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Thread: The "Dr. Nopps Hates Knocks Guide"

  1. #1
    Advanced Tuner Dr. Nopps's Avatar
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    The "Dr. Nopps Hates Knocks Guide"

    As you may have seen posted several times under this (V6) section more heavily it would seem: "Why am I getting 4 or even more KR running name brand premium 93 octane fuel on a mechanically perfect car, with the stock tune?" Well, if your motor is N/A (Naturally Aspirated - no turbo or super charger) I just may be able to help you out. After seeing this happen on my own vehicle I began extensive testing. Knowing for a fact nothing was wrong with the car I actually started removing timing from the factory tune only to get dissatisfactory results with little relation to the problem at best. Remembering that a dear friend of mine once blew up a very nicely built engine due to slightly over-fueling led me to look there next. Most of what I had read advised around a 13.0 - 1 AFR on an N/A engine so I looked deep inside my tune, and then it hit me. Math, Seriously! I referenced any tables that would command AFR as well as any of their potentially related adder/subtract/multiplier tables and found several spots in the factory tune where my car was being commanded to run severely rich. Cleaning up these areas worked like a magic bullet for all my KR and I could even add a substantial amount of timing to the areas of my tune that I wanted to, as well as get a far clearer picture for the true threshold of timing advance before actually causing KR. Keep in mind this was written and based around the OS's used on the late 1990's early 2000 V6 cars, but the basic principles could be used for any N/A tune.

    O/L AFR & AFR ADDER TABLES:
    Set these tables up so under relatively normal operating coolant temperature of say 140 degrees or higher there will be no commanded AFR richer than 13-1, we are not concerned with any areas leaner than 13-1 so leave them alone for now.

    PE MODE ENABLE DALAY & HOT PE MODE ENABLE THRESHOLD TABLES:
    Most people set these up to enable PE Mode around 30% or 50% TPS on up, depending on terrain and MPG requirements.

    ADD VS. TPS:
    Set or leave set to 0.

    PE MODE BASE AFR:
    As with the O/L tables earlier, set up so under normal operating coolant temps you aren't any richer than 13-1. You can start the normal operating temperature thresholds cooler here than in your O/L tables without having adverse affects on emissions diagnostics.

    PE MODE ADDER VS. TIME TABLE:
    I have the 0.0 and 1.6 second columns set to 0.200 from 800 RPM and higher and zeroed everywhere else on this table. This commands the AFR slightly leaner than my optimal target just around a second and a half so it doesn't slam down there too fast and briefly over-fuel. If you accurately re-tune your MAF for cruising and WOT, you may be able to reduce or even eliminate your need for this table all together. (NOTE: This table should be zeroed out all together while MAF tuning)

    ACCELERATION ENRICHMENT WOT DISABLE:
    This feature sounds like a double negative, and may seem confusing at first but set this to enable. This will allow this feature to kick in and prevent acceleration enrichment from adding any more fuel on top of your target AFR for PE Mode, which can definitely cause over-fueling.

    COT AFR:
    Set a 13-1 AFR for the WOT lb/hr range of this table and a stoich oriented AFR for the cruising lb/hr range whether you have this feature enabled or not.

    TCS METHOD AFR:
    Set Modes 1 through 7 for 13-1 AFR whether TCS is enabled or not.

    GEAR & DIFFERENTIAL ABUSE AFR:
    Set to 13-1 AFR whether these abuse modes are disabled or not.

    Well that about sums it up for now anyways. All types of engines run differently so you may even be able to get away with running something slightly different than 13 to 1 AFR under WOT depending on the thermostat you use, effectiveness of your cold air induction, ect. But I've found 13 to 1 to be the best place to start. This won't help every single person out there chasing your KR woes, but for a surprising majority of the N/A V6 crowd it may be just what the doctor ordered.

    P.S. Also please see this very good read on related subject:http://www.hptuners.com/forum/showth...s-under-cruise
    Last edited by Dr. Nopps; 08-18-2014 at 04:10 AM.

  2. #2
    Advanced Tuner Japeatr's Avatar
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    good post

    384whp/303wtq
    Built 2.0LSJ: TVS w/2.6, 1000cc, Stage 2 cams, custom fuel system, E85, Dual Pass, 3"intake, 3" Catless exhaust, CIA midlength Header

  3. #3
    Advanced Tuner ZeroBoostBuick's Avatar
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    I wonder why more people don't try this because it got rid of the majority of the KR in my 2002 GP-GT... I didn't understand why I couldn't tune out all the KR from this car because I tuned other 3.4/3.8 v6's and getting rid of the KR was easy with just fueling adjustments, but not with my current ride... then I read this post and the majority of the KR is GONE !!!