Gen4 idle tuning guide

[BigMike42]

Now Mike, when you say to (0) these out, your referring to "all" the rpm follower tables and just the air max torque follower table - correct? I assume you don't leave them like this when your done either - right?
Thanks

Honestly, I don't know. I just nuked every single follower table (rpm tab and airflow tab) and did a quick log and noted that the TPS and ETC% did not move. I am sure we can narrow down which table to exactly zero out.

You are correct, I turn everything back on once base airflow is found. This is just to isolate the base airflow table. I know how to fine tune integral, but I have no idea how to fine tune the follower table yet. I know the torque table has negative values for less airflow and positive for more, but I am not sure what all the other tables do (like the step tables).

I think a good sanity test would be to max out the torque table to see if it even helps. The rpm should hang if it's actually doing much.

[GHuggins]

I use the actual torque table to try and get more idle torque on "some" applications where I might still have idle dip issues or something like that going on... The step tables control how fast the throttle will open or close - never tried going "much" past what's there, but I have modified the step down table to get the throttle to close quicker...

I still haven't had a chance to try all of this out, but your the only one who's covered them in the depth that you have

[BigMike42]

I think you'll like it . It's nice changing base airflow and seeing concrete changes right in the scanner, so you know exactly what the change was.

I gotta mess with the follower a bit. Right now to keep my car from dying, I hacked in some extra idle air in the 1200+ cells, but what happens is sometimes my car drives itself if I hit that exact RPM and let off the gas. It "works" but definitely not optimal. And even basically zeroing out coast integral doesn't solve the RPM drop coming to a stop in some cases, so this is where the torque follower tables must come into play. There are so many moving targets.

[BigMike42]

Updated guide with step to remove follower values

[Niemer]

I tried your method before you posted about the follower tables and got crazy idle swings, it just wouldn't settle out. I'll try it again soon with zeroing those tables out and report back.

I got my idle pretty well dialed in using GHuggins method, but would like to see if I can get it to +/-20 rpm vs the 35-40 I have now.

[BigMike42]

I tried your method before you posted about the follower tables and got crazy idle swings, it just wouldn't settle out. I'll try it again soon with zeroing those tables out and report back.

I got my idle pretty well dialed in using GHuggins method, but would like to see if I can get it to +/-20 rpm vs the 35-40 I have now.

Ok let me know. Tps and etc should be locked. If not, something else is trimming it.

[BigMike42]

Played with throttle follower torque. I shifted the values up about 37 ft/lbs. So 3000 rpm is 0, tapering to positive numbers all the way down. And above 3000 is slightly negative. It definitely slowed my RPM drop. I don't know when integral comes into play vs this table, but it seems like the follower torque is immediately when lifting the throttle (kind of like proportional airflow).

[BigMike42]

Updated guide. Ac has to be off. Got weird results with it on. Couldnt get idle to stabilize.

[waynehartwig]

Why disable proportional idle vs fix it?

[gmorris]

Why disable proportional idle vs fix it?

Whatever works for your car. Mine needs prop in order to stay smooth over time. I use the 2013 corvette A6 table and find it works beautifully. Without prop enabled mine idles well for about 10 seconds then starts to surge a bit.

[waynehartwig]

Whatever works for your car. Mine needs prop in order to stay smooth over time. I use the 2013 corvette A6 table and find it works beautifully. Without prop enabled mine idles well for about 10 seconds then starts to surge a bit.

You kind of confirmed my question, but didn't give an answer.

I'll reword my question... Why disable proportional idle vs adjusting it to work correctly

[gmorris]

You kind of confirmed my question, but didn't give an answer.

I'll reword my question... Why disable proportional idle vs adjusting it to work correctly

I guess my point was that not everyone does disable it....

Maybe Mike will chime in on his explanation.

[BigMike42]

Proportional idle barely even comes into play during idle on a stock tune with a stock car. Most stock tunes have it at 50+ rpm. No stock cam is oscillating 50 rpm, so it's only used as an instant correction as a fail safe. Integral is much more critical, hence why most cars have it set at about 12 rpm to start correcting.

I want the least amount of airflow correction as possible in a cammed car, otherwise it's harder to keep things under control. Once you find the right base airflow, spark does most of the work within the normal oscillation of the cam while integral makes very small corrections (.4% TPS in either direction).

When I leave proportional on, I get bad surging if the RPMs start dipping more than 50. If you leave it on, I recommend pushing out to 75 or even 100 rpm.

Edit, I suppose on a stick car you can leverage it so the RPMS drop quicker between shifts, so keeping it on makes sense in that case. I'd still push the RPM out though so it doesn't come into play during normal idle.

[BigMike42]

Whatever works for your car. Mine needs prop in order to stay smooth over time. I use the 2013 corvette A6 table and find it works beautifully. Without prop enabled mine idles well for about 10 seconds then starts to surge a bit.

I like the coastdown integral for this file. Use them for both normal/coastdown with great results. Technically integral is based off proportional in the PI equation (I believe it's a simple multiplier since lowering them lowers airflow), so I copy the prop values over as well. Raising the RPM enable simply removes the proportional from actually getting added or subtracted. I would imagine zeroing out the table will render integral useless, but I haven't personally tested it.

[waynehartwig]

Proportional idle barely even comes into play during idle on a stock tune with a stock car. Most stock tunes have it at 50+ rpm. No stock cam is oscillating 50 rpm, so it's only used as an instant correction as a fail safe. Integral is much more critical, hence why most cars have it set at about 12 rpm to start correcting.

I want the least amount of airflow correction as possible in a cammed car, otherwise it's harder to keep things under control. Once you find the right base airflow, spark does most of the work within the normal oscillation of the cam while integral makes very small corrections (.4% TPS in either direction).

When I leave proportional on, I get bad surging if the RPMs start dipping more than 50. If you leave it on, I recommend pushing out to 75 or even 100 rpm.

Edit, I suppose on a stick car you can leverage it so the RPMS drop quicker between shifts, so keeping it on makes sense in that case. I'd still push the RPM out though so it doesn't come into play during normal idle.

There is more to proportional and integral idle than that... But you're right, at 50 (if it's set at 50), will cause problems if the rest of it's not right.

[schpenxel]

Big thanks to this thread. Finally got a chance to read it all. Makes a lot of sense now.

Also, apologies to any and everyone I told to "just adjust the min airflow", lol

[kennyspec]

awesome thread. My cammed car (229/236) idles very well and is very stable, but when blipping the throttle sometimes the idle will dip below target (850rpm) by maybe 200rpm and then come back up. is it the integral table that controls the dips when the idle is overshot and goes too low?

[waynehartwig]

awesome thread. My cammed car (229/236) idles very well and is very stable, but when blipping the throttle sometimes the idle will dip below target (850rpm) by maybe 200rpm and then come back up. is it the integral table that controls the dips when the idle is overshot and goes too low?

That's probably throttle follower air...

[reubone]

zero'd out all the tables mentioned in this thread but tps and idle will still fluctuate around commanded idle speed regardless of how low i set the base running airflow table. only when i blip the throttle does it snap to my commanded airflow. there is an idle control table that i do not have access to to keep it from interfering

[reubone]

just answered my own question. set max allowed idle to 200 rpm and mystery idle control went away. still testing