high REVs on cold crank

[2001CamaroGuy]

04 Silverado, 5.3Liter, A4

On "cold" cranking (coolant is less than 130 degrees), the engine cranks but immediately goes to anywhere between 2500 and 3000RPM. It hangs there for about 1-3 seconds before falling the the desired idle speed. Above about 130 degrees, I do not have this much of a problem (revs to only about 2000RPM, hangs for the 1-3 seconds, then falls).

What I have noticed is with the key on but the engine not running, the throttle is sitting at 16% (electronic throttle). When I start the engine, the throttle remains at this setting (16%) for the 1-3 seconds. It then drops down to anywhere between 5-10% (the required throttle setting to idle depending on coolant temps).

WHY is this happening? What dictates the cranking throttle setting? Attached is the current file.

[2001CamaroGuy]

SOMEONE must understand this stupid electronic throttle system!

WHY does the computer command the throttle to rest at 16%? Why not 0%?

[WS6FirebirdTA00]

because with 0% throttle the truck won't run. Post a scan. What are the mods?

You also need to be more patient and allow for more than just a few hours before looking for a response and posting back up...

[2001CamaroGuy]

I'll have to scan it tomorrow. What I'm trying to figure out is what exactly SETS the throttle base setting. I reduced both the Friction and Startup Airflow Initial settings (at one point zeroed them out entirely at one point). This prevented much of the high cranking RPM but I'm still getting a 16% base setting (which I just don't understand).

[WS6FirebirdTA00]

You will have a high startup TPS%. Idle airflow will also set the TPS%. 16% is high but most warm idles are around 7-8% or so, so it is not THAT high.

[12secSS]

I can’t look at your file from work, but based on what you are saying these are the areas you need to address which commonly cause high rpms at start up. You need to look at the RAF table, if it is set to high it can cause the TPS to allow more then needed airflow into the engine, then it settles back once idle routines are activated. Also, look at your Startup Flare Control, this is a timing table that reduces spark advance to help control high idle situations on start up. Just some ideas.

[EC_Tune]

The idle params are messed up.
Check this stock file as a go-by.