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Is it possible to have large knock sum generated from hard shifting?

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Old Jul 11, 2011 | 07:52 PM
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duranvw's Avatar
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Is it possible to have large knock sum generated from hard shifting?

I finally have my evoscan working today! AEM wideband logging via serial>usb, installed jdm3bar map sensor and configured for 2byte load.

I just logged one good pull through 2nd to 4th and I have a couple logs of knock sum of 36, then 12 the next cell. I think this happened right at 7000rpm when I shifted, is it possible this is from hard shifting or is this real and should I start adjusting for it? The timing looks to be quite high at these points.

I attaced a screen shot of part of the log, this is my first time logging with everything working, I have watched r3compiles videos a couple times and have a good basic understanding just looking for some input...

Also definately know I have a boost leak... testing for that this weekend just put together a boost leak tester tonight.

(the forum auto adjusted the size if the image, made it a little harder to read)
Attached Thumbnails Is it possible to have large knock sum generated from hard shifting?-log.jpg  
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Old Jul 11, 2011 | 08:19 PM
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I THINK I remember reading a thread a while ago that mentionned that someone had experienced this sort of knock during a pull, and when they used detcans to check if it was real, it turns out it was. There's not much that can be done about it though, can you post your timing map? I've found that lowering timing from 100-200 load at 5k+ rpm (basically, the load/rpm area you hit during a shift) can help quite a bit with shift knock, however that was for NLTS shifting.

On a side note, you're logging more items than you need with evoscan and it's slowing down the process a whole lot. Uncheck whatever you don't need to be logging (ie coolant temp, air temp, speed, airflow, etc)
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Old Jul 11, 2011 | 09:18 PM
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I should have mentioned its on the stock tune still, only mod really is TBE, but also have a boost leak at the moment.

That's a good point, I will make some more runs with minimal data being logged for a bit more accuracy. I can post my timing map still if needed when I get home but I'm quite certain its stock from what I can tell.
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Old Jul 11, 2011 | 10:57 PM
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I look at knocksum as this......if the ecu says knock and its over 100 load......I treat it like knock. Detcans can tell you for sure. Like raptord said you can richen up the map around 7000 - 5000 rpm load from 180-220 and flatten the timing in that area to try and eliminate the shift knock also. Post timing and fuel, who did your tune?
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Old Jul 11, 2011 | 11:48 PM
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when you shift the ecu traces different load areas, so if your map is not properly setup and its tracing high timing areas that were left untouched it will cause real knock.

Last edited by tscompusa2; Jul 12, 2011 at 06:38 AM.
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Old Jul 13, 2011 | 12:24 PM
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Here are screens of my timing and fuel maps, as I said I beleive this is still stock, also a screen shot of a second log...

Again showing a lot of knock at shifting, also Injector Duty % at 90% ++ !! Can that be right? I'm not even making full boost
Attached Thumbnails Is it possible to have large knock sum generated from hard shifting?-highoctanefuel.jpg   Is it possible to have large knock sum generated from hard shifting?-highoctaneignition.jpg   Is it possible to have large knock sum generated from hard shifting?-log2-knock.jpg  
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