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Author Topic: Acceptable limits for knock voltage  (Read 92444 times)
Rick
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« Reply #15 on: March 15, 2011, 05:30:35 AM »

This is a huge topic, always causes of debate.

Firstly, knock isn't as dangerous as often people make out.  It can kill and engine pretty quickly especially when it leads to pre ignition, but light knock has virtually no effect on engine durability. 

You need to train your ears for knock with det cans, but you can clearly hear the onset of det through the head phones even at 7k.  There is a slight change in engine tone too.  I have never damged an engine yet using this method - so fingers crossed!  I'm actually tempted to disable knock control completely, but not going to - not yet anyway. 

Last night, I increased the knock threshold by 10% on all cylinders.  Not done any logs yet, but will be interested to see what comes of it.  It would be nice if the timing was more stable - the CF can jump about a bit, which I don't think is a true representation ok what is actually happening in the engine.

Rick

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carlossus
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« Reply #16 on: March 15, 2011, 09:08:40 AM »

The tune I'm using has KFKEx raised slightly on all cylinders from stock, I assumed this was normal practice but it makes me worry a little that my CF's are no longer representative of reality.

To that end I'm interested in your results.

@Silentbob, are the knock voltages post-filter & intergation or representative of the raw signal?

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Rick
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« Reply #17 on: March 15, 2011, 10:06:48 AM »

Carlossus - how much have they been changed by?

The voltage is a raw signal. 

Rick
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carlossus
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« Reply #18 on: March 15, 2011, 11:20:54 AM »

+12.5% across the board. My CF's are usually <6-7 at full load.

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Rick
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« Reply #19 on: March 15, 2011, 02:10:54 PM »

I think that's probably close to optimum.  Just been out with mine at +10% and i've  probably gained a couple of degrees.

Rick
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NOTORIOUS VR
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« Reply #20 on: March 15, 2011, 04:50:10 PM »


I have never used det cans, but how do you seperate normal engine noise on 6000+ RPM from knocking noise without cylinder pressure sensors?

It's actually very easy... Det cans + the human brain are very capable of determining knock sounds even @ 30psi/8000+RPM.

I always use det cans to tune cars with standalone, even on the dyno.
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judeisnotobscure
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« Reply #21 on: March 18, 2011, 04:25:16 PM »

what are the memory addresses for KFKEx on the mbox?
i would like to add this to my xdf as well.
thanks.
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nyet
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« Reply #22 on: March 18, 2011, 06:08:07 PM »

what are the memory addresses for KFKEx on the mbox?
i would like to add this to my xdf as well.
thanks.

should be relatively easy to find. I'll look for them this weekend time permitting if nobody else posts em up.
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judeisnotobscure
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« Reply #23 on: March 18, 2011, 07:10:44 PM »

i'm looking for them as well... this is new to me so i probably won't find them.
would you start with the potential maps in winols or would you look elsewhere?
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Rick
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« Reply #24 on: March 19, 2011, 04:20:56 AM »

I've attached an XDF with them in.
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nyet
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« Reply #25 on: March 19, 2011, 12:28:26 PM »

I've attached an XDF with them in.

Thanks Rick!
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ME7.1 tuning guide (READ FIRST)
ECUx Plot
ME7Sum checksum checker/corrrector for ME7.x

Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience.
silentbob
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« Reply #26 on: March 20, 2011, 04:39:58 AM »

The tune I'm using has KFKEx raised slightly on all cylinders from stock, I assumed this was normal practice but it makes me worry a little that my CF's are no longer representative of reality.

To that end I'm interested in your results.

@Silentbob, are the knock voltages post-filter & intergation or representative of the raw signal?



It's not that easy. The knock voltage you see in VCDS, ECUx s.o. is the variable rkrn which is used for diagnoses purposes. It's the reference integral value muliplied with 64/(2^amplification factor).

On the hole knock topic. Maybe I'm a bit of a sissy but if you have seen what consequences even minor hardware changes can have on the previously calibrated knock recognition you act a bit cautiously here.
When I have some time I will give the det can method a try and compare it to the pressure sensors. 
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silentbob
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« Reply #27 on: March 20, 2011, 03:15:50 PM »

Something I want to add:
I have noticed that almost everyone is running ignition angles on high load which result in permanent ignition retard per knock control.
Is everyone aware of the fact, that the knock control has also an adaption function which learns values if you do this?
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carlossus
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« Reply #28 on: March 20, 2011, 03:30:22 PM »

Can you elaborate a little? Ignition is retarded by adaptation at those load points where  correction is always required?
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judeisnotobscure
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« Reply #29 on: March 20, 2011, 03:32:56 PM »

^x2
is this an intergral function of kr? In which map would you find these values?
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