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      08-12-2009, 07:14 PM   #1
ArktisE92
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Procede CAN Knock - How to Interpret?

Been playing around with the datalogging features in the new Procede software and looking into the "CAN Knock" datafield. Does each "1" correspond to an actual knock event, or does this indicate when the DME intervenes to prevent a knock? My butt-o-meter don't seem to have registered a knock when those "1"s were logged...

FYI I've gotten 12 or so of those during a 1/2 hour run. These all occur in low-rev (1.6-1.8k rpm), low-boost (0.4-0.8psi) situations. There are no "1"s during any of my WOT or high-rpm runs.
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Last edited by ArktisE92; 08-12-2009 at 09:18 PM.
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      08-13-2009, 06:06 AM   #2
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Quote:
Originally Posted by ArktisE92 View Post
Been playing around with the datalogging features in the new Procede software and looking into the "CAN Knock" datafield. Does each "1" correspond to an actual knock event, or does this indicate when the DME intervenes to prevent a knock? My butt-o-meter don't seem to have registered a knock when those "1"s were logged...

FYI I've gotten 12 or so of those during a 1/2 hour run. These all occur in low-rev (1.6-1.8k rpm), low-boost (0.4-0.8psi) situations. There are no "1"s during any of my WOT or high-rpm runs.
Without me getting into an argument with anyone, I have logged a whole lot over the last 3 months and I can tell you that the "Actual Knock Value" is extraordinarily unreliable. Do a search and you will even see Scalbert took it out of his recommended data log because of how eroneous it is. I see knock values of 1 when the car is idling many times, and when I an cruising, then none when I go WOT.
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      08-13-2009, 09:30 AM   #3
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Originally Posted by Former_Boosted_IS View Post
Without me getting into an argument with anyone, I have logged a whole lot over the last 3 months and I can tell you that the "Actual Knock Value" is extraordinarily unreliable. Do a search and you will even see Scalbert took it out of his recommended data log because of how eroneous it is. I see knock values of 1 when the car is idling many times, and when I an cruising, then none when I go WOT.
yep same findings here
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      08-13-2009, 12:25 PM   #4
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Yep... Not accurate due to sampling rate limitations. That is why there is no mention of it in our custom tuning documentation. Monitoring ignition advance is a much better method to determine the presence of knock control activity.

Shiv
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      08-13-2009, 12:32 PM   #5
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Quote:
Originally Posted by ArktisE92 View Post

FYI I've gotten 12 or so of those during a 1/2 hour run. These all occur in low-rev (1.6-1.8k rpm), low-boost (0.4-0.8psi) situations. There are no "1"s during any of my WOT or high-rpm runs.
I was driving crazy with this as well...I was seeing knock indications with partial throttle below 33% and boost no more than 1psi. I'm happy this has been clarified.

Shiv, If you are positive that the ignition advance is much more reliable can you please explain all these oscillations happening while cruising at 3K-4K revs ,boost no more than 1,5psi & throttle bellow 35% at all times ?
It seems that the car knocking badly (unless i dont read the logs properly). I'd like to underline that the below logs/runs has been made with Ignition Advance settings at 100%



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Last edited by Panoz; 08-13-2009 at 01:04 PM.
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      08-13-2009, 01:17 PM   #6
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Never heard the term ignition advance oscillation before. I think you'll find that you will see the same igniton advance activity on a completely stock tune. Let me clarify my pevious comment about ignition advance monitoring: it's the most useful indicator of knock retard activity when running under full boost/WOT. At partial throttle, you are going to see it move all over the place. That is normal. Don't bother trying to over-analyze engine data during cruise conditions. There's just too much stuff going on.

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      08-13-2009, 01:26 PM   #7
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Quote:
Originally Posted by shiv@vishnu View Post
At partial throttle, you are going to see it move all over the place. That is normal.

Shiv
This is understood now. The ignition drop outs should be consider only under full throttle.

The "ignition advance oscillation" ,actually refers to the graph's drop outs. Sorry for the poor expression.

So, as the CAN Knock is not reliable , should we consider that the engine knocks EVERY time we see these "drop outs" on the graph?
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      08-13-2009, 01:38 PM   #8
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Quote:
Originally Posted by Panoz View Post
This is understood now. The ignition drop outs should be consider only under full throttle.

The "ignition advance oscillation" ,actually refers to the graph's drop outs. Sorry for the poor expression.

So, as the CAN Knock is not reliable , should we consider that the engine knocks EVERY time we see these "drop outs" on the graph?
Under the 3rd gear testing procedure outlined in the documentation, it's prudent to assume that ignition drop outs are evidence to knock control activity which is triggered by knock of varying severity. The idea behind the PRocedes proactive ignition control method is that this knock (if/when it occurrs) will be minor/mild since the engine never sees more than a small amound of over-advance.

Shiv
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      08-13-2009, 01:42 PM   #9
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Quote:
Originally Posted by Panoz View Post
This is understood now. The ignition drop outs should be consider only under full throttle.

The "ignition advance oscillation" ,actually refers to the graph's drop outs. Sorry for the poor expression.

So, as the CAN Knock is not reliable , should we consider that the engine knocks EVERY time we see these "drop outs" on the graph?
What you are observing in your logs is normal behavior. The ECU is bumping up timing to the knock threshold and quickly backing off. This same mechanism is at play during wide open throttle runs and is the same mechanism that advances timing when you dump in race fuel.

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      08-13-2009, 01:45 PM   #10
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That's a good one. The close loop-ish ignition advance behavior is based upon feedback from internal engine torque calculation, not sonic knock noise. At light load, advancing up to the point of knock will result in excessive over advance due to the shape of the MBT curve. That's bad.

Shiv
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      08-13-2009, 02:06 PM   #11
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Quote:
Originally Posted by shiv@vishnu View Post
That's a good one.

Shiv
So, if I take a V3 on Stage 3, do a bunch of runs on 91 octane, and without changing anything add 100 octane, what will I see happen on the dyno?

Mike
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      08-13-2009, 03:14 PM   #12
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Quote:
Originally Posted by shiv@vishnu View Post
Never heard the term ignition advance oscillation before. I think you'll find that you will see the same igniton advance activity on a completely stock tune. Let me clarify my pevious comment about ignition advance monitoring: it's the most useful indicator of knock retard activity when running under full boost/WOT. At partial throttle, you are going to see it move all over the place. That is normal. Don't bother trying to over-analyze engine data during cruise conditions. There's just too much stuff going on.

Shiv
Shiv,
Did you ever take a look at the datalogs I emailed you? Thanks.
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      08-13-2009, 04:17 PM   #13
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Quote:
Originally Posted by Mike@N54Tuning.com View Post
So, if I take a V3 on Stage 3, do a bunch of runs on 91 octane, and without changing anything add 100 octane, what will I see happen on the dyno?

Mike
If you did it, I wouldn't event guess. But I have and will post the results up tomorrow. Along with datalogs.

Shiv
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      08-13-2009, 04:18 PM   #14
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Quote:
Originally Posted by usc335 View Post
Shiv,
Did you ever take a look at the datalogs I emailed you? Thanks.
Not yet I'm afraid. Been in NJ for the last few days. Just touched down in CA a few min ago. Got a lot of email to catch up on tomorrow at work
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