KR logging on 3.6L LFX engines - Page 2 - Chevy Impala Forums
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post #16 of (permalink) Old 08-10-2015
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Retiredpauly, I figured it probably WAS a typo, but just wanted to add a warning, just in case someone found a "race fuel" additive of some type that contained it and figured it would be OK or beneficial to use the stuff.

2015 Crystal Red Impala LTZ V6
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post #17 of (permalink) Old 08-10-2015
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Originally Posted by jtrosky View Post
Yeah, I probably shouldn't worry about it since it does it from the factory with the factory tune, but since I don't need to squeeze every last drop of power from the car, I decided to attack the problem a little. It's amazing how much the KR can be reduced/elminated by just removing a degree or two of timing here and there. Now, the most I ever see (so far) is 4 degrees - and even that is rare - it's usually 2 or less now. I've also started to tune the IAT (Intake Air Temp) spark modifier tables so that the hot weather (IAT's over 95F) don't affect it so much. Surprisingly, the IAT tables weren't used at all from the factory (or with the Overkill tune).

I've also settled on a compromise between the stock and Overkill tunes regarding how fast it restores timing when it does detect knock - the stock tune restores timing VERY slowly and the Overkill tune restores it VERY quickly. I decided to go with a "middle of the road" value so that it restores timing relatively quickly, but not as quickly as the Overkill tune. I've been doing a LOT of logging with HPTuners and I've learned so much about how these cars work - I mean I've really learned a LOT! :-) Very cool stuff...

I've found that the car defaults to the High Octane table and only moves towards the Low Octane table if and when it experiences knock. Since I saw KR so often with 93, I can only imagine how much timing gets pulled with 87 octane! There is no doubt in my mind that this car runs better with 93 octane fuel.

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I remember about a year ago we both were a little hesitant to jump into the tuning world but I'm sure glad I did. Good call using the IAT table...I honestly never messed with that because I figured the car wouldn't use it since the stock values are all 0...might have to give that a try because the temperature seems to be the biggest culprit for KR for me.
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post #18 of (permalink) Old 08-10-2015 Thread Starter
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Yeah, I spent a lot of time review logs and used the IAT table and IAT multiplier table to get a good mix of where and when to removing timing based on temps. Someone on the HPTuners board recommended it. What's nice is that there is an "IAT Advance" PID so you can actually see exactly when and how much timing it's removing when reviewing logs (so it definitely does work).

Still need to dial it in a little more as I drive in some more temperatures, but so far it's seemed to help quite a bit (between it and modifying the high/low spark tables themselves in a few places - especially the 1200 RPM row!

I never in a million years planned on getting into car tuning, but it's been an extremely rewarding experience. I'm a computer guy by trade and I've always loved exploring every option when dealing with computer stuff (first thing I do when using a new device or new app is explore all of the options and mess with them), so tuning these computerized cars is a dream come true - TONS of options!!! :-)

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post #19 of (permalink) Old 10-17-2015 Thread Starter
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Quote:
Originally Posted by retiredpauly View Post
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Do I understand you that you can watch this happen real time as your driving ?
Yes, you can watch it in real time (along with TONS of other data) or, probably even more useful, is that you can "replay" the data logs at your leisure. And not just play the logs back at normal speed - you can play it back at multiple different speeds and even more useful, examine the data frame-by-frame. And you can also define "histograms", which allow you to easily identify peaks and problem areas without having to search through the logs. The HPTuners Scanner application really is a game-changer. I always thought that Torque Pro was awesome - and it is cool - but, the HPTuner scanner app makes Torque Pro seem like a toy in both the amount of data that you can review and the ways that you can review it.


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Originally Posted by bignick2015 View Post
These 3.6 cars (the 9th gen more so than the 8th) seem to be tuned to stay in a high gear as much as possible for economy, so tuning the transmission might help elminate some KR (by providing a quicker kickdown at less throttle %).
I completely agree. In fact, I've altered the transmission shifting tables quite a bit to do exactly what you talk about. I don't go into 5th and 6th gear as quickly as stock and I also release the TCC lockup clutch and/or downshift with much less throttle input now. Really does make a significant difference in the overall responsiveness of the car - it just reacts to throttle input so much better now.

