Camaro E38 Idle Airflow Multi vs. ECT (12198) difference from 2010-13 to 2014+

[acammer]

Hey all. I ran into something unexpected yesterday doing some street tuning on my buddies car. We both have very similar builds, LS3/stick 5th gen Camaro's, near identical GPI camshafts, etc - so when he asked me if I could get him running and driving after his cam swap, I was pretty confident I could. I'm fairly novice, but I've tweaked a bunch on my 2011 car, and a few others, and have learned a lot. I had brought over some of my fuel/spark/airflow numbers as a rough starting place - and on first starts was finding I had nowhere near enough air flow and needed to ride the throttle to keep it idling. I kept adding air to the Airflow Final Minimum table, which I thought would be really close to start with, but wasn't getting a response.

The oddity I found was a dramatic difference in the Idle Airflow Multi vs. ECT. In my 2011 (and what I can find for all 10-13' cars) is that they ramp down as the ECT comes up till they land at 0.25 @ 219*F coolant temp. In the 2014, they ramp down in the same manner, but all the values are a LOT higher, and land at 1.00. Now, the kicker is the Airflow Final Minimum tables are essentially identical (few minor changes in gears 4-5-6 at real light cruise only). I put the stock 2014 multiplier back in and my Airflow Final Minimum table started responding like I was used to.

What I'm trying to understand is what changed to dramatically alter this table? Obviously, the 10-13 cars aren't idling with 25% the amount of air, so there must be something different about the way the calculation actually works on the back-end, right? The only other change I see is the percent max is 2.06% on the 10-13, and 1.98% on the 14+. I admittedly don't really understand how that value works, and usually leave it and the ECT multiplier alone and just work the Airflow Final Minimum. Does it influence the idle airflow calcs that substantially. I've done a little googling on this, but I'm not finding much that helps me understand it. I'd love any inputs or references as I continue to try to learn this gen4 stuff better.

[RobZL1]

That ECT multiplier makes zero sense to me. I know some people have successfully tweaked it to get things working properly during warmup and even on coastdown. But I would love to understand what tables that multiplier actually influences. Like you said, it certainly isn't an actual multiplier. It must either be a coefficient in some other equation(s), or there are a host of other tables/logic out there that apply that we don't see.

[Xjas]

on some OS the ECT multiplier is an adder table in others its a straight multiplier, not sure what year it changed.

[RobZL1]

Well that makes a lot more sense. Thank you!

[Ben Charles]

Leave it how the OS is...