Thread: Rebuilt everything and I need some guidance. (Injectors,gears,e-85)

Originally Posted by 01Blackgtp

I am coming close to getting the car re-assembled, and i'm not sure what to enter into this HP tuner magic box before turning the key. Also have never used the tuner yet, it just got here today. Rebuilt TEP trans with 3.29's #65 deka injectors intercooler 1.9 rockers p&p blower with a 3.0 pulley slp headers AEM wideband Stock cam....for now. I understand the gear change is an easy edit to a single box, but what do I need to change for the injectors? I looked over at the HP tuner board but the link to an injector spreadsheet is dead. Im just looking for someplace to start with the larger injectors I dont think I can just fire the thing up with twice as large injectors than it had. I went with the really big ones in hopes of tuning for e85, and I already have the fuel pump rewire and Tahoe filter in place.

I can send you some injector flow data that should get you started with those 65#ers. I'll attach it to this thread later today

Originally Posted by 01Blackgtp

Pulled the file from another car with the 60's in it and looked at the IFR vs KPA table and the numbers across the board were way higher 58 to 61 across the table. You sure it should be 42-45?

Was that car running pump gas or E85?

Originally Posted by 01Blackgtp

Right, now I understand, and I am clearly an idiot. The 58-61 table is for 60#s on pump gas the 30% increase from that would be the 42-45. The numbers work backward from how I was thinking it should.

Still learning what all these tables and numbers do.
What about pulse width? does that need to be changed anywhere?

I just installed 60's this morning on my GTP and only changed the IFR table. Here it what the table looked like:

Throttle%: 0 10 20 30 40 50 60 70 80 90 100
Fuel Flow: 62.0 62.9 64.0 65.5 65.9 66.0 66.2 66.3 66.4 66.6 66.9

Didn't touch PW or anything else. Seems to be doing just fine. Minus the fact that my fuel trims are all over the place at the moment until I get into PE mode.....

whats youre FPR 43 or 58psi?

Originally Posted by 91parkave

whats youre FPR 43 or 58psi?

I just have the stock one that came with my 99 GTP.

It's important you know your rail pressure you should be right at 48-52 ish of rail pressure for a gtp. Which of course would dictate your injector flow rating.


Try 63.2 63.9 64.8 65.3 65.0 64.5 63.4 62.7 61.8 61.6 61.3

Originally Posted by 91parkave

It's important you know your rail pressure you should be right at 48-52 ish of rail pressure for a gtp. Which of course would dictate your injector flow rating.


Try 63.2 63.9 64.8 65.3 65.0 64.5 63.4 62.7 61.8 61.6 61.3

Interesting. Is it normal to have the numbers in a decending slope relative to pressure as shown? I just went for a good drive and fuel trims seem a bit more reasonable now (still high though). I was thinking about subtracting 1 or 2 from the entire table...

Originally Posted by 97AutoXVette

Interesting. Is it normal to have the numbers in a decending slope relative to pressure as shown? I just went for a good drive and fuel trims seem a bit more reasonable now (still high though). I was thinking about subtracting 1 or 2 from the entire table...

Exactly youre slope was meant more for a steady state returnless system since your a return style and also under boost your IFR will be a little diffrent.
Id also load in the injector offsets and see where that takes you, Id highly recomend always starting off the injector data per manufacturer inserted. Then you do what you have to do, but atleast your foundation is right IMO

Originally Posted by 91parkave

Exactly youre slope was meant more for a steady state returnless system since your a return style and also under boost your IFR will be a little diffrent.
Id also load in the injector offsets and see where that takes you, Id highly recomend always starting off the injector data per manufacturer inserted. Then you do what you have to do, but atleast your foundation is right IMO

appreciate everything. Some good info, and I was unaware of how the FPR functions in this case between when the engine is in vacuum vs boost. I'll upload the IFRs you mentioned above this afternoon and see how my trims look. I'll post some results to this thread later today or tom.

thanks again! (Feel like I am totally thread jacking at this point. Sorry op!)

Originally Posted by 01Blackgtp

No its good info, i'm copying numbers down too!

This is a pretty interesting article:

http://www.hptuners.com/forum/showth...ector-IFR-help

Talks a lot about when flat vs. skewed IFR tables are used, and why. Some parts are confusing, but overall, a good read!

p.s.. Last night I scaled my 33# (36) stock injectors up to my new 60s by just multiplying the stock table by 60/36. Fuel trims are much more reasonable now (+/- 5%) and seems to be running well. I'll be logging more data to see how it does as the week goes on, but figured I would share that approach!

I had quite the headache getting my 50#s figured out.... glad you got somewhere though for now.

Originally Posted by 91parkave

I had quite the headache getting my 50#s figured out.... glad you got somewhere though for now.

Did you ever end up changing anything besides IFR by chance? Not sure if I should consider gain/offset as well, etc.

Originally Posted by darkhorizon

stock injectors are 33#

Thats what I figured but when my LTFTs were high, figured I would make my IFR table a bit smaller and see what it'd net me.. I also saw something on ZZP's site suggesting some call the stock injectors "36lb injectors".. Not sure where that is rooted though