little LS swap help, Gen 3

Chris_Keziah said:
Not trying to take buisness from your tuner but you can drop that thing off with me 🤷🏽‍♂️

What size injectors did it have and what size did you swap in?
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If you weren't that far I would, but I don't have that kinda time. These are Summit injectors for LS1/LS3 4.8/5.3/6.0 up to 07 i think
 
marty79 said:
If you weren't that far I would, but I don't have that kinda time. These are Summit injectors for LS1/LS3 4.8/5.3/6.0 up to 07 i think
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I meant just tell your customer to bring it down here but I'm sure there's other tuners in that area.

Betting part of your issue is the fact you swapped injectors and the tune doesn't reflect that.
 
@marty79 download the tune and email it over to me curious what all they did. chris@revlimitfab.com

You never answered if you have a wideband, if not you'll need one to do any sort of fuel tuning. Goat Rope Garage has a video on how to wire in one without going through the mvpi2 unit.
 
Chris_Keziah said:
You never answered if you have a wideband
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no cause my tuning guy has all that and he's done the tuning up to this point. I mostly only bought HP tuners to disable Vats instead of paying 450 for someone to do it for me. but maybe it's a waste? idk yet lol
 
Chris_Keziah said:
Betting part of your issue is the fact you swapped injectors and the tune doesn't reflect that.
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I didn't realize changing injectors required a tune? Is it because of the 4hole vs 2hole? I mean I've swapped injectors on tons of 4.0s and never had an issue so this is new news to me, but I still have a lot to learn about the LS motors so yeah.....
 
marty79 said:
I didn't realize changing injectors required a tune? Is it because of the 4hole vs 2hole? I mean I've swapped injectors on tons of 4.0s and never had an issue so this is new news to me, but I still have a lot to learn about the LS motors so yeah.....
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If you put what I assume are flex fuel injectors in the delivery rate is going to be way higher, of course its going to need to be tuned. I know you've seen lb/hr or cc delivery ratings on injectors before, not all injectors flow the same...
 
braxton357 said:
If you put what I assume are flex fuel injectors in the delivery rate is going to be way higher, of course its going to need to be tuned. I know you've seen lb/hr or cc delivery ratings on injectors before, not all injectors flow the same...
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Ok good point, ill have to look at the order and see what they say
 
marty79 said:
I didn't realize changing injectors required a tune? Is it because of the 4hole vs 2hole? I mean I've swapped injectors on tons of 4.0s and never had an issue so this is new news to me, but I still have a lot to learn about the LS motors so yeah.....
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Just because you've always done something a certain way and never had issues doesn't mean that it's necessarily right. Injectors are sized off of flow rate, usually in lb/hr or cc/min. Most all factory truck injectors are ~25 lb/hr. If you put in something larger than that the tune will need to have it corrected.
 
Chris_Keziah said:
Just because you've always done something a certain way and never had issues doesn't mean that it's necessarily right. Injectors are sized off of flow rate, usually in lb/hr or cc/min. Most all factory truck injectors are ~25 lb/hr. If you put in something larger than that the tune will need to have it corrected.
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Yes I realize this now, just like the Intake is 4" rather than factory 3.25 so I'm sure that needs tuning, the MAF probably needs tuned in since it's not from the truck. At least the company got the Vats turned off and it runs lol, that's not worked out every time with other swaps even from reputable companies
 
marty79 said:
Yes I realize this now, just like the Intake is 4" rather than factory 3.25 so I'm sure that needs tuning, the MAF probably needs tuned in since it's not from the truck. At least the company got the Vats turned off and it runs lol, that's not worked out every time with other swaps even from reputable companies
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Did you retain the factory maf housing or did you change to the bolt in style that goes into the intake tube?
 
Chris_Keziah said:
Did you retain the factory maf housing or did you change to the bolt in style that goes into the intake tube?
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factory style with the 4" tube section that has the MAF built into it
 
The MAFS is fine. Definitely need to rescale the injector table if they're anything other than stock. Depending on which PN they are, some of those flex fuel injectors will go 40-42 lb/hr. Stocks are 26 lb/hr.

Quickest way to tell if it's dumping gas...pull the dipstick and smell the oil.
 
Croatan_Kid said:
The MAFS is fine. Definitely need to rescale the injector table if they're anything other than stock. Depending on which PN they are, some of those flex fuel injectors will go 40-42 lb/hr. Stocks are 26 lb/hr.

Quickest way to tell if it's dumping gas...pull the dipstick and smell the oil.
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Just confirmed these new ones are non flex fuel 44lb
 
Yea that motor doesn’t really need that much injector. They would probably work with a very aggressive tune
 
marty79 said:
Just confirmed these new ones are non flex fuel 44lb
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So...they're likely 8.1 Marine injectors. I have them in a very healthy 6.0. Cam, more compression, good amount of horse pressures. Max injector duty cycle is about 56%.

The only time a 4.8 would need those is with 15 lbs of boost.

Also, guaranteed the crankcase is full of gas.
 
Chris_Keziah said:
Were the factory injectors trash? If not I'd swap them back in.
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4 were bad remember from earlier in this thread when it was missingon 4 cylinders..so he bought these. Ill see what tuning guy can do tomorrow
 
Croatan_Kid said:
So...they're likely 8.1 Marine injectors. I have them in a very healthy 6.0. Cam, more compression, good amount of horse pressures. Max injector duty cycle is about 56%.

The only time a 4.8 would need those is with 15 lbs of boost.

Also, guaranteed the crankcase is full of gas.
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Hmmm, What are wiped rod bearings for 500 dollars Alex?

Sounds familiar.
 
braxton357 said:
The opposite, you can forego a tune with boost. A 4lb wastegate/spring and 67mm turbo is like $300 off ebay, will clean that extra fuel up nicely and save $200.
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Except at idle 😅 All I did was crank my truck and let it run for 30 seconds with the 8.1 injectors and that was enough to fill it with gas.
 
braxton357 said:
The opposite, you can forego a tune with boost. A 4lb wastegate/spring and 67mm turbo is like $300 off ebay, will clean that extra fuel up nicely and save $200.
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And give more woopows for free as a bonus
 
If youre going to continue this swap route as a primary. I highly recommend you move away from the flashed ECU route, and get a reseller account with holleyX, etc. Setting all the previous arguments aside made in this thread. Business 101: Efficiency.

Make sure that your Park Ground is properly grounded, it can cause the symptom you mentioned. Dont know what ECU you have, but iirc its Blue 32 pin
 
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