sine much has been made about roughing out your fuel maps to the olumetric effiency of your engine, i.e. like a LT4hotcam equipped one moving the powerband up in the range obviuosly :-)

I now idle in gear at about 55-65kpa and in park about the 50-55 range, and almost all of my under 2500 cruise rpm is wayy rich in the 100-108 or so blm range...

Can i make "semi gloabal" changes to chunks of the fuel map as my roughing in guide? I have quite a lot of diacom data logged already in around ton driving , idle at various rpm, idle in gear, and quite a few constant road speed logs as well so i have more than enuff to get me started on my merry way...

trying to rough in as much as possible as quickly as possible due to the fact that i get horrenous mileage and the fact the my ve is rich enuff, that my cold starts suck and its only about 40 here in the mornings lately and it cranks for 3-4 times then fires , also tends to stmble when cold for the first mile or so...

Please let me know your opinions on this and/or how u guys tend to rought in your ve curves..I do have the 730 part throttle tuning article printed as a reference(and about 40 others lol) and am just looking for ways to shoot me into the ballpark and so please feel free to speak your mind :-)
thanks
jeremy
PS get my proms it happens t-nite :-)

 

IMHO the only way to really do global type fuel trims is based on the injector constant. However, this can be really tricky. If you are rich in the idle portion due to lower VEs then IF you raise the injector contant to lean it out then you will be leaning it out everywhere. I would not do that. In this case I would take the time to dial in the VE appropriately for idle. This way you won't screw up your fueling in the higher kPa regions .... ESPECIALLY important for boosted engines because you do not want to run lean and detonate.

Tim

 

Trax,
that was exacty my intentions:-)
have quite afew idle both in gear and park logged and using them to hopefuly dial in my actual idle itself..

but like i said in my earlier post at almost everywhere in the lower ve curve below 1600 that i can find and well inot the upper ve curve is in the 100-110 blm range ..and suffice to say im sure u can imagine what its running like lol not as bad as i would think, but sure as hell no where near optimum lol :-)

was going to work in the lower ve table idle and lower and the lower spark tables(correspondingly) abd get the idle close to hopefuly optimized(i know it wont happen over nite)

but the lower ve is so much off almost consistently at all part throttle lite cruise below 75mph(high as ive logged) that im serioulsy tempted to pour thru all of my data and divise an avg multiplication facotr for it, especially at the lower ve(kpa) regions

the consisteny of it is whats leading me to do this and at least get my blm slighlty more acceptable.... and one in on the final result

thanks for the time
jeremy

 

You are on the right path. Definitely take the time to just tune in the lower curves. Been there done that :-D With a 230/245 cam my lower VE curves are almost half what the stock TPI is. It took some time but its well worth it.

BTW - Like you, I devised a way to do this a little easier. I developed a program for the $8D that accepts a Diacom file and averages the BLMs across the spectrum. This makes it a little easier to fine tune the curves. Automating tasks like this is the way to go. Maybe eventually I will end up writing code that not only averages the BLMs but also calculates the new VE and automagically inserts it into the BIN ... one day ...

Tim