Tuning for 42.5 Injectors

[Wingman520]

so buddy has a 2004 Grand Prix Comp G and since i read on another forum that is more 3800 based the 3.4 pulley he has recently installed is maxing out the stock fuel injectors since his WOT is stuttering like it's choking and not getting the fuel it needs.... he has 42.5 lb lucas injectors and wanting to install them but obviously i'm the guy that needs to update his tune for this...

running the latest HPT beta 2.23.321 so i have access to Offset vs Volts, Offset vs PW vs VAC, Flow Rate vs KPA, Skew vs Cylinder for injector tables.... i know i have to change the flow rate vs kpa for the injector table but just wanted to know what other tables i'd have to change because i wasn't sure if i'd have to modify the offset vs pw vs vac table or if any other or not since i know you don't just change one table to make it work and go on about your day and think it's running ok... i'm guessing i'd have to modify the maf slightly to compensate for it as well.... thanks in advance! current tune is attached below and this is the only specs i can find for these injectors

Static Flow Rate: 42.29 lb/hr @ 43.5PSI (300kPa) or 320gm/min
Static Flow Rate: 48.83 lb/hr @ 58.0PSI (300kPa) or 370gm/min
Coil Resistance: 15.9 Ohms / High Impedance / High-Z

[danthurs]

You change the injector flow rate vs KPA and set them all to 45, save, your done.

No need to change the MAF curve unless your doing porting, changing the MAF, or it's off for some other reason.

[murphinator]

those injectors have not been characterized by anyone to my knowledge so you would be guessing on all the offsets.

to do it right you will need to have him buy injectors that are characterized as in anything that came out of a gm car you have access to the tune to grab the data , any of the ford injectors that you can get the data on Greg Banish's dvd or injector dynamics injectors as they provide full characterization with their injectors.

[Wingman520]

those injectors have not been characterized by anyone to my knowledge so you would be guessing on all the offsets.

to do it right you will need to have him buy injectors that are characterized as in anything that came out of a gm car you have access to the tune to grab the data , any of the ford injectors that you can get the data on Greg Banish's dvd or injector dynamics injectors as they provide full characterization with their injectors.

yeah i has the greg banish dvd just got it and brain hurts a lil from the knowledge i gained def worth it and now there is another one coming out this year so it's gonna be awesome... These are the ones that zzperformance sells for their lucas 42.5 injectors... cuz his IPW is like 21-22 at WOT so i know he's very close to maxing them out... i'll try the 45 to see if that'll do the trick but i might have to dig alot deeper to find out the true setup on these... that or call intense racing to see what john does for his setups on these... any suggestions for fuel tuning on IPW? or is that something i should just leave as is? thanks again guys!

**found a few tunes and a few tables i attached them below and just wanted to see if they would work/be close since i wanna get this right the first time and a few of them have a different offset vs pw vs map so should i tune that after i get the injectors installed and setup properly? also new files in original post for some IPW and offset values

[Wingman520]

well gonna take a couple paramaters from the tunes and throw those in seeing if it'll help... i know for my swap i'm gonna be doing the ford bosch green top injectors... will update when i find something out

[Injector Dynamics]

Your life will get much easier if you buy matched set of similarly sized injectors from the list that Banish has characterized.

Racetronix does a good job of matching them up.

[Wingman520]

Your life will get much easier if you buy matched set of similarly sized injectors from the list that Banish has characterized.

Racetronix does a good job of matching them up.

i did some research and the found the lucas injectors for 42.5 are actually Delphi injectors and found them on racetronix site so idk if i should use their info for these injectors if they have any to provide/what i can find... links below

http://www.racetronix.com/621031.html

http://www.racetronix.biz/itemdesc.a...1D030x&eq=&Tp=

like i said i plan on buying some from them since i see them all over this site about how good they are... i plan on getting 42.5 or even 60 lbs maybe since i plan on doing some serious mods down the road once the top swap is done

[passingpower]

I got a set of matched 42.5s from ZZP and used the Racetronix numbers in the VCM suite calculator. (I verified my rail pressure using a guage first. I re-wired the fuel pump also. makes fuel characterizing MUCH simpler on an '01 GTP)

Installed the injectors, flashed the new IFR and offsets. (researched the hell out of those) pressurized the rail and fired her up.

