fuel trim adjustment

[pearl4gtsi]

ok, yes another fuel trim question, but this is to ensure i understand everything i just read.

just got mmcd. been checkin out the fuel trims and doing some reading. my current trims are:
low: 81.2%
mid: 100%
high: 100%

now i know that the low trim is rich and the other two are good, but i havent seen any movement from any of them. i know mid and high dont change as quickly but i havent seen the low change? am i not in closed loop?

also, i want to adjust the low trim to be at or near 100%. my mods are up to date.

my maf-t is setup up to just the injector size, but the other knobs were left alone so i could tune mainly with the s-afc. but ive read that using the low mid and high knobs in the translater adjust airflow in hz? and could i theoretically just adjust the low knob in the translater to get my low fuel trim where i want it to be??

 

[-red97rum-]

Yeah you can do that but I always found it easier to use the safc since it's in the car and you can change it on the fly. Give it some more time, the other two fuel trims should start to make adjustments.

 

[pearl4gtsi]

yeah, thats what ive read. was just toying around with it today after doing some work and i got my low fuel trims where i want them by adjusting with the s-afc. i took away alot ofcorrection, -24% to be exact, but its good. thnx

 

[-red97rum-]

I remember having to make a lot of adjustments too. Even though the maft claims to "set injector compensation" , right... Every car reacts differently and you'll have to tailor your tune to your specific setup and environment.

 

[pearl4gtsi]

yeah, i knida figured it wasnt going to be exact. and it was much eaiser to adjust with the safc. got all the trims at 100% and the car is driving like a dream. just have to tune for my wot. any suggestions or words of advice red?

 

[-red97rum-]

yeah, i knida figured it wasnt going to be exact. and it was much eaiser to adjust with the safc. got all the trims at 100% and the car is driving like a dream. just have to tune for my wot. any suggestions or words of advice red?

Sure, carry the "lo" settings on the safc over to the "hi" setting but add 4-5% on top from your spool rpm (like 3200rpm for 16g) on up to redline to be safe. Turn your boost down a little bit and go log a 3rd gear wot pull. If it pulls clean with no knock or hesitation/sputtering turn the boost up a little at a time, do another log etc. I liked to run it rich up to my desired boost level, let's say 20psi. Then slowly lean out the safc until you get nice, smooth, hard pulls. If you start to see knock then add fuel to the rpm point where it's knocking to quench it. You can also set your base timing a little retarded (2-3*) to help combat knock.

Is the AFR gauge listed in your profile a wideband? It would be nice if you could set it up in MMCD to log the wideband. If not, just keep an eye on it during your pull to make sure you don't go too lean. Set up the alarm feature in MMCD to beep at you when you get 4-5 counts of knock. If it knocks during your pull let off the throttle and review the log to find out why it's knocking. Then you have to determine if you're knocking because of being lean or being too rich. Usually if you're registering knock from being rich the car will also be breaking up and sputtering up top. If it's knock from being too lean the car will be pulling nice and hard but feel like little losses in power here and there when the ecu pulls timing. Be careful, lean is mean.

 

[pearl4gtsi]

no, i do not have a wideband. that is next on my list though. right now i just wanna get used to tuning with what i have and learn as much i can. since i got my base setting down, the car feels great!!

need to work on my wot still. going to play around with it today. because im using the stock narrow band, what kind of voltage do i want to see in boost? ive read anywhere between .8-.9v is ideal.

two quick qeustions. one, i still run my stock 14b. got it running at 18psi. isnt that the highest youd want to boost that turbo, or will it take more. keep in mind its the stcok turbo with like 140k on it.

two, the 14b spool up starts at what, like 3k? just so i know where to start to richen it up.