Vortec 454 Injectors

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454C2500Longbed

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My truck has the dreaded hot start issue and it left me and my buddy stranded at Culver's last weekend. Came back a few hours later and it started right up and drove home, but started stumbling when given consistent throttle, it would come and go. Anyway, I know it needs injectors and I am seeking some advice on what I should get. I looked through the Official 454 thread and found a couple helpful things. I did a search on google and of course ignored all the 80 dollar set injectors, though my cheap a** self wanted to get them. :rofl: I found this set from SouthBay, which seems pretty reputable and what really caught my attention is how well they dial them in. https://www.southbayfuelinjectors.c...firebird-305-tpi-southbay-fuel-injectors.html
They're close to the same fuel flow, so my hope is that (if they fit) I can throw them right in without having to tune, but still have a little bit of room to tune when the time comes. I need to keep digging to try and find the measurements for these injectors versus the stock ones, but anyone else know them offhand? And if any of you guys have recommendations for better injectors (or ones that will fit haha), please let me know. I'm looking to spend about 200 bucks for a set, and have them ideally be just a little higher flow than stock so they'll be fine without a tune right away. Future plans for my truck are a moderate cam, egr delete, headers and cutouts. Initially I was thinking Blackbear tune, but then I'd have to wait until I have all of those things done and it's not often I have a completely open weekend. I've also considered just spending the sh*t ton that it is and getting the tuner and software, I think I was leaning towards HPTuners but I'm open to suggestions. I don't yet know how to tune, but I'd be more than willing to learn if I can get more out of my truck that way. I'd really like the ability to tune the truck whenever I put on a new performance part, but it's that price that is boggling my cheapness. Any input is very much appreciated!
 

df2x4

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I think I was leaning towards HPTuners

What year is your truck? If it's '98+ the PCM is supported by HPTuners and EFILive. If it's '96-'97 then the only option I'm aware of is JET DST.

Also I'm no tuning expert so someone else can probably speak on this with more authority, but IMO swapping in different sized injectors with no tuning (even if they're close to stock) probably isn't the best idea.
 

454C2500Longbed

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What year is your truck? If it's '98+ the PCM is supported by HPTuners and EFILive. If it's '96-'97 then the only option I'm aware of is JET DST.

Also I'm no tuning expert so someone else can probably speak on this with more authority, but IMO swapping in different sized injectors with no tuning (even if they're close to stock) probably isn't the best idea.
It's a 96. I was not aware of that, I should look into that then.

Yeah, you're probably right. Though, I believe the ECM is able to learn and correct for incorrect fueling via the upstream O2 sensors?
 

454C2500Longbed

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You are correct, I'm not sure why I thought HPTuners was compatible. There is a pretty good deal on the JET DST right now, $460 shipped so I'm considering that, but I don't know if I should drop that much at the moment.
 

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It's a 96. I was not aware of that, I should look into that then.

Yeah, you're probably right. Though, I believe the ECM is able to learn and correct for incorrect fueling via the upstream O2 sensors?

That's not the right way to do it. From the factory they already have a bit of negative trim. Going to a bigger injector can run the risk of maxxing that out, it can only trim to a certain extent. Get some LS1 injectors and have the injectors flow changed in the tune to account for it. And then enjoy everything else about the tune. You have no idea how much power is on the table with just a tune.
 

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Yeah, you're probably right. Though, I believe the ECM is able to learn and correct for incorrect fueling via the upstream O2 sensors?

That's correct, but this correction only occurs while the system is operating in Closed Loop operation.
(O2 A/F feedback loop mode) In English, during cold start/warmup mode the system is running purely
off of the factory stored tables, so the ratio of original vs new injector flow rates is pretty much how
far off you'll be. A few % difference like you are proposing isn't necessarily a show stopper, but a
large step change would certainly goof up the first part of every drive.

On the other hand, if you were to join this forum's Saturday Morning Tuners Club, your proposed injector
upgrade will help you to unlock the real potential of your big block. (The factory tune *is* conservative,
so that it will work from New Zealand to TX to Sweden, and all points in-between. :0)

And Supercharged111 is correct to caution you that the amount of allowed A/F correction is finite. It may or may not
work for you in your case, depending upon how all your other variables stack up.

By the way, congrats on your good taste in powerplants. When you put a sharp tune on that 454 it will
feel like you are driving downhill with a tailwind pretty much 100% of the time. For yours truly it is deeply
satisfying to be swinging more hammer than what the job requires. :)

Good luck, and be sure to let us know what you discover.

