I have the Holley HP EFI kit for LS1. This is on an 03' LQ4 with a cam and heads done. I am also using a cable driven tb off an 04' van with a factory 01' truck throttle cable.
Turn the key and engine fires great cold.
Once warmed up I could not get it restarted...
I had to turn the IAC way up from the baseline LS1 tune
With the IAC under 78%, the engine would not start.
The directions to the kit say the IAC should be between 5 and 15% when warmed up. The IAC will not go under 70% when warmed up. It says I should adjust the throttle open, but how do I do that? It is a factory van tb and throttle cable. Is this important or necessary to proceed? I checked the cable and it allows the butterfly to fully close and open so is working properly.
The only variable I see is the van tb has a small hole drilled (1/16") in the bottom section of the tb which looks factory drilled. My previous truck dbw throttle body does not have this.
Engine idles great and I have a total of about 30 minutes idling on it. I can slowly ramp up the throttle (when parked of course) to various RPM’s. Whenever I lower the RPM, no matter how gently, it will die when it reaches around idle speed. I am not sure what is causing this or if it is related to my issues above.
Like stated above, because of the larger cam and heads it needs more air to idle. It is idling fine cold becuase of the denser air but once it is hot it requires more. There should be a small throttle stop screw on the side of the throttle body or drill the hole larger. The tune is a base tune for a stock ls motor so it will require adjustment for your upgrades.
By the way good choice on the Holley efi, a friend of mine just got it for his car and it is awesome.
Thanks for the help, I hope to find a screw. Sounds like a one solution fix all deal.
Aside from this, which is probably due to me being new to efi, the Holley kit is great. A few things specific to this kit of the LS could be more specifically laid out in the directions. Otherwise, turn the key and the engine immediatley fired from the base LS tune.
I have been taking notes and plan to post up about the full swap once I am done.