Still messing with my tune - I just can't quit - I *love* logging data and trying new things. Now that I've got the timing and trans shifting refined just like I like it, I'm now going to start messing with:

- Reducing torque management slightly during upshifts - basically, I'm going to start by removing 10% of the upshift torque management during low RPM, low torque shifts and removing 5% of the upshift torque management during mid RPM, mid torque shifts. Plan on leaving torque management intact for high RPM, high torque upshifts.
- Going to try disabling "Torque Shaping" - supposedly, this will make the throttle feel a lot more like a throttle-cable driven throttle - more "direct" feel between pedal and throttle.
- Going to try disabling "Discrete Shift Torque" - basically, when this is enabled, the transmission will use a pre-defined pressure value for shifts for a given torque range (low, mid, high) - supposedly, this allows the transmission to learn the pressures quicker and easier. Some people like leaving this enabled and others like disabling it. Curious to see what difference it makes. In my mind, I'd want the computer to use the actual shift torque values instead of just "estimating" it like it does when Discrete Shift Torque is enabled.
- Going to enable true tap-shifting instead of the range-select version of tap-shifting that the Impala uses by default. Basically, this will allow me to select the gear that I'm in instead of just allowing me to select the highest gear that it will use. May be useful in the winter, so that I can start off in 2nd or even 3rd gear, for example.

Lots of cool, fun stuff you can do!!!
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post #20 of (permalink) Old 10-17-2015 Thread Starter
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Of course, one thing that should be mentioned in regards to Torque Pro vs. HPTuners monitoring - using Torque Pro is a LOT less "intrusive" since you can use it on a phone or small tablet without wires (uses bluetooth).

The HPTuner scanner application requires a Windows device and uses a thick cable between the OBD-II port and the Windows device (I use an Asus T100 tablet/keyboard dock combo, which works really well). I usually just put the Asus on the passenger seat so that I *can* review it in real-time if desired - but you could also just put it on the back seat floor or something and review the data later. Honestly, being able to review the data later, in the comfort of your home, for example, is the best way to use the data anyway. But it's nice having the ability to monitor real-time in certain situations as well.

Really, they are two different tools that can both be used in different situations. One "compliments" the other. :-) But for *true* data logging and analysis, HPTuners is the much better tool. For quick data review or code scanning, Torque Pro makes more sense.
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post #21 of (permalink) Old 10-17-2015
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How do you like the true tap shifting? I've been thinking about enabling it on mine. Does it only function in Low or do you have to paddle shift in D also?
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post #22 of (permalink) Old 10-17-2015 Thread Starter
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Haven't enabled it yet... I do know the correct settings to enable it, but just haven't done it yet. I'm not sure if you can set it up to work when in drive or not, but I think you can - have to re-visit the info on HPTuners...
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post #23 of (permalink) Old 10-20-2015 Thread Starter
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FYI - here is a link to the exact settings you need to enable true tap shift (this is from the Camaro forums, but I believe that this will work on the Impala too):

2ls with Sport Mode and manual mode - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums - Camaro5.com

Basically, the Camaro LS comes stock just like the Impala - with the ERS is manual mode. Apparently, these settings will make the Camaro LS act just like the Camaro LT, which allows for true tap shift from the factory.

It's funny, all of the "pro" tuners were telling the Camaro folks that it couldn't be done - and then some guy just tried setting the trans setting to the same values as the Camaro LT and sure enough, it worked!

EDIT: By the way, this should also let us setup a "sport" mode, where you can make the shifts quicker/firmer and re-adjust shift points. Basically, when you go into "M"anual mode, you'd be in "Sport" mode (which would still shift automatically, but use the "sportier" shifts) - unless/until you use one of the paddle shifters - then you'd switch into true "tap-up/tap-down" mode (no automatic shifts). If you wanted to get back into automatic "Sport" mode, you'd hold the upshift paddle for 2-4 seconds and it would return you to "Sport" mode... Of course, while in "D"rive, shifting would operate normally. Pretty cool setup! Will have to try it myself soon....

Last edited by jtrosky; 10-20-2015 at 12:41 PM.
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