Hanging Idle On LQ9 Swap

[Travis7109]

I'm having this hanging idle issue and I can't figure out why it's doing it. In the log all I did was a quick throttle blip. But, as you can see, it took forever for the engine to idle back down. Any input would be appreciated.
Tune: Firebird Current 5-10-2025.hpt
Log: Firebird 5-10-2025.hpl

[blindsquirrel]

Well starting at the beginning, the foundation every other calculation is built on top of, the injector data is wrong:

screenshot.10-05-2025 18.12.38.png

What are the injectors?
Where did they come from?
What data are you using for the injectors?
What is the fuel system & regulator type?
What is the fuel pressure?

[blindsquirrel]

Also: the filenames say Firebird but the OS is from a Suburban; what is this vehicle? Is it a swap/standalone type thing in an older vehicle? Or a PCM & engine swap in a LS1 car? What are we working with here? You know it inside and out, we don't unless you tell us.

[RDF1]

Add Throttle follower airflow and IAC Position

[Travis7109]

ACDelco 12613412 50LB injectors.
91 octane
vacuum reference return style system
regulated to 58psi.
I pulled the injector data from a forum post for that injector part number.

It’s an LS swap in a 1979 Firebird. Stand alone harness with a factory ECU.
LQ9 with truck Norris cam, TBSS intake, 92mm throttle body, 4” cold air intak.
I’m still working on trying to get a good base tune set up.

[blindsquirrel]

If you got what's in that tune file from this sheet you did it wrong:
GM Gen4 injectors converted to Gen3 format for P01-P59 PCMs.xls

It has tables for both returnless and referenced/return, for both Flow Rate & Offset (those are the only ones that are different depending on the fuel system type). Make sure to look at it long enough to understand what everything is. Nine different injectors in there, pick the right page for your number from the tabs at the bottom.

[RDF1]

ACDelco 12613412 50LB injectors.
91 octane
vacuum reference return style system
regulated to 58psi.
I pulled the injector data from a forum post for that injector part number.

It?s an LS swap in a 1979 Firebird. Stand alone harness with a factory ECU.
LQ9 with truck Norris cam, TBSS intake, 92mm throttle body, 4? cold air intak.
I?m still working on trying to get a good base tune set up.

Have you checked for vacuum leaks and such?

Here is the correct data.

[Travis7109]

Have you checked for vacuum leaks and such?

Here is the correct data.

You're awesome! I'll make that change in the morning and go from there. Thanks!

[RDF1]

need to add throttle follower and IAC Position to the datalog to see if thats commanding it to hold the rpms up.