3.75L Build thread

[green-lantern]

made a video of 2 step or launch control or whatever you wanna call it. it was extremely spur of the moment, but figured i would post it up. both of these revs built 12psi. i am too nervous to hold it out longer haha

That's scary awesome lol

[futurevr4man]

as far as im concerned, you will see it in real life in a week haha

[futurevr4man]

so i had a bit of a eureka moment today: i am an idiot (honest mistake)

so when i had my old build (3.1L and 19t's) i was tuning using an safc2 and old school maf-t to tune with. i had the maf-t set for the correct size injectors, but otherwise zero'd out, and used the safc for the fine tuning. worked great.

well fast forward to this engine and i had 550's in it initially and i was still using the safc and maf-t. well when i did the flashable swap, i kept the maf-t so i could use the bigger z06 maf and i thought i had set everything to 360cc injectors and all zero'd out. well i zero'd out the base, idle, mid, and high (wot) knobs, but guess what? there is another knob... the aux knob.

i had this bad bear set on "9" and then the base was set on 0. that equals 490cc injectors. guess what? 490cc /= 360cc injectors. for those that dont fully understand the maf-t, ill briefly explain it. you tell it that you have some size of injectors (whether you actually have that size or not doesnt matter) and it intercepts the airflow signal before it gets to your ecu, and 'changes' your airflow signal.

SO in my case, 490cc injectors (instead of the 360cc stock size) means that it is going to register a lower aircount. can i tune around it? yeah, i can... and i more or less did. however, because of less airflow, there is less load, which puts you in different fuel and timing tables etc etc. this ONE THING has been mainly what i have been fighting all along. so now, after finding this, and just laughing about it at this point, the car tuned SOOOOOOO much easier lol. i was seriously like sweating, thinking im an idiot or something, because things were not so great. my lean spot is gone, my timing is better, my airflow is WAYYYYY out the roof now, and i am overall much happier. the car pulls better too.

here is a quick pic of a log i took tonight. you all should be able to follow it, but for the lazies, 80% throttle, working my way to a nice 10.5 AFR @ ~6500 rpm's and 3400 HZ hahahahaha. thats more than maxxing the limitation of the ecu lolol. AND this is all at 16psi



greg, i am curious why i can go higher than the 3200hz limit? or is it that i can only control up to 3200hz? no resolution beyond that?




so with all that being said, i hope to turn the wick up, and really start making some nice numbers very soon. the car pulls darn good for 16psi, and i know my turbos havent even begun to breathe.

i made a very quick video of a launch. i am going to show it just because, i promise it is nothing special. the video quality seems lower than normal, not sure what happened. and fwiw, i am spinning, not bogging.

[Greg E]

There is no 3200 limit. The code keeps going.

You control the range with your 4 knobs.

[futurevr4man]

ah - i see. i am anxious for V2, so i can get some resolution way up high!

[Blackmount]

nice launch vid! car sounds awesome.

[Greg E]

ah - i see. i am anxious for V2, so i can get some resolution way up high!

Now that I'm sober (well... Hung over anyway) I can comprehend this better.

First off: told you so. (that MAFT was reporting way too low of airflow)

Second: damn you for being me to 3400hz!!!

Third: Pay close attention to your wideband. If that starts going lean, that means you reached the limit of the ECU! I honestly don't know where that limit is!

What can you do now? You can slow that airflow signal back down on the MAFT and compensate with the tables. By slowing the signal down (setting your global injector size to something larger or even just lowering the high knob) you essentially give yourself more range within the 3400hz.

If you keep revving beyond 6400rpms does the airflow still keep increasing?

I'm wrapped up in the new custom pin chrome mods at the moment but after that I'd like to get on the phone with you to do some experimenting.

[futurevr4man]

bahahahaha, what did you drink last night?!

first: yeah yeah yeah, suck it trebec! i never doubted you for a moment

second: pfft. i am not even pushing much boost yet. you and your schmeepy 9b's muhahahaha

third: why does this make the work around obsolete? i thought you said you had effectively figured out how to double the the hz range?

and yeah, i learned a lot yesterday due to this discovery. stupid aux knob. so, currently, the maf-t is zero'd out on idle, mid, and wot, and its set to 360cc injectors with the aux and base knobs. and i know if i give a couple of clicks on the base, i can up them. i have the word doc from fullthrottletech on my comp at home so i can semi-strategically scale the airflow.

assuming i hit the limit of the ecu, is it going to go incredibly lean, or is it just going to run off of that last value at the 3200hz spot on the VE table? in otherwords, keep a VE value but keep increasing airflow, which will cause me to steadily get leaner? i assume the latter, but figured i would ask. i knew i would be the one to start pushing the limits of your code first, but until yesterday couldnt figure out why my car wasnt running like it should be.

one more thing, am i correct in assuming that the better i scale my airflow, the better my tune will be? what should i try and keep my aiflow peak below? that 3200 limit? the airflow reading changes so many things, that its going to be key to dial it in.

[Greg E]

I edited my post while you were writing yours:

It doesn't look like you hit any limit yet. When you max out the log, it'll just repeat the same number over and over. Doesn't look like that is happening.

When you reach the end of a table, the ECU just uses the last segment in all calculations larger than the axis. So from 3200 and up, it uses that last number.

[futurevr4man]

ok, then my assumption was right on the VE table... thats what i figured. thats why it says 107 in my log, which makes sense.

and idk if it keeps increasing, that and the launch were the only two time i really got on it. i havent revved it out yet. i mean, it goes into mid - low 10's way up high, so i usually pull out of it. i was mainly tuning partials all evening yesterday.

btw, when you turn off closed loop feedback, is it supposed to run really rich when the engine is cold? i figured due to the coolant temp factor it multiplies by, it would make sense, but it wasnt this bad when i had closed loop turned on