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Thread: Question on Idle AFR vs Coolant Temp on OL SD

  1. #1

    Question on Idle AFR vs Coolant Temp on OL SD

    At work right now so I'm not able to go through my HP Tuners Software and do some digging, I noticed this morning that while in P at Idle before I left the house. my AFR was around 15.3-15.5AFR at around 135 temp. After driving for a bit while sitting at a light I noticed it was running significantly richer 13.5-13.9AFR at around 170 temp. When I got to my destination I put in in Park and my AFR dipped to 10.9-11.2. So my question is, are these tables modified by the airflow tables when doing your idle tuning or is there a modifier for coolant temp? The reason I ask is if I make a fueling Adj to those tables it will either swing way lean or rich at idle at initial start up and then change from there as the truck warms up. My cruise and WOT AFR is on point and where I want them. I'm just trying to track down why I cant get this damn idle in P and Gear dialed in to be consistent. Thanks guys


    EDIT: When I said if I make fueling adj to those tables, I meant to the VE Table. Sorry for the confusion. I had a bunch of work crap going on and was trying to get the post typed out in a hurry.
    Last edited by ninjai_ruken; 12-02-2022 at 03:43 PM.

  2. #2
    Tuner in Training
    Join Date
    Sep 2022
    Posts
    48
    Pretty sure there are IAT and ECT modifier tables on basically every aspect of the tune! Sometimes they do air mass, sometimes EQ, other timing. I'm just learning all this but the more you browse the modifier tables and instead of getting bewildered you take a moment to work out what each does before looking at the next, then you start to see it fall into place.

  3. #3
    Potential Tuner
    Join Date
    Jan 2020
    Location
    Earth
    Posts
    7

    Try this

    [ECM] 12430 - Open Loop F/A vs. Coolant Temp vs. MAP: This table is used to determine the commanded AFR when in open loop mode. It divides the Stoich AFR value. AFR is determined by 14.7/table value. Example: 14.7/1.30 = 11.3 AFR
    GM_P01 12430.jpg

  4. #4
    Quote Originally Posted by leovagle View Post
    [ECM] 12430 - Open Loop F/A vs. Coolant Temp vs. MAP: This table is used to determine the commanded AFR when in open loop mode. It divides the Stoich AFR value. AFR is determined by 14.7/table value. Example: 14.7/1.30 = 11.3 AFR
    GM_P01 12430.jpg

    I've messed around with this table and my idle AFR is still always WAY off usually starts out fine until warm, I've even gone as far as to set that entire table to 1. Ill post a log and tune file as soon as I get some good data. I would think that setting that entire table to 1 it should not effect whats in the VE Table.

  5. #5
    Potential Tuner
    Join Date
    Jul 2021
    Posts
    5
    Let us know if you figure this out. I'm having the same problem with my sbe 5.3 cammed/turbo etc.. OL 2bar os I cant get my actual afr to stay in line with my commanded afr while idling. It just gets richer and richer the longer it idles.