Results 1 to 6 of 6

Thread: high octane low octane

  1. #1
    Tuner Howes's Avatar
    Join Date
    Apr 2015
    Location
    NH
    Posts
    130

    high octane low octane

    So my personal 06 lq4 hd that i have been tuning and tuning and tuning some more. I tuned my high octane tables to where it only gets kr on 87 (what i run it's a daily driver) in two small spots and not even all the time depends on ambient temp if i am climbing a hill or have a load in the bed.I then put the stock low octane table back in and even had to back it down in those two spots due to kr until i got none. that being said...I read somewhere i don't remember where it uses high octane until it sees kr then it slowly learns calculates and flips from high to low as needed but uses high except where it learns the kr is. But then I read gen4 motors use high until it reads kr then just flips to low and stays there until a refueling event occurs. That being said it feels as if every time i fuel up it gets zippy for a little while then slowly goes back to less zippy. It seemed to stay zippy when i filled it with 93 for fun and got zero kr. but maybe it was in my head. I know i don't have a gen 4 but can someone present me with a link to the facts or let me know for sure which is right. It doesn't effect how I'm going to tune my truck just want the theory and facts.

  2. #2
    Senior Tuner
    Join Date
    Jun 2004
    Location
    405
    Posts
    2,287
    It interpolates between the 2 tables. Log Knock Learn Factor to see where you are.

  3. #3
    Tuner Howes's Avatar
    Join Date
    Apr 2015
    Location
    NH
    Posts
    130
    k so i guess you may be right no one is saying otherwise. i thought that's how it worked on gen 3 motors but there is no owners manual explaining how things work with this program so all i have had was different posts and websites to go by. can anyone let me know what the name of the book is that is recommended for this? ill log it to see where i end up.

  4. #4
    Why not copy your high table over to your low one and leave it that way. Then it wouldnt after which table the pcm pulled from. If you are only getting kr in a couple cells, and only like 1 or 2 degrees, then it won't hurt anything. My Brother in Law has an 04 gasser that has kr in stock form and has for years with no issues. I also logged my 2012 express van stock and it had knock. On a stock motor, knock of 1 or 2 degrees is not an issue.

  5. #5
    Someone is probably going to hang me for that comment. I have seen too many stock tunes with knock at some point to worry about a couple of cells.

  6. #6
    Tuner in Training
    Join Date
    Feb 2015
    Location
    Louisiana
    Posts
    23
    I've been seeing this a lot. 87 octane is garbage at least run 89. Especially in older pcms. Headers add to knock so make sure its not false knock.