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DD fell off the wagon

Handsome Jesus

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yeah send me some more. and someone tell me why after 50# injectors and E85, and an IFR table scaling, my car is running consistently lean to the point it trips the CEL.

IFR was done as follows (with DHP) 36#injectors(33.7#)/50#injectors(50) = .674

E85 -> .674*1.33 =.89642 scale factor

I feel like something is wrong, because I dont think the tune should be off THIS much... also, a pulley change from a 3.4 to a 3.2. typically resulted in slightly higher maf readings at idle and cruise, but nothing like +16 LTFTs constantly, and up to +30 in VE tuning mode.
 

Ron Vogel

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I never rely on just the math...it never works out. There are far too many variables in play for it to work. Get it close with the math, then move it in either direction by percent to dial it in. Best off removing as many variables as you can (hint: don't use the MAF)
 

Handsome Jesus

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Thanks for the help ron. What I'm still concerned about is if the math is even right. if in fact I need to do it the other way around (50/36) and then multiply by the 1.3xx.

The VE tune we did last night eventually evened out to around the right place, though it did go to -5ish ltfts at the end of the night. it started at +30 though... should we have done something differently instead of just modifying the VE?
 

TommyGloves

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yeah send me some more. and someone tell me why after 50# injectors and E85, and an IFR table scaling, my car is running consistently lean to the point it trips the CEL.

IFR was done as follows (with DHP) 36#injectors(33.7#)/50#injectors(50) = .674

E85 -> .674*1.33 =.89642 scale factor

I feel like something is wrong, because I dont think the tune should be off THIS much... also, a pulley change from a 3.4 to a 3.2. typically resulted in slightly higher maf readings at idle and cruise, but nothing like +16 LTFTs constantly, and up to +30 in VE tuning mode.
Now that you mention it, I had the same problem back with my 55#s and thought WTF. I added in about 10-12% at the time to the IFR table and it got the trims back under consistent +16.4. I also noticed that my MAF curve changed overall after doing some MAF tunes after adjusting the IFR table. Like Ron mentioned, the math didn't work at the time. :dunno:
 

Ron Vogel

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Thanks for the help ron. What I'm still concerned about is if the math is even right. if in fact I need to do it the other way around (50/36) and then multiply by the 1.3xx.

The VE tune we did last night eventually evened out to around the right place, though it did go to -5ish ltfts at the end of the night. it started at +30 though... should we have done something differently instead of just modifying the VE?
I personaly wouldn't mess with VE unless you are 100% on the ifr being right.

The corn juice's specific gravity is different than gasoline, and also varies from station to station. This is not just from the supplier, but also because of evaporation. Always be tuning on alcohol for weeks, it will never be perfect...get it as cose as you can. If you leave a container of rubbing alcohol open overnight, how much wil be left in the morning?

Same thing happens in your fuel tank, as well as the gas station's tank!

My method isn't perfect, but I don't think there is one sure-fire way of doing it...it's always a frustration. Take a good gas tune, add 30% to the IFR table and set the max timing to 22-24 for WOT. Unplug the MAF, then dial in the IFR table over a week of driving (limiting WOT). From there you can see an average in IFR values enough to determine a trend to carry through the WOT values (I like to graph).
 

Handsome Jesus

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yeah I was about to say... I haven't fiddled with timing at all yet. this whole extremely lean mixture is turning me off right now.
 

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I don't know what your problem is here, scale the IFR table for those injectors as if it was on gasoline, take the table and add 33% (gets you close) and you're done. Phat's car took us like 15 seconds including turning on the laptop. All that bs math you're doing up there is just confusing you, it's so much easier than that. :dunno:
 

Handsome Jesus

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well the math above is what I was using to scale the injectors, unless my procedure for scaling them is wrong. What would you use as the scale factor for 50# injectors? I have the 33% part factored in like you said there. I was also under the impression that it was that easy. that's why this all has me thrown off a bit.
 

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hmm... I don't know how you pt guys scale your IFR table for bigger injectors.
 

TommyGloves

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hmm... I don't know how you pt guys scale your IFR table for bigger injectors.
I think that might be the problem. Staight up math (33%) did not work for me either in PT. I'll post up my 55# table later tonight when I get home.

DD - What specific injectors are you running?
 

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I found that using too low of timing on corn doesn't do anyone any good. It likes to be right at 22, but some cars can run up to 24 if they are set-up right. If the car can't handle 22 degrees at WOT, then boost needs to come down a little, or there is a fuel delivery problem. Corn is slower burning than gas, it needs more timing than gasoline. Now if you have bumped compression then definately bump it back, but on a 3800 (L67), 22 is the sweet spot.
 

Handsome Jesus

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they are delphi 50# High Z injectors. or at least thats what the guy I bought them from said they were. they are flow tested to each other, but show nothing by means of what they actually flow.

http://www.racetronix.biz/itemdesc.asp?ic=17113738&eq=&Tp=

that is what they look like. I did read somewhere that Delphi might make 42.5# injectors that look the same? if that is the case I'm gonna be pissed.
 

Handsome Jesus

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well the car has a walbro 255 and zzp pump rewire, running through stock rails into the 50# injectors. fuel filter is not too old, but I wanna give the E85 time to dissolve some shit before I change it out later this week.

S1x cam, mild heads, pacesetters, 3" exhaust, stock Gen 3, ported LIM, big intake, and just put the 3.2 on at the same time as the injectors... If that helps
 

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I think that might be the problem. Staight up math (33%) did not work for me either in PT. I'll post up my 55# table later tonight when I get home.
Weird... On phat's car it worked absolutely perfectly, seriously took like 15 seconds.
 

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