LS2 Swap - Injector Confusion

[the300zxmaster]

I have been reluctant to make this thread, and hope I don't get burned too terribly bad. I have not been quite able to piece together an answer to my "problem" and keep getting confused and turned around backwards. Thanks in advance

Once I get home I will post the base tune file I am using for reference.


Essentially I want to verify I am entering the proper values for the injector data. .
FLOW RATE VS. KPA
OFFSET VS. VOLTS. VS. KPA


Injectors are GM#12569113, which from my research I believe are (34#) @ 58 PSI
411 Blue/Red PCM

I am utilizing a returnless style fuel rail regulated by the corvette (no vac reference) style filter. To my understanding this unit should maintain constant pressure 58 PSI.


This is where I begin to get mixed up and backwards. Logic tells me that the flow rate vs. kpa should be 34 across the board since there is no reference, and in theory fuel pressure should be a 58 PSI constant.

I would assume this same theory for the volts vs. kpa. It would seem to me that you would want the same values under the column of KPA which achieves 58 PSI to be copied to all columns.

Regardless, it would seem acceptable to use the injector data from say an 06 LS2 Vette.

Once again, i will post my current base tune this evening for reference.


Someone please smack some sense into me.

[the300zxmaster]

Here is the base file.LS2-Base Tune.hpt

[the300zxmaster]

I have attached the updated tune based on a stock 2005 vette. I have the older PCM so the scaling is different. I did my best at matching the values, but am not confident at all. I have also attached a log file after i made adjustments.

Lots and lots of learning to do.


Any and all responses welcome

[schpenxel]

Logic tells me that the flow rate vs. kpa should be 34 across the board since there is no reference, and in theory fuel pressure should be a 58 PSI constant.

No. At the injector tip, it's not constant. The flow rate table should not be flat across the board. It will only be flat when you are using a vacuum/boost referenced system

When under high vacuum the fuel pressure at the injector tip is effectively higher. Say, 10psi of vacuum, 58psi fuel pressure = 68psi fuel pressure at the injector tip. Think of this as vacuum "sucking" fuel out of the injectors, effectively increasing fuel pressure.

When close to 0kpa vacuum it would be 58psi

If you were in boost it will actually reduce effective fuel pressure as manifold pressure is pushing back on the injectors. 6psi, 58psi fuel pressure = 52psi at injector tip.

I think about it this way: if you were running 58psi of boost and 58psi of fuel pressure, would any fuel come out of the injectors? Nope, it wouldn't.

[the300zxmaster]

Thank you for that explanation!!!! Now i can get on with business, haha.

I entered the values from a stock 2005 vette as mentioned above, but the scaling is different due to the PCM it would appear. I got the tables to mach as closely as possible, but would be awesome if someone could look at what i entered to give me some advice.

[schpenxel]

Post both tunes and I'll check it out

[the300zxmaster]

Post both tunes and I'll check it out

Awesome, thanks!

[the300zxmaster]

Here is a short log. PE is rich

[the300zxmaster]

Afternoon bump for advice

[schpenxel]

Awesome, thanks!

Looks pretty well the same to me

[schpenxel]

You're getting some weird AFR oscillations when @ WOT especially. It's not staying smooth at all

What's the latest tune look like?

It's weird, inj PW is pretty stable in some spots but AFR is swinging from 15:1 to low 11's. Doesn't make sense

[the300zxmaster]

You're getting some weird AFR oscillations when @ WOT especially. It's not staying smooth at all

What's the latest tune look like?

It's weird, inj PW is pretty stable in some spots but AFR is swinging from 15:1 to low 11's. Doesn't make sense

That log was using the tune from post #7.
I too find it odd. I am not sure what would cause such a sever swinging AFR.

[the300zxmaster]

The MAF reading appears to go quite jumpy under WOT as well if i am not mistaken.

[schpenxel]

yea but not that bad