into my histo you see that @ 2250 Hz you have a +6 fuel trim. Multiply whatever number you have in your MAF table at 2250 Hz by 106%. The easiest thing to do is select all from the log and paste special, multiply by % into the MAF table in the tune. Flash, reset fuel trims and do another log, the fuel trims should be better. Once you get close you should start doing paste special, multiply by % - 1/2.

Not 100% sure about the V6's but the whole point is to get the fuel trims ~0 or preferrably slightly negative. If you have positive fuel trims then when you enter PE it adds extra fuel on top of what you command.

[Junior1683]

how do i reset the fuel trims?

[Junior1683]

i got it!! thanks!!! they read 16.4 on start up for a few mins and then sits at 0..thanks!!