Quik

iTrader: (7)

was out loggin beastmodes truck. since last time i touched his truck he has done LTs and dual 3" with X side exhaust [my old 408 exhaust]. did a good bit ot tweaking and truck woke up greatly...now heres the old thing

last log i did before this his IDC was 105 tops, today during 1st and 2nd it was 138% and in 3rd it was 120%...what you think....yes he needs injectors thats a given but i wonder if his stock fuel pump is also causing this... truck is ls1, 224 cam, truck intake on stock injectors....i was thinking of selling him my 255 pump setup. didnt check psi either so not sure if its dropping or not

but 138% is high as hell. i have never seen a IDC that high

TouchOfEvil04

iTrader: (13)

Not sure how the pump would cause high IDC.....Seems the fuel just woudn't be there at all if it was the pump.
Guess if it's slowly goin dead it could be though?
I know myself and DLH2006 did our swaps at around the same time and we both had IDC of about 115% or a little higher in any gear from like 5200rpms and up.
I doubt any of this helps you at all but i felt like rambling.
On a side note once we both did the 8.1 marines we both dropped down to the 60's from our IDC's.
I'll have to see what it's at after i instal the heads this weekend....my month long instal thanks to work haha.

Quik

iTrader: (7)

i dont even think 30s will do much for this setup. now a set of svo 30s would work out best.

you get duty cycle from restriction in fuel system or injectors. its just odd that a gain of 20 bascially from headers and more aggressive tune

TouchOfEvil04

iTrader: (13)

We both went to the marines....42lbers.
If it went up that much i'd start checking stuff though. Unless it was just at the point already ya know.

TouchOfEvil04

iTrader: (13)

Any chance a fuel line got pinched during a header instal or something like that?

truckmann

iTrader: (8)

Ya I don't think you can tell anything about the pump from IDC.... Anything above 100% IDC is just a theoretical calculated number anyway since it is impossible to run an injectors past 100%. Most injectors have unpredictable flow characteristics above 80-90% IDC anyway.

KySilverado

iTrader: (7)

Fuel pump if fuel pressure falls off.

zippy

The IDC is commanded, but isn't directly fuel pressure related. The pcm assumes that the pressure is fine and commands XXX% of IDC. If the fuel pressure were always low it would have high LTFT's which would add to the IDC issue, but if the LTFT's were anywhere close to zero, fuel pressure drop shouldn't affect the IDC.

As for injector choice, I'd just go with the marine 42's.