Idled like stock.

[Wingman520]

I got a set of matched 42.5s from ZZP and used the Racetronix numbers in the VCM suite calculator. (I verified my rail pressure using a guage first. I re-wired the fuel pump also. makes fuel characterizing MUCH simpler on an '01 GTP)

Installed the injectors, flashed the new IFR and offsets. (researched the hell out of those) pressurized the rail and fired her up.

Idled like stock.

I'll definitely try that because that was what I was intending to do... Which tables need changed for the injectors? I don't wanna miss one then throw it off

[passingpower]

Most importantly, the IFR table.
Second in importance is the pulse width vs. MAP because you're dealing with a fixed rail pressure.
And third, offset voltage. In your research you'll find opinions stating the offsets are close enough not to bother with (mostly Racetronix opinion) Others will say change it. (I agree) Still others will say there is too much variability with these Delphi parts to characterize and they should be melted down and replaced with Ford green tops or whatever.

I'm sorry I can't advise you what numbers to use because I've modified my fuel system to be a true vacuum referenced return flow system and can use a flat IFR. Because my pressure drop ACROSS my injectors doesn’t change, I don't utilize 99% of my pulse width vs. MAP table.

The only thing I can say definitely applies to your fixed pressure system (and ALL systems) is that Bernoulli’s law is strictly enforced and you should use the VCM Suite calculator as opposed to linear math.


Just to be clear, I have to agree that if you install injectors that have been RELIABLY characterized, fuel tuning will be a breeze. However, it appears your client is already married to those Delphi parts, So, charge him the cost of what he saved for you having to cope with them. As for myself, I can't charge me for making that uninformrd purchase and in the end, what I learned about fuel delivery systems during my research was invaluable and I'm glad I put myself through it.

[Wingman520]

ya the fuel rail i'm working with is a returnless system so guess i'll have to dig and see where i can find this info to enter into the tables... i'm mostly trying to figure out what to add into the offset vs pw vs vac... i've been getting a slew of possible answers... just put 42.5, put in 45 for the whole table and done so i have no idea... another person i know locally who got these injectors before he went e85 said he put 42.5 in all of the table and it worked fine but his vehicle had a gen III s/c not the gen V s/c which is on the 2004 Pontiac GP Comp G I'm working with now

[bmxer255]

I got a set of matched 42.5s from ZZP and used the Racetronix numbers in the VCM suite calculator. (I verified my rail pressure using a guage first. I re-wired the fuel pump also. makes fuel characterizing MUCH simpler on an '01 GTP)

Installed the injectors, flashed the new IFR and offsets. (researched the hell out of those) pressurized the rail and fired her up.

Idled like stock.

if u dont mind me asking.. where the hell did u find these offsets.. i am looking everywhere and cant seem to find em.. im not using the 42 lb injectors.. i just need to know where i can find the offsets for the set of racetronix/lucas injectors that i have. any help u can give me on this i will greatly appreciate.

[passingpower]

I don't mind your asking at all. Hope I can help. I used HPTuners SEARCH and Google. The website, not the forum member. Sorry dude. Anyway, search using the Racetronix and Delphi part numbers along with anything else they cross to in conjunction with "offset". In this way, I found my offsets on a competitor forum in a 2D table from an LS1. I had to interpolate my values for my simpler L67. I knew I'd never find exact numbers going into the effort because they don't exist. Explains why Racetronix can't publish them. My goal was to get close and I did that. Before my power log started cracking, it was not at all unusual to see a long term trim of 0.0 @ 625 RPM idle. When you get an answer, don't run with it. Keep looking and take the best 2 of 3 or better yet, 3 of 5. Good luck and happy hunting.