2004 DBW - cranking and idle throttle limited?

[kjlindgr]

Hey guys,

I have a 2004 Corvette LS1 here with a fairly aggressive TSP cam in it. It's been an absolute bear to dial the idle in, but I think I have it sorted with the engine hot. The issue I'm running into now is when the engine is cold. The DBW throttle doesn't open any farther than 17.3% while cranking or while at idle, no matter how much additional air flow I command, or how much additional airflow the STIT tries to throw at it. I have a log for reference. You can see it's barely able to maintain an idle even at this 17.3%. This limit isn't an issue when hot, but when cold it definitely needs more throttle.

Can anyone tell me if this limit is something that can be overcome? I'm just not able to find a way to get it to raise no matter how much idle air I give it, startup air, or friction airflow.

Under Airflow->Electronic Throttle, I do see that there are some max idle area and position values, but they also come with a warning about bricking the TAC. Of course this is not something I want to do so I did not mess with these.

cold_crank.hpl

[kjlindgr]

I didn't get any responses and had to move forward with the project. I didn't want to risk bricking the ECU by adjusting the idle throttle opening parameters so I plumbed a small vacuum line from the intake, post MAF, to the EVAP port on the side of the intake bypassing the throttle body. I didn't have enough commitment to drill a hole in the throttle blade, but this effectively accomplishes the same thing. Works great now giving the engine just enough air when it's cold, and I still have idle control when it's hot.