Throttle Decay

[gmtech16450yz]

Yes, Throttle Body, along with the rest of the engine internals are all stock. Only modifications are Headers, CAI, and no emissions equipment.

I have made all the changes you suggested. I will close & reopen the scanner and open each of the three LS3 files you had sent, and go do another log.

Should I be changing the idle airflow now to compliment the added timing?

Exactly! See, you got this! Remember that idle control is a delicate balance of ignition timing and airflow (assuming fueling is ok). Your ignition timing was super low because it was trying to take away ignition timing because it had too much airflow. Again, that's a good example of why increasing the authority of the error tables isn't the best approach. Sure, you could have the adaptive timing take away MORE of the ignition timing if the rpm's were too high, but then you end up with even less timing and a cr@ppy running engine. The goal is to keep enough ignition timing and airflow so that they're in the centers of the error table's range of control. I like to also keep ign timing as high as possible while still giving it enough range to increase it in case the idle goes too low. Ideal (IMHO) for most LS engines is ROUGHLY 20-25 degrees idle timing. No less, preferably more.

[NJ_Phil]

John.
This makes a lot of sense and I'll be giving it a try tomorrow. I was dumb enough to only change Idle airflow for the RPM I was idling at and only for Neutral. No wonder why it didn't follow down and occasionally stalled when it couldn't figure out what gear I was in. As for the noodle thing....got you on that but why would anyone want it to not follow as fast as possible? I would thing the faster response the better

[gmtech16450yz]

John.
This makes a lot of sense and I'll be giving it a try tomorrow. I was dumb enough to only change Idle airflow for the RPM I was idling at and only for Neutral. No wonder why it didn't follow down and occasionally stalled when it couldn't figure out what gear I was in. As for the noodle thing....got you on that but why would anyone want it to not follow as fast as possible? I would thing the faster response the better

That's the beauty of electric throttles, that you can make the response fast or slow. Here's a situation that comes to mind, 2nd gear, wound up tight almost at redline and you're on a curvy road coming on and off the throttle in a high hp car. Having a really fast reacting throttle or one that goes quickly straight down to "zero" would be scary. That's how you break axles and other hardware. So being able to smooth out that off/on transition makes it easier on the hardware and things like maintaining traction.

And yeah, make those gear choice tables all the same for now. You can always play with them later, but it will make your life much easier if you eliminate the possibility that the ECM will be using the wrong gear table values.

And also yeah, the rpm rows that are in tables like the min idle air are what the rpm's are at WHEN you change throttle positions. So if the throttle is hanging when letting off at 4k rpm, you have to lower everything from the 4k row and below. (Or at least lower the values at 4k but not down BELOW what the lower values are. They need to ramp smoothly.) Lowering the values in the 600 row won't do a thing for when you let off the pedal at 4k rpm. That goes for the throttle follower tables too.

[NJ_Phil]

I definatley want different follower values depending on which gear I'm in then...

So see if I have this straight:

At 3000RMP, Airflow comes from the main VE table or MAF, fuels accordingly, yada, yada, yada
Returning the pedal to 0 will "request" airflow as per the Idle airflow table for that RPM. Applied spark then comes from the coastdown table.???
The torque setting in the follower controls how agressive the throttle closes in order to reach the airflow in the Idle table.

Assuming that's correct. What is the "Airflow Step up" and "Airflow Step down" tables for. These are based on pedal position.

[GHuggins]

Unless I'm wrong - multipliers based on pedal position in relation to the throttle follower tq table... I usually only adjust the upper cells...

[69halfton]

I did some playing around with the tune based on the thread here. with all of the changes gmtech had asked me to do, I had a hunting Idle & rich condition at Idle (I assume because I hadn't fine-tuned idle airflow).

So, I put the timing back to the way I originally had it tuned, and just focused on air flow.

Like suggested, I re-enabled throttle follower airflow by putting the max back to stock.

I then strengthened the throttle follower torque above 2000 rpm, and lowered the base idle airflow above 2000 rpm.

I now have instant throttle blade movement down to just 3% (Idles around 9%) for a much nicer, and much quicker shift.

However,I'm still flying blind on the logs. I have re-opened, re-loaded and tried every combination of opening layout/chart/channel I can think of, but can't get the airflow PIDs to populate. any advice here?

[NJ_Phil]

There are a lot of channels open and sometimes the scanner will drop some. Try deleting the ones you don't need, like fan speed, fuel pressure, oil pressure....some are those are set to the fastest polling time (0 ms)

[GHuggins]

The pids may not even be available for your vehicle - go through the list after repolling and see if you can find them by hand for your vehicle...

[07GTS]

However,I'm still flying blind on the logs. I have re-opened, re-loaded and tried every combination of opening layout/chart/channel I can think of, but can't get the airflow PIDs to populate. any advice here?

yea i dont have those idle airflow pids in mine either, only one i have is "idle desired rpm", if u put yours in and u dont get the blue arrows then they are not there to log

[NJ_Phil]

yea i dont have those idle airflow pids in mine either, only one i have is "idle desired rpm", if u put yours in and u dont get the blue arrows then they are not there to log

Same here... They show up in the channel list with the blue arrows but disappear when I start the scanner. Would have been pretty cool to see the airflows though.

[gmtech16450yz]

Damn, sorry about that! I didn't think about those PID's not being supported in your particular OS's.

It sounds like you're figuring it out though Jason even if you do have to "fly blind". So you already learned how to get the throttle to go from 19% to 3% in between shifts. If you look at the values you had in your min air table that made it go down to 19%, and then what the values are that got it to 3%, you'll have an idea on what the final numbers need to be. For instance, if you have the same value in the 2000rpm column that resulted in the 3% throttle value, you know that's too low for idle. (That's actually lower than I would like for decel and in between shifts. Shifts are smoothest when the rpm's drop fast, but not TOO fast.)

So in other words, if your min air table has the same values in it from whatever rpm it's dropping to 3%, all the way down to 400-600rpm, that's too low. That means your adaptive idle is having to bring it back up from a minimum of 3% to the 9% it actually needs for a stable idle. Get the minimum air rate table values so that it's closer to 9% all on it's own, without the adaptive error tables doing much. Make sense?

[69halfton]

Yes, that makes sense.

I'm still doing some playing around with it, but Since altering the Minimum airflow tables, I have a lean condition on Coastdown. I am having a horrible time getting the scanner to log any decent information- I can't even get it to log injector pulse width??

as soon as I lift off the throttle, my wideband goes off the charts lean, almost like DFCO is enabled (Its not). I found a back-door way to fix it by bringing my minimum injector pulse width up slightly- which proved to me that too much fuel is being pulled out on decel- but I'd like to fix it properly.

Where can I adjust for this? It seems strange to me that by me taking air away I now have a Lean condition??

[7SECONDS]

I am following this thread closely. Since I installed my Mantic twin disc clutch kit which is equipped with a lighter flywheel. The off idle driveability is horrible. Engine rpm quickly goes down making the car die when engaging and disengaging the clutch in a parking lot. All due to the lightened flywheel I am sure. I need to make the same adjustments in throttle decay rate.