E67 Airflow Final Minimum tuning process

Looking for advice from the tuning geniuses here!

doing some tuning work on a supercharged LS3 crate engine with an E67 ECU. I'd like to fine tune the Airflow Final Minimum values to see if that will help with an idle issue. Earlier OSs had a similar table that listed airflow vs coolant temp. This OS (12638778) has this Airflow Final Minimum table in General/Idle/Airflow and it's airflow vs rpm vs gear (PRN6,5,4,3,2,1). There is no gear input in this case so the ECU always references Park (I think...).

What is the recommended process for recording airflow given that there is a separate table with coolant temp modifiers (ECT MULT)? Set up a histogram for airflow and just record the values at a stable temp? Are these Airflow Final Minimum values inclusive of the ECT Mult calculation? Meaning, if I measure the actual airflow and paste them into the appropriate RPM cells in the Airflow Final Minimum table, are they going to get modified by the multiplier so that they end up drastically wrong?

Any advice will be appreciated!


THANKS

G

My method is based on the russK method for gen 3's.

With your fuelling pretty good...

Using the VCM scanner set the idle rpm at 650, 800, 1000 & 1200 for 30 seconds each time on a fully warmed up engine.

Using the averaged dynamic air flows recorded in the scanner for each rpm band; put those into your min air table with the exception of the 1200 rpm cell. In that cell, put in less than the recorded dynamic air (but still more that the 1000 rpm cell). This helps with blips returning smoothly to idle speed.

To set the ECT multiplier change your tune so every idle rpm table is 1000rpm. The colder the weather the better. Do an idle run from engine cold to hot. Log your dynamic air vs minimum air and average them over 10 second rolling blocks I.e pidNumber.avg(10000). The 2 curves in the scanner should be very close to overlapping and follow each other on the way. When they do, you know you have the multiplier dialled in sweet.

Depending on your OS, if the multiplier in the around 90degC cell is 0.25 then the formula for minimum air flow is Min Air Flow vs RPM table x (ECT Multiplier / 0.25)

Quote:

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Originally Posted by hjtrbo

My method is based on the russK method for gen 3's.

With your fuelling pretty good...

Using the VCM scanner set the idle rpm at 650, 800, 1000 & 1200 for 30 seconds each time on a fully warmed up engine.

Using the averaged dynamic air flows recorded in the scanner for each rpm band; put those into your min air table with the exception of the 1200 rpm cell. In that cell, put in less than the recorded dynamic air (but still more that the 1000 rpm cell). This helps with blips returning smoothly to idle speed.

To set the ECT multiplier change your tune so every idle rpm table is 1000rpm. The colder the weather the better. Do an idle run from engine cold to hot. Log your dynamic air vs minimum air and average them over 10 second rolling blocks I.e pidNumber.avg(10000). The 2 curves in the scanner should be very close to overlapping and follow each other on the way. When they do, you know you have the multiplier dialled in sweet.

Depending on your OS, if the multiplier in the around 90degC cell is 0.25 then the formula for minimum air flow is Min Air Flow vs RPM table x (ECT Multiplier / 0.25)

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hjtrbo,

thanks for the details! I'd like to ask a few follow up questions.

do you happen to have a link to the russK post with his GEN 3 instructions?

Doesn't dynamic air already include the modifications made by the ECT Mult values? Or are you setting that value to 0.25 at your fully warmed temp so that there is no influence from the multiplier?

Regarding setting the ECT Mult: when you say "log your dynamic air vs minimum air, are you talking about a 3D histogram or just a straight time-based log comparing these two PIDs?

Again, thanks for your recommendations!


G

I don't have a link to the original RussK method, but Lowbuck LS on youtube has a video on it. It's for Gen 3 vehicles but I found it applied to my Gen 4 nicely. Another option is to use the GEN 4 idle tuning guide which you can search for on this forum.

With regards to the ECT multiplier; Dynamic air is the result of the multiplier and minimum air flow table working the throttle blade. I.e the air entering the engine.

Just a straight time based log. I do not know if every ECM has the minimum airflow PID available.

Here is an example of what I am saying with the log to check on how close you are with the ECT multiplier and minimum air flow. I have largish cam and my idle is very good. Throttle blip response is excellent & no surging on coast down.
Attachment 105288

Thanks, again, hjtrbo!

This is gold! I can't seem to find a PID for the Base Airflow Minimum, but I'm sure I can figure a way to pull the channel data into excel. Time to give it a whirl!


THANKS


G

BTW--in case anyone is reading this and wants to read the idle tuning guide for Gen IV, I found BigMike42's "Gen4 idle tuning guide" here:

https://forum.hptuners.com/showthrea...ght=idle+guide


THANKS