PS: Welcome to the GMT400 forum!
 
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454C2500Longbed

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That's not the right way to do it. From the factory they already have a bit of negative trim. Going to a bigger injector can run the risk of maxxing that out, it can only trim to a certain extent. Get some LS1 injectors and have the injectors flow changed in the tune to account for it. And then enjoy everything else about the tune. You have no idea how much power is on the table with just a tune.
Fair enough, thank you for pointing that out. I'm furiously researching right now to find some affordable LS1 injectors, do you have any recommendations for something that won't break the bank? I don't know if I really want to spend the money, but a bunch more power for little more than computer work does sound quite alluring. I know you have quite a lot of experience in tuning with both of your supercharged trucks, so I'd love to hear whatever information you'll give.
 

Supercharged111

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Fair enough, thank you for pointing that out. I'm furiously researching right now to find some affordable LS1 injectors, do you have any recommendations for something that won't break the bank? I don't know if I really want to spend the money, but a bunch more power for little more than computer work does sound quite alluring. I know you have quite a lot of experience in tuning with both of your supercharged trucks, so I'd love to hear whatever information you'll give.

I also have a not supercharged truck that's dying for a tune. It's a 99 454 Vortec with the same hot start issue. It has a 60 second delay on PE fueling, so basically no PE ever and NO timing at WOT. Thing is absolutely nutless in its stock form. Why not get some used stock LS1 injectors? Last set I bought I paid $40 for. I'm thinking of snagging some NA series ii 3800 injectors for this 454, I know I can get the correct injector flow rates from HPT and plug those into EFILive. They're just a hair bigger than stock. Of course the temptation to mix and match stock injectors is also there as I have 8 on the shelf from when I upsized the dually injectors.
 

454C2500Longbed

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That's correct, but this correction only occurs while the system is operating in Closed Loop operation.
(O2 A/F feedback loop mode) In English, during cold start/warmup mode the system is running purely
off of the factory stored tables, so the ratio of original vs new injector flow rates is pretty much how
far off you'll be. A few % difference like you are proposing isn't necessarily a show stopper, but a
large step change would certainly goof up the first part of every drive.

On the other hand, if you were to join this forum's Saturday Morning Tuners Club, your proposed injector
upgrade will help you to unlock the real potential of your big block. (The factory tune *is* conservative,
so that it will work from New Zealand to TX to Sweden, and all points in-between. :0)

And Supercharged111 is correct to caution you that the amount of allowed A/F correction is finite. It may or may not
work for you in your case, depending upon how all your other variables stack up.

By the way, congrats on your good taste in powerplants. When you put a sharp tune on that 454 it will
feel like you are driving downhill with a tailwind pretty much 100% of the time. For yours truly it is deeply
satisfying to be swinging more hammer than what the job requires. :)

Good luck, and be sure to let us know what you discover.

PS: Welcome to the GMT400 forum!
Ah, thank you sir for explaining how that works. Good to know!

I will probably have to do that then, where might I find that?

Yeah, I spose I'd rather be safe than sorry and this does make a pretty good case to buy the tuner and do it myself instead of get a mail order tune.

Thank you sir! The 454 is what sold me on the truck, I just had to have it! Ooh, I'm pretty excited now. For what it should be, it is quite anemic stock, but it still lays rubber when I step on it at a light. The bigger the better, I always say, and you can never have too much power!

Appreciate the welcome, I love it here already, there's just so much to know and so many cool people.
 

454C2500Longbed

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I also have a not supercharged truck that's dying for a tune. It's a 99 454 Vortec with the same hot start issue. It has a 60 second delay on PE fueling, so basically no PE ever and NO timing at WOT. Thing is absolutely nutless in its stock form. Why not get some used stock LS1 injectors? Last set I bought I paid $40 for. I'm thinking of snagging some NA series ii 3800 injectors for this 454, I know I can get the correct injector flow rates from HPT and plug those into EFILive. They're just a hair bigger than stock. Of course the temptation to mix and match stock injectors is also there as I have 8 on the shelf from when I upsized the dually injectors.
Mine is about where yours is at, it does not have the horsepower it should when I stomp on it, but the torque is there down low. Hmm, that's not at all a bad idea, the flow matched thing was the only thing tugging my strings about buying new. But I have no problem buying used, so I might just search for a good set. I was looking at getting those 3800 injectors as well, I just couldn't find em in anything but a set of 6. Do you have any experience with JET DST or do you use EFI Live exclusively?
 
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