2009 Silverado Truck Norris Start with Hanging Throttle

[J_S_R]

2009 Silverado LTZ, Truck Norris NSR, stock exhaust
Wideband is not installed yet

I followed Matt Stanfords video on Idle Startup Tune here as he gave specifics from his experience with the Truck Norris
https://www.youtube.com/watch?v=1QIRgaGfzWk

It starts and idles ok but I'm experiencing a couple of things that I need to get resolved before I feel comfortable driving it to get the wide band bung welded in. Once it gets warm, Stabilitrak warnings are set and the throttle hangs. Sometimes the throttle is just very slow on the return and sometimes it sticks at 2-3K RPM and holds.

I've uploaded my stock tune (with DOD turned off), the current idle tune, and a log of the slow throttle. On the log, I couldn't get it to stick but you can certainly see the slow throttle return. Any advice is welcome as this is the first time I've worked on a LS with anything bigger than a Stage 1.

2009 Silverado LTZ - Stock DOD Delete.hpt
2009 Silverado LTZ - DOD Delete - Truck Norris 20240511 - Start.hpt
20240513 Throttle Slow.hpl

[edcmat-l1]

BRAF is way too high for that cam.

[J_S_R]

BRAF is way too high for that cam.

Do you have a suggestion for what is a more appropriate?

[blindsquirrel]

https://forum.hptuners.com/showthrea...e-tuning-guide

[04silverado6.0]

See if this helps you out any.

[J_S_R]

See if this helps you out any.

I didn't have a chance to go through the tuning guide yesterday but I did try this tune this morning, Similar to the first the initial crank was VERY long but then it started and appeared to idle fine again. But, on throttle blips it was SLOW to return, then on the last blip it climbed and hung. I had to shut off the ignition.

20240514 Throttle Hang.hpl

[edcmat-l1]

Put your BRAF ETC multiplier and your throttle follower back to stock. Data log and report back.

[Alvin]

Put your BRAF ETC multiplier and your throttle follower back to stock. Data log and report back.

Yes.. do this or somewhere in between is likely where it will end up.. maybe compare the differences and multiply the DIFFERENCE by .5

[J_S_R]

Put your BRAF ETC multiplier and your throttle follower back to stock. Data log and report back.

This seemed to help. I only had a minute to try it this morning and it atleast made it better when cold.

[edcmat-l1]

Now it looks pretty normal.

[04silverado6.0]

You can try that throttle follower table and see how you like it. It only makes it less aggressive in gear. Wonder why the BRAF multiplier is so low on that os?

[J_S_R]

I didn?t get a chance to try this tonight but I will. I did try another cold start and the first start cranks for several seconds before it starts. After the initial start, the subsequent starts are quick. Is this likely a temperature/timing issue?

[04silverado6.0]

After the maf and ve are dialed in i would think it should crank better. Im not sure what ect you are having long crank at but i made some adjustments at cooler temps. See if this is better or worse.

[edcmat-l1]

You can try that throttle follower table and see how you like it. It only makes it less aggressive in gear. Wonder why the BRAF multiplier is so low on that os?

Alot of them have that same multiplier.

[edcmat-l1]

I didn?t get a chance to try this tonight but I will. I did try another cold start and the first start cranks for several seconds before it starts. After the initial start, the subsequent starts are quick. Is this likely a temperature/timing issue?

Could be too much fuel or not enough airflow or a combination of both. First thing to do is check the fuel pressure. Unless you know what it is you don't know if you're "tuning around" a mechanical problem or not. The fuel could be draining back.

[04silverado6.0]

I also thought of fuel pressure issues. I think that would be a good idea to check pressure on the cold pump. I say dial in the fueling completely before any further tuning to correct any issues. Cant correct a bad airflow model with bandaids.

[J_S_R]

Fuel is a at 60psi cold. The latest file seemed to
make it better.