New LS2 swap, super rich maxing fuel trims E38

[BLAMM]

I have been doing a lot of searching and cant find a solid answer.

I have a newly built "LS2" 2008 5.3L truck block with DOD delete, 243 heads with new BTR lifters/pushrods, a mild crane cam (#1449511 descriptions states stock tune "no computer upgrades required"), 34lb injectors, ls2 intake MAF and Throttle body, with T56 Magnum Trans.

My current goal is to get it driving on its own power so I can work out suspension and drive train issues so it can go in for a professional dyno tune before any hard driving.

I ordered a new PCM from PSI conversions flashed for a 2008 Corvette Base with Manual trans giving them all the specs for stock 5.3L tune, injectors, sensors used, ect. Looking through the tune it appears they did everything as requested to my untrained eyes. Tune is attached. I can get a new log if needed.

The engine starts and runs but is very rich and maxes out the fuel trims quickly. The first problem I found is that the fuel rail pressure is at 70psi using a corvette fuel pressure regulator assembly with a high pressure/volume pump. pressure seems to hold steady even under load. Multiple regulators and research is showing that I will not be able to fix this without a new pump or running a full return system and expensive regulator.

My question is if it is even possible or safe to run at this fuel pressure if the tune is changed to reflect this? Am I able to scale the injectors to match actual flow rate and start my tune from there? Do I need to find a way to quit being a poor and get the pressure to 58psi?

[5FDP]

You will have to get the fuel system fixed, you don't want to be running 70psi through those injectors.

[blindsquirrel]

Smaller fuel pump would probably be an easier fix than changing the whole rest of the fuel system. The Corvette filter just can't flow very much through the return fitting to allow the pressure to be kept in check.

What 'high pressure/volume' pump does it have now? Do you know the flow rating?

[BLAMM]

Thank you guys. I was hoping I could just run higher pressure without damaging anything haha. The flow rating of my current pump is 50gph at 75psi. Quite a bit of overkill for a ~400hp motor. I found a Aeromotive regulator that can operate both as a return or returnless that I am going to install in place of the corvette filter for now to see if that brings everything in line before moving it to a true return style system.

[blindsquirrel]

Yeah but what does it flow at lower pressure (it will be higher as pressure decreases)?

Data is hard to find on the Corvette pump but I believe it's in the 220 LPH range... or 58 GPH. Your high pressure can be caused by anything in the return path, not just the filter-thing. Take the line off the return fitting at the filter and temporarily route it into a bucket. This will tell you if it's the filter or something in the hose or tank. If that makes a real change in the rail pressure, keep dividing the return path into smaller pieces until you find the one that makes pressure go back up.

[BLAMM]

I was able to get this sorted out but I am still left with some questions.

I installed an adjustable pressure regulator in a returnless style configuration and set the pressure to exactly 58psi measured at both the regulator by the pump and the rail. It made no change, it ran richer than hell and fuel trims instantly off the charts. Comparing my injector data from an stock 07 Corvette tune that uses these injectors I found very little deviation compared to my tune. I pulled the new set of Bosch 0280158049 injectors out and replaced them with an old used set of the same part number with the only difference of it also having the GM part number, 12569113, on them as well. Reset fuel trims and idle learn, fired right up and was finally able to take the car on a short drive down the street with fuel trims hanging out in the low single digits! Something is up with those injectors but they can get set aside for later inspection.

Still left with a few questions though. I'm not new to basic tuning or wrenching but I am new to HP Tuners and the newer generations of PCMs. I have spent hours and hours trying to find good information on something as simple as which tables need swapped with an injector change on an E38 and it is BS how little information there is out there. For instance comparing my tune from an 08 corvette to one from an 07 using the same ecm but the injectors that I currently have installed there are minor to drastic differences in: Flow Rate Mult Vs Flow, Min Injector Pulse, Offset vs Inj Temp, Offset vs press vs IGNV, Short pulse Adder, and Boundry. Which lend the most weight to calculations and need to be corrected? Which can be left alone?

[blindsquirrel]

Where did the new injectors come from?

[BLAMM]

They were in the box of parts the previous owner had for the engine, not in original packaging but looked unused. Looked like ebay purchase. They look identical to the bosch GM injectors that were already in the engine with the exceptions of the missing GM# and the nozzle was a little different. I honestly only put the new looking ones in because I thought why not.

For future reference how much of this tune file from the 2007 corvette should I be making identical in my tune since these injectors were not used in the 08 my ecm is programmed for? Min pulse and short adder seem off enough to warrant messing with.

[gtstorey]

“New” injectors are probably counterfeit junk.

[blindsquirrel]

https://www.gmpartsdirect.com/search...h_str=12569113

No results found for "12569113". Here are some helpful search tips:

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[BLAMM]

If you google search "GM 12569113" it comes up everywhere.

https://www.injectorplanet.com/produ...otors-12569113

[blindsquirrel]

If you're confident the old injectors are real and the correct ones used for the car the 2007 LS2 file came from, then copy over these 5 fields:

screenshot.01-02-2023 08.26.59.png

I did Google the number but it was polluted by so many knockoffs/scams I decided to stick to trusted sources. None of them show that old number even in the interchange.

[gtstorey]

The only site that I saw that might be credible for that 12569113 number is psi conversion and I have no idea where they get their data. But at least they aren't trying to sell the injectors.
https://www.psiconversion.com/tech/l...tor/index.html

[BLAMM]

The only site that I saw that might be credible for that 12569113 number is psi conversion and I have no idea where they get their data. But at least they aren't trying to sell the injectors.
https://www.psiconversion.com/tech/l...tor/index.html

I think the main reason that info is hard to find is that this part number was only used in the 05 to 07 Corvette and GTO. Not a lot of vehicles out there using this injector

[blindsquirrel]

GM usually doesn't completely memory-hole old numbers when they get superseded. The current part is ACDelco 2176127, with the only alternate listed as 89017586. Looking up 89017586 shows no alternates.

Just for general info, GM never uses the Bosch number in any of their published info, they do not refer to it at all. So if you do a search with the Bosch number, anything you find will be highly suspect. The scammers love to use the Bosch numbers.

2007 LS2 Vettes used the regular 33lb LS2 car injector (LS2 trucks, and lots of other non-flex trucks used 29lb 12580681(old number)/19421333(new/current number)). 2007 Vette LS7 used the 42lb LS3 injector. In 2008 all Vette engines used the 42lb'er.

You know what's even more rare than LS2 car injectors? The 2005 Vette ECM, which was a one year only thing. GM still lists the number even though it's been discontinued for 10+ years.