How to deal with warm start after heat soak?

[abc]

I have looked around some and haven't noticed any heat vs. time tables on my 2000 LS1, TEA heads, stock intake, ID 1050X injectors, centrifugal blower, 236/249 .610 115 LSA cam, 4" stroke.

Have you guys come up with a way to deal with the excessively lean starts and drivability after the engine has been up to operating temp. then shut off for the time span between 20 min. to an hour or so? I was looking at some Gen 4 stuff and noticed they have a few more options then the Gen 3 stuff to deal with this type of issue. I am currently running in open loop and for reasons like this I want to attempt to go back to closed loop but I also have a question about that also.

Does the Gen 3 Ecm in regard to the nb02's make adjustment decisions based off of AFR or Lambda? Now that I am tuning based off of Lambda it has me thinking that the ECM-2300 variable needs to be changed to Stoich. for E10 as back in 2000 E10 was not as prevalent? I'm getting ready to start testing with the nbo2's in attempt to put it back in CL to at least use the STFT's and it appears all the nbo2's switching is based of off an AFR of 14.63:1? Assuming my wbo2 is correct, in my logs right now before I changed the switching voltage of the nbo2's, they would switch well around 1.03 lambda, which tells me they are switching for stoich of 100% gasoline? Based on the description in ECM-2300, if I change the Stoich. value to 14.2:1, the nbo2's will now switch at 1 lambda for E10? Is this how it is normally done? Can you also tell me what else in the background changes when we change the ECM-2300 variable?

I included a log of a heat soak start with idle at the beginning and idle at the end and you will notice the difference after the engine temp. and supporting systems have normalized. I believe it has a lot to do with fuel temp. and the temp. of everything that delivers the fuel but I don't know if there is a way to compensate for it? I also included a tune file just for reference as it is not the current file, but it does at least show the operating system and related tables. The current tune file is in OL without using the STFT also.

24-05-19 20-24-25.hpl
2000 vette force motor change 23.hpt

[Alvin]

Is there an obvious difference in how the car is running on this lean restart?

While the engine is hot in how we think a engine is hot.. it isn't like running hot on those restarts. Only the fuel that gets vaporized gets burned and the rest goes through the tail pipe. Also the wideband will have error as a function of pressure and temp.. so the wideband could be reading off. What I'm getting at is what you are observing is fairly normal as long as it doesn't have any driveablity complaints to accompany this.

This is a common complaint and IMHO people don't have a problem really.. they are just looking for a number in the scanner.

[abc]

Alvin, Thanks for the response and you are correct in your assumption, if I didn't have the data to look at I wouldn't know the AFR was showing skewed during those heat soaked scenarios. As of now I'm not experiencing any ill side effects from what appears in the data as an abnormally lean situation. Thanks for the confirmation that this is a normal scenario.

My idle quality is not where I want it to be as of right now, that's one of the reasons I was questioning the lean heat soak issue, but I will continue to work on my idle issues. Do you think the idle adaptive tables help a significant amount trying to get a more steady idle with this many aftermarket parts or will I just be pissing in the wind trying to settle it down using the idle PID tables? Right now it does have the common newbie tuning issue of the idle dips periodically 100 to 200 rpm below the set point and may bounce 100 to 200 rpm above the desired set point. Those numbers are on the extreme side, usually the dips and bounces are less than 100 rpm.

Any input on the ECM-2300 table?

[Alvin]

If I do 100 cars I might touch idle airflow pids on 1. Most people who go into that are masking other problems.

Fueling, the fueling as the engine decelerates, and timing are key for a good idle. Everything sorta falls inline automatically when those fundamentals are done.

Not sure what you mean by ecm 2300.. the stoich setting? That's what it shows for me. You can set it up to 14.1 if you know your going to be at roughly E10.. or leave it alone. Its only a 4% difference anyway.

[SiriusC1024]

Where is the IAT installed?

[SkinnyG]

I tried all kinds of stuff trying to fix the "hot restart lean" issue on my Speed Density (scaled tune for 2-bar) turbo LQ4 (IAT in piping just before TB), and I finally had success by changing the Cylinder Charge Tmeperature Bias vs. Airflow settings at 0, 10, 20, and 30g/s to "1.000" and scaling everything else all the way up to the unchanged 150g/s column.

I tried all manner of things, but this is what worked - no hot restart lean issues since!

[abc]

The IATS is in the charge pipe about 8 inches before the throttle body.

Skinny, any ideas why your solution worked? Seems to me part of that solution is counter intuitive unless the fueling based on IAT is working to your benefit?

[SiriusC1024]

That's the airflow>general>complex temperature model. It's something you adjust based on IAT position. 1.0 disables bias. 0.0 biases toward IAT. 2.0 toward ECT. Hover your mouse over the complex temp enable box for the solution in the description that'll read out at the bottom.

[SiriusC1024]

In addition to the complex temp settings, there's always this option. Bosch IAT and MAP combo (TMAP).
https://www.bmotorsports.com/shop/pr...oducts_id/1721

Specs for IAT and MAP calibration included in the specs tab. Wiring components in the associated parts tab (TMAPs at other ranges there, too).