e38 idle and off idle is kicking my a**

[madkidd007]

edit: be sure to read post two as i have an update


first ill give the issue, then the details or the setup, and last ill be smart and post my last log and tune file to skip being told to post it up.

As i depress the throttle slowly the motor will drop in RPM in park, in gear it will stall. If i dont baby it and push it quicker but still on the conservative side it will rev just fine so its ONLY a light throttle stall/stumble when going from 0% to say 5% accelerator pedal position. I was having the issue in park also but managed to eliminate it by increasing the airflow minimum table. Still has a slight surge when coming back to idle but not bad enought to push through the converter. I have referenced LS7 and the GM crate 525 LS3 tables and I'm well above them both now. Startup I have dialed and it lights off immediately.

If it was a Gen3 setup id be good i believe, this is my first Gen4 with a cam swap so I'm still learning the specific tables and getting frustrated

Software/electrical
E38(2007)
2 Bar OS strictly to get lower fan temperature settings
LS3 Map sensor
LS3/LS7 MAF
corvette Throttle Pedal
LS2 throttle body from 2007 Vette
O2 sensors 4" after exhaust manfiolds


Mechanical
LY6 6.0 stock shortblock and heads
cam specs 225/236 at 50 thou 110 lobe 525/525 on lift
LS2 intake manifold
12569113 LS2 injectors from 2007 Vette
2006 GTO fuel tank/pump non return fuel system
TR5 plugs gapped at .045 if i remember correctly
160* thermostat
4" air intake piping

ASA SURGING RETURNING TO IDLE IN GEAR.hpl
lincoln ASA tune 2 bar OS with 525 CRATE SETTINGs.hpt

[madkidd007]

So after posting last night it was bothering me and came back this morning to look a little deeper. Lucky me someone else posted and issue with n LS3 with a similar issue so after looking at his table i seen his stock airflow was wildly different than mine and did some math to get close based off of engine volume. Guess what it is no longer stalling on tip in, so apparently my thought that i never shared was right, too much air and thats why a quicker throttle apply would work as it was getting past the bad mixture point.
It did make the surging issue worse when coming back to idle in gear and when you let off from loading up the converter it damn near stalls before starting the surging which lasts for about 8 seconds

With all that said can someone please help explain how to properly calibrate my base airflow table?

here are the new log and the new table settings. yes they are the same file name as above since i dont even want that old tune in my references anymore

ASA SURGING RETURNING TO IDLE IN GEAR.hpl
lincoln ASA tune 2 bar OS with 525 CRATE SETTINGs.hpt

[Turbo6TA]

This may help somewhat with your Base Running Idle Airflow problem ..

_______________________________

[Leva]

What tunning manual is that page from?

[Turbo6TA]

Not from a tuning manual ... It's something I found on the internet, but I re-wrote it and amended it a little.

The chart was copied from my tune file after making the changes (2011 Corvette LS3 with 220* / 234* . .585" / .585" . 118* LSA cam)

[Leva]

I see. Good write-up. Was hoping there was a complete tuning guide like that. Would make life alot easier then sifting through these forums for random tid bits of info.

[Turbo6TA]

You got that right !

[madkidd007]

This may help somewhat with your Base Running Idle Airflow problem ..

_______________________________

i appreciate that, the timing thing ill try this weekend and see if i can get it dialed. Ironically i got the startup airflow down way before I got the base airflow close, it fires right off just slightly higher than my desired idle same as a factory car does. The issue I have with starting from a base is when the 5.3 spun a bearing I replaced it with a 6.0 and swapped the cam all at the same time, therefore everything is so different refencing a good running previous tune is a no go. I am confident the rest is pretty close, cept for the final VE which ive been closing in on since i daily this car. Just wish there was a histogram formula we could use to watch the airflow but hey its a custom vehicle so it is what it is.

thanks,
Josh

[hjtrbo]

The quick version. Should take you about 20 minutes to have it pretty good once you've had some practice.

Prerequisite: Idle fuel good and engine nice and warm.

Set base timing to 17-19deg.

Use the VCM controls to command 800, 1000, 1200 rpm idle for 30 seconds at a time. Note down the average steady state dynamic airflow. Do the same with your right foot for 1600rpm if the scanner won't let you go that high. Enter these values in the respective columns of your min air flow table. Just make gear and PN the same for now. Blend out from 1600 upwards kinda following the OEM shape raising cells where required.

Cut proportional in half and take 0.8 off integral.

Move idle adaptive spark over 1 column over to the right at a time.

Note down average steady state torque at your desired idle speed. Lower airmass A in the respective and lower rpm cells then blend up to 1600rpm. Keep lowering until average torque reports around 10-20Nm. OR, as a quick fix you can use RPM A instead as its quicker. If your average torque is say 75Nm then for those columns around idle in RPM A you would subtract (if number is negative, then make more negative) 75Nm value recorded from scanner - 20Nm desired torque = 55Nm to be subtracted from RPM A idle cells.

