Althought I think I am on the right way to fixing this, I never did find out from anyone what truly is happening in the PCM when I click the commanded AFR button. Also, clicking the commanded AFR button doesn't fix the dipping idle issue like I once thought it did.

 

KBracing is EFI fwiw. Nice to see that's helping, headed in the right direction feels REAL good when tuning. Still interesting about the whole commanded button. The cracker table was just an observation, I didn't mean to make it sound as if that would solve the issue. Cracker doesn't effect sitting still stuff, it just helps give your rpm a "landing pad" coming to a stop IMO. Just "another" item to look into getting right or close to right.

 

Using the AFR control on the scanner will change the Commanded AFR to what you want, not necessarily to the AFR you specify. In open loop you ECM is commanding any where from 13.2-14.68, and while in closed loop the ECM is commanding 14.68 with the help of the O2 sensors to keep it there. And during WOT it will command what the PE Table asks for (I set it to 1.14 = 12.8, OEM have it set as much as 1.25 = 11.7). By setting the AFR to say 13.0 on the scanner, theoretically you will see 13.0 on a wideband. But if the tune is slightly off, it will bring it up or down from that point. Say you are in closed loop, your truck is showing 14.5 AFR. That is good, but when you hit select 13.0 in the scanner AFR, the truck goes into open loop and tries to command 13.0, but you are seeing (for example) 14.5. Well that is good, but you are 12% lean. You would need to command 11.60 to get 13.0 in this scenario. This is why tuning the VE and MAF (not the PE and IFR) is crucial to engine operation. I have seen cases where the MAF failed or the O2s failed, but the owners never knew it as it drove exactly how I tuned it. So if the fuel tables are set right, that AFR Commanded button on the scanner will result in the actual AFR matching what you are requesting.

Hope that helps.

 

I am EFILIve, but i just looked and it looks like I raised them about 2.3 to 2.5 (to 8.1) grams/sec from 176* ECT on up from stock. Also blended the table on up in the lower temps to match. (it's table B4307 in case you have ever DL'ed EFILive software)