Hi.
Have a friend who swapped a 2000 5.3Vortec in a old camaro. With oem intake all okey on cold start.
But now with LS1 intake (used LS1 Injectors also) Car is very hard to cold start. and when he get it started he need to keep it on 2000-2500 rpm for a little while.
But when car is warmed up it fires straight away.
from reading 5.3vortec could have 24.8lb injectors and LS1 27.3 to 30LB injectors.
Could this be the problem ? could anyone help me ?
Thanks
Need to know what the part number is on the injectors being used. LS1 injectors could be about 4 different part numbers.
What is the fuel system? Vacuum referenced or non vacuum referenced?
Looks like no absolutely tuning was done at all on that file. It still has the 2000 Suburban's 24.8 lb injector data set up for the Suburban's vacuum referenced regulator.
Will check. But to big ls1 injectors will that cause cold start to be hard?
I think also thrittle body is replaced. But should be same diameter
U mean if fpr is vacum regulated? I will check.Originally Posted by 2xLS1
Could u help with injector change?
No one can fix the injector data, or tell you how to fix yourself, until the regulator type and base fuel pressure is known.
Will go check out the car later today.
Will do fresh read and check if fpr is vacum regulated
Have checked out the car now. Car has no vacum to regulator. Fuel pressure is around 58 psi.
Moda on car:
Orginal lm7 engine with
Med ls1 intake ans injectors
Smaller hrottle body(because restrictions here in norway)
Fpr np vacum
Ori injectors 25320288 s 3.125 gm/sec or 24.8lb/hr @ 58 psi
Ls1 injectors 0280155890 12554271 - 1997-1998 5.7L LS1 - flows 3.727 gm/sec or 29.6lb/hr @ 58 psi
He says. With ori ls1 throttlebody cold start is better.
Can anyone help here?😉
Will pay if needed😉
I'm not clear about which injectors these early LS1s used, there's conflicting info. One lookup crosses that number to one that's listed for 1997-1998 only, while another one for that same number lists it as 1997-2005. But the stock files for '98 and all the others are very different - my 1998 files have them at 28.71lb, '99-up are 26.41lb.
https://www.rockauto.com/en/partsear...rtnum=12554271 (click the blue part numbers (left side) to see the applications)
Thanks for the info.
I taught it was bigger diffrence on the injectors. But iguess a little more fuel from the injectors snd little smaller throttlebody could make it flood a little when coldtstart?
I don't have much patience for hypothesizing how it might behave with wrong injector data, what the 'normal' symptoms might be. Especially when there is no log file showing the bad cold start behavior that can be compared to a log showing a hot start where you say it does well.
If somebody can clarify the early LS1 injector number thing and which one is really used in which years so I know which file to pull from, I'll be happy to copy the injector data over into your file.
Okey. Will be perfect if we could try copying the imjector data if someone has it.
From there i can make log on coldstart. And then on hot start?
But which data from which stock files? You want to just try different stuff until you find one that works better?
I want to correct the file for the injectors to see if that helps.
So if somebody have file with the ls1 injectors u could swap that into my file if i understand ?
Ori injectors from car is : 25320288 s 3.125 gm/sec or 24.8lb/hr @ 58 psi
Ls1 injectors used on this car is : 0280155890 12554271 - 1997-1998 5.7L LS1 - flows 3.727 gm/sec or 29.6lb/hr @ 58 psi
The 1997-1998 stock files do not have the injector flow rate at 29.6lb/hr, though.
1998 files have them at 28.71lb, '99-up are 26.41lb
Yes i see they are listed with diffrent lb/hr several places.
But when i see there are so small diffrencese in lb if ori was like 24,8lb and maybe ls1 injectors used around 26 or 28lb . I dont think cold start are related to the injectors.
Could it be because a vacum fpr is removed and now its working with fpr that deliveres constant pressure around 50 -60psi ?
Or u think it could be because smaler throttle body ?
Every calculation the PCM makes that has to do with the amount of fuel the PCM is injecting, starts with the amount of fuel the injectors are capable of injecting. If you input the wrong injector data, every calculation will be wrong.
The shortest path to accurately getting this engine to do what you want is to input the proper injector data. Can you get it to do close to what you want by guessing at the data, Sure, the proof is in your possession right now. The correct way is to input the proper data, if you can't do that, mostly every other part of the tune is a guess/trial and error scenario.
If you google cold start LS tuning you will find enough info. to get you started.
I under stand what you are saying. But for me i dont have time or capability to tune it by my self. Therfor i hope someone here can help me , and ill gladly pay for a solution that fixxes the cold start problem
Contact one of the pro's that comment in the Gen 3 section.I under stand what you are saying. But for me i dont have time or capability to tune it by my self. Therfor i hope someone here can help me , and ill gladly pay for a solution that fixxes the cold start problem
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