2006 Tahoe Cammed Start Up Issue

[HKrue94]

2006 Tahoe with a BTR Stage 2 NSR cam that I am trying to get the BRAF dialed in. From Start Up (81 degrees) to about 130 degrees, I'm having a hard time figuring out what is wrong. Cold start is 81 degrees cause I'm in Texas. Things that seem out of place:

- Spark Timing
- O2B1S1 & 02B2S1
- Desired RPM (commanding 905 but shows 1175)
- STIT

I logged the desired idle air against the ECT and from 90-degree column to the 111 column, and the airflow is very high when compared to the rest of the ECT columns. Does this seem normal? Any info and help is greatly appreciated. Log File and Tune posted below.

Start UP - V1.hpl2006 Tahoe Cam VE tune + Gear Ratio Adjust V2.hpt

[abc]

Are you sure this is the tune file you used for this log? As you noticed the desired rpm and actual rpm don't match, yet the ECM is pulling the timing down to almost zero. I'm new at this also and my first swing would be to lower the base idle airflow in your trouble area and see if the ECM starts putting the timing back in.
I'm sure one the experienced guys will chime in with more insight.

[Alvin]

What is the issue exactly?

To me it looks like it can use more VE tuning. You'll be chasing idle issues while that isn't correct.

[edcmat-l1]

It's catalyst warm up. Right in that same ECT range it peaks then falls off. Because it pulls the timing so low the throttle blade has to react to maintain idle speed. That's why your idle trims go positive and it looks like there should be a hump in the BRAF table. Perfectly normal.

Did not look at the rest of the tune file.


catalyst warm up.jpg

[HKrue94]

The issue I'm pointing towards is the pulling of timing down to around 0 degrees after startup and my desired RPM not matching my tune. Other issue would be the high amount air needed right after start up. Is the VE table contributing to these issues?

[HKrue94]

It's catalyst warm up. Right in that same ECT range it peaks then falls off. Because it pulls the timing so low the throttle blade has to react to maintain idle speed. That's why your idle trims go positive and it looks like there should be a hump in the BRAF table. Perfectly normal.

Did not look at the rest of the tune file.


catalyst warm up.jpg

Can I zero this out to help dial in BRAF

[codykeen0923]

The issue I'm pointing towards is the pulling of timing down to around 0 degrees after startup and my desired RPM not matching my tune. Other issue would be the high amount air needed right after start up. Is the VE table contributing to these issues?

Without a log its hard to tell . Dont mess with anything under idle except your base airflow and your throttle follower and cracker to help with idle drops. Log short term idle trim and see how much base running airflow needs to be added or subtracted. If the fueling isnt 100% correct nothing else is gonna be right.