COBB AP V3: High A/F Learning and Feedback Knock
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This is a discussion on COBB AP V3: High A/F Learning and Feedback Knock within the Tuning: Electronic Engine Management forums, part of the Tech & Modifying & General Repairs category; Hello I'm in need of some help and insight. I did a log while cruising. I didn't want to do ...

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    COBB AP V3: High A/F Learning and Feedback Knock

    Hello I'm in need of some help and insight.

    I did a log while cruising. I didn't want to do a 3rd gear redline WOT after seeing knocks being recorded on the AP's Feedback Knock gauge. Here's the log:
    https://docs.google.com/spreadsheet/...0E&usp=sharing

    I just re-flashed my car with Stage 1 91ACN less than a week ago.

    I did flash my car before to Stage 1 91ACN v3.0 during the winter months, but had to go back to stock when I had to take the car in to the dealer. During the winter, though, A/F was fairly low adding fuel and taking away fuel averaging within -/+4 and the Feedback Knock was always at 0. Everything looked healthy. I wish I hadn't deleted those logs just so I can compare.

    Now it seems to me with this data log those numbers look funny to me. I've been on this map less than a week and just recently filled up with a full tank of gas a few days ago. Is the car still learning and adjusting to the hot weather?

    Some things to note:
    -2013 WRX with 10,600 miles. Car's engine is stock.
    -I filled up the tank with 91 premium octane (full tank) while the tanker truck was also filling the underground tanks. Might this effect the Knock Feedback I am getting?
    -I live in Las Vegas where Summer's rolling in and temps outside today have been 75-80 degrees and usually gets dusty on my drive back home. I'm thinking my filter needs to be replaced and MAF sensor needs to be cleaned. Would this effect A/F Learning?
    -The knocks seem more active in 5th gear while partially on the throttle and above 2300 RPM (on the freeway).
    -Knock does not occur during normal city driving (4th gear) light throttle. Experienced some rare knocks, but I think that's due to shifting and construction and bumps on the road.
    -There doesn't seem to be anything wrong with the car though. Drives great, but the data logs worry me.

    Thanks for any help or feedback.

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    So I had the AP monitor Feedback Knock on my drive to work this morning. I was on the freeway going about 65mph@3,000RPM and sometimes being aggressive on the throttle hitting 80mph@about 3,500-4,000RPM.

    Throughout the entire commute I only had 1 instance of knock which was -1.4 (probably due to aggressive shift). DAM stayed at 1, and Fine Knock Learn always at 0. A/F Learning stayed about the same, but never above -/+5.

    Car ran great. I should mention it was 60-65 degrees out in Vegas weather.

    Compared to my previous post the drive this morning felt pretty tame with rare feedback knock from the AP. Last drive the Feedback Knock was very aggressive hitting -6 in 5th gear and partial throttle and A/F Learning hitting 6.25 in 80 degree weather. I don't know if it's weather or bad gas or the car getting accustomed to just being flashed to Stage 1 91ACN a week ago.

    I was only able to do 1 pull tonight, but here's the log:
    https://drive.google.com/file/d/0B3o...it?usp=sharing

    No Knock at all. Car looks to be healthy.




    Cruising back home:
    https://drive.google.com/file/d/0B3o...it?usp=sharing

    There's some knock in 5th gear with the throttle partially depressed, but resets to 0 when I lift off the gas.

    Is there anything I should be worried about or should I just toss the AP in the glove-box and quit stressing over it?

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    Registered User LogiMech's Avatar
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    Your google docs aren't working BTW.

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    Quote Originally Posted by LogiMech View Post
    Your google docs aren't working BTW.
    Sorry, do these work?

    3rd WOT:
    https://docs.google.com/file/d/0B3oX...TG8/edit?pli=1

    Cruising:
    https://docs.google.com/file/d/0B3oX...ZWs/edit?pli=1

  6. #5
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    I Support ClubWRX I Support ClubWRX
    Do you have access to 93 RON?

    FYR, from your most recent datalogs, your AFR learning is normal.
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    Quote Originally Posted by zax View Post
    Do you have access to 93 RON?

    FYR, from your most recent datalogs, your AFR learning is normal.
    No 93 here in vegas. I've seen a few stations with 100 oct, though. Would filling up with 100 and 91 be a good idea?

    What do you think of the knocks? They only seem to appear at 5th gear with the throttle partially being depressed and reset back to 0 when I lift off the gas. Knocks don't happen in any other gears. For some reason only 5th gear the knocks are more active.

  8. #7
    Registered User tesla317's Avatar
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    Knocks can be mistaken for many other noises in the engine bay. The most beneficial logs are WOT in 3rd gear. 2,500k -redline. 4th gear for 6speeds.

    The logs need to be short, not long while cruising. I made this mistake when I got my AP, drove myself crazy. Also, cruising in 5th at a low rpm, then giving it throttle and putting it under load will definitely give you odd readings. These are probably inaccurate.

    Go to Cobb's site. They have a lot of info on how to datalog, what to look for, what it all means. Do your research.

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