[Alvin]

So after posting last night it was bothering me and came back this morning to look a little deeper. Lucky me someone else posted and issue with n LS3 with a similar issue so after looking at his table i seen his stock airflow was wildly different than mine and did some math to get close based off of engine volume. Guess what it is no longer stalling on tip in, so apparently my thought that i never shared was right, too much air and thats why a quicker throttle apply would work as it was getting past the bad mixture point.
It did make the surging issue worse when coming back to idle in gear and when you let off from loading up the converter it damn near stalls before starting the surging which lasts for about 8 seconds

With all that said can someone please help explain how to properly calibrate my base airflow table?

here are the new log and the new table settings. yes they are the same file name as above since i dont even want that old tune in my references anymore

ASA SURGING RETURNING TO IDLE IN GEAR.hpl
lincoln ASA tune 2 bar OS with 525 CRATE SETTINGs.hpt

Looking at your log.. its a bit limited but I can tell looking at the stock O2s that the car is rich at an idle. You might be able to get the car to idle messing with idle airflow, base airflow, etc but you need to fix the fueling first. Fueling is 100% the most important part in getting the idle correct.

That cam idles pretty dirty. I'd strongly suggest running this in speed density for more accurate fueling.

[madkidd007]

The quick version. Should take you about 20 minutes to have it pretty good once you've had some practice.

Prerequisite: Idle fuel good and engine nice and warm.

Set base timing to 17-19deg.

Use the VCM controls to command 800, 1000, 1200 rpm idle for 30 seconds at a time. Note down the average steady state dynamic airflow. Do the same with your right foot for 1600rpm if the scanner won't let you go that high. Enter these values in the respective columns of your min air flow table. Just make gear and PN the same for now. Blend out from 1600 upwards kinda following the OEM shape raising cells where required.

Cut proportional in half and take 0.8 off integral.

Move idle adaptive spark over 1 column over to the right at a time.

Note down average steady state torque at your desired idle speed. Lower airmass A in the respective and lower rpm cells then blend up to 1600rpm. Keep lowering until average torque reports around 10-20Nm. OR, as a quick fix you can use RPM A instead as its quicker. If your average torque is say 75Nm then for those columns around idle in RPM A you would subtract (if number is negative, then make more negative) 75Nm value recorded from scanner - 20Nm desired torque = 55Nm to be subtracted from RPM A idle cells.

ok that just confused the hell out of me, i appreciate the effort to help but just tellng me to cut something in half, move adaptive spark over, etc doesnt help me or anyone in the future seeing this to understand why and the effect. Im very much the type that does just do something without understanding

[madkidd007]

Looking at your log.. its a bit limited but I can tell looking at the stock O2s that the car is rich at an idle. You might be able to get the car to idle messing with idle airflow, base airflow, etc but you need to fix the fueling first. Fueling is 100% the most important part in getting the idle correct.

That cam idles pretty dirty. I'd strongly suggest running this in speed density for more accurate fueling.

yea the car doesnt like fuel mixtures down low with this much cam duration and the file youre looking at was a quick test that i saved to give the thread something to reference. I have the car idling just fine in neutral and even in gear, just trying to eliminate the surge effect i get for a few seconds. I will be keeping MAF and have zero desire to run speed density. You can not smell it idling so fueling is pretty close. My main goal is trying to dial in the airflow table as the rest i can get ironed out and it drives great

[hjtrbo]

Ok, been there done with the idle tuning guides on this forum. They take way to long to go through and so much back and forward with flashing each step. Then after each flash you get the rich after reflash so that artificially screws your fuelling so you have to go for a drive each flash to get the offset back into normal range. Annoying. Give this tune a go.

[madkidd007]

Ok, been there done with the idle tuning guides on this forum. They take way to long to go through and so much back and forward with flashing each step. Then after each flash you get the rich after reflash so that artificially screws your fuelling so you have to go for a drive each flash to get the offset back into normal range. Annoying. Give this tune a go.

Thanks I’ll take a look at it tonight. What I’ll probably do is just pull the compare and use your changes in steps so I can see and understand the differences it makes. It’ll help me out and educate me

[madkidd007]

Ok, been there done with the idle tuning guides on this forum. They take way to long to go through and so much back and forward with flashing each step. Then after each flash you get the rich after reflash so that artificially screws your fuelling so you have to go for a drive each flash to get the offset back into normal range. Annoying. Give this tune a go.

so that did help, the surge is non existant but as you can see when i blip the throttle it falls way below desired RPM MOST of the time, it catches but too close for comfort. Im going to look and compare your file changes so i can understand better and see just how far off I wasforum reference idle park then gear no surge but low idle after throttle blip.hpl

[castorjames]

Consider running less idle timing / more idle airflow, that would give you more torke reserve if needed. also idle timing advance tables will help with idle dropping too fast.

copy/paste idle over/underspeed spark tables from 2012 truck or something like that. current ones looks soft

[07GTS]

make the idle adaptive min rpm reference bout 100 or so lower then your idle rpm

[madkidd007]

Consider running less idle timing / more idle airflow, that would give you more torke reserve if needed. also idle timing advance tables will help with idle dropping too fast.

copy/paste idle over/underspeed spark tables from 2012 truck or something like that. current ones looks soft

I’m running 3.50 gears with a 29” tall tire, so don’t need too much.
My spark tables are what gm uses in their crate motor with the same cam so I figure they must know what they’re doing on that aspect. The idle timing I will look into though since gm does idle the crate motor at almost 900 RPM

[smokeshow]

make the idle adaptive min rpm reference bout 100 or so lower then your idle rpm

This.

It will not enter idle mode if your target idle is below the min RPM reference. I'd also put your follower decrement and increment coefficients back to stock for now.

[madkidd007]

This.

It will not enter idle mode if your target idle is below the min RPM reference. I'd also put your follower decrement and increment coefficients back to stock for now.

Back to stock for what? The ecm was a 4.8, I was running a 5.3, now I have a 6.0. There is no stock.