Ok guys, mods in sig...

I just swapped to 31#lbers and im still getting 115-120% IDC.. I changed the IFR tables to match correctly.. At WOT throttle 1st gear I am commanding 12.7 AFR and in 2nd gear im commanding 11.7.. ive got stoich at 14.68 and at 5500 + my pe multiplier is 1.148.. I cant figure out why I am only commanding 11.7 at WOT when my pe multiplier comes out to be 12.7.. I am guessing there is something else im missing.. I was thinking that the reason the injector duty is so high is because of it being fairly rich at WOT.. I am fairly new to tuning but Im learning a good bit just searching and reading.. Any info you guys could give me would be appreciated..

 

would a 255lph help?

 

If you are commanding 12.7 and getting 11.7 your LTFT's are probably high and its adding fuel when you go into PE. Sounds like you need some VE tuning would be my guess.

Edit: Just looked at the log. Course with a NB setup its a shot in the dark but it does appear to be rich at WOT. 950mv...

 

Ive got a wideband, just havent got a bung welded in yet.. i know lazy of me.. I guess I will work on my ve's this week see if that cant get it down some.. mainly just wondering why my afr wont do what i am commanding it too

 

6500rpm shifts are certainly gonna bring that IDC up, post up your tune. Your in the high 900's for NBO2 readings. Get that wideband working!!!

 

here is the tune..

i am only shifting at 6500 until i get my converter.. anything less and it falls out of the powerband after the shift

 

your maf table is almost double of what the stock 6.0maf is in your trouble areas. I am guessing you have some extreme maf values in that area.

I say, get your VE table tuned and then move on to the MAF and then work from there. (use the stickies here or on ls1tech to help you with that).That wideband will make tuning those areas a breeze.

Alot of people keep forgetting, or never know, that after 4000rpm the pcm only looks at your maf, not the ve or combo of maf/ve. As KySilverado was eluding to (eluding...hehehe) having fat ltft and then slamming into pe, you are bringing that fueling baggage with you. You just don't see the huge differences at idle and part throttle cause the pcm is "correcting" your maf overcompensation.

 

Keep in mind that in any method of fueling, SD, OL, CL whatever, what the PCM Commands and the actual AFR are not necessarily the same thing... The PCM is relying on, you guessed it, NBO2s which are only accurate in a very small range centered around stoich. The rest? Plain wild *** guessing.

Translation: get your WB02 installed before you go any further

Also, in my experience, telling the PCM to "go to" 12.5 AFR in PE mode does not equate to a commanded AFR of 12.5:1. PE is the amount of EXTRA fuel being added, not the commanded AFR (This may have changed in the two years since I've run a vehicle with PE enabled, so salt liberally).

Also, Dew is right. After 4k if you have a MAF plugged it, it is the only thing consulted on fuel calculations. Personally, I don't touch the MAF table (hehe, makes sense since I sold my maf 2 years ago ) and wouldn't with the stock MAF -- just keep it clean.

Oh yeah, once you get the tuning taken care of, if your IDC is still over 80%, you have two main choices and one ancillary choice.

1) get bigger injectors -- you can calculate how much you need
2) run more fuel pressure (which in essence, makes your injectors bigger)

A) decide that 95% or 105% is "close enough". Many people do, and that's their decision (and yours), but IMO this is a bad bad practice. If you think about what IDC means, a 105% IDC means your injectors may never close at that level -- they are being commanded open 105% of the time. Then if you think about what 95% means, and take into account the open and close time requirements of the pintel in your injectors, you are likely doing the same thing -- requiring them be open the entire time.

Think of it like this (simplified, made up numbers example). Say your injectors take .1 seconds to open or close. Next, say you are at high rpm, were each injector fires every second. If you are at 105% IDC, you are requiring the injectors to be open for 1.05 seconds, leaving .1 second to open and .1 second to close. That leaves you with 1.25 seconds between the start of one fuel squirt and the start of the next, but you need it to be every second.

Okay, so you can just limit your RPMs to stay below where that occurs (which depending on the cam and other factors may leave a metric **** ton of power unused), or you can just get bigger injectors.

 

This is why in which ever you rely on to do your calc, it's important to tune them(ve or maf). Then it's not so much guessing. If you are staying MAF, then cleaning your MAF table up can't hurt cuz what you are essentially doing is making the commanded become actual. So if you do change your commanded(after the fine tuning), you can basically bet your new commanded will be damn close.

Nice pointing this out berserk, just cuz you command 12.5 doesn't mean you are gonna get it. Hence me noticing your maf table being fat. SO your commanded is not accurate due to your maf calc. btw, I wouldn't bother with the bottom end of the MAF either, just 4000RPM+ stuff...IMO.

 

One small point Dewman --

MAF is used elsewhere too -- I've forgotten the details, but as I recall in the stock GM tune there are 'rpm boundary layers' in the fueling calcs. Something like this:

0-1800 RPM - straight VE table
1800-4000 RPM - VE / MAF blend
4000RPM+ - MAF

So, when you tune your MAF, does the AFR you call for in the PE translate to commanded AFR? If so, that makes a helluva lot more sense than what used to happen.