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Rob W

Knock Control G4+

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I have an Ej 25 with forged pistons etc.

Setting up the knock control with the suggested frequency at 6kHz. It has been set up to allow the ecu to pull 3 degrees timing out. The thresholds have been set at 500 for setting up purpose.

It is my understanding that once you have the engines noise profile on a clean run you set the thresholds 20% above for the load rpm ranges but it should not be pulling timing until the threshold is reached.

For some reason it is pulling between 1-2.5 degrees out at random times at half of the threshold levels. Is it hearing knock below the threshold and pulling it out or should it not be doing that?

Also the cylinders are paired for wasted spark 1,2 and 3,4. The way the knock sensor is positioned on the Ej is difficult in regard to setting the gains to get them even as it is closer to 2 and 4 than 1 and 3 which gives odd distances for the cyl gain settings to even them out. Is there a trick to setting these where you do each cyl individually or turn one or two of them off ?

 

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7 hours ago, Rob W said:

For some reason it is pulling between 1-2.5 degrees out at random times at half of the threshold levels. Is it hearing knock below the threshold and pulling it out or should it not be doing that?

It will only remove timing once the threshold is exceeded.  It could be you are observing the wrong parameter, or possibly a setup problem, or sometimes I have seen a situation where the logging is not fast enough to capture the small spike in noise above the threshold. Post a log and map so we can take a look.

 

7 hours ago, Rob W said:

Also the cylinders are paired for wasted spark 1,2 and 3,4. The way the knock sensor is positioned on the Ej is difficult in regard to setting the gains to get them even as it is closer to 2 and 4 than 1 and 3 which gives odd distances for the cyl gain settings to even them out. Is there a trick to setting these where you do each cyl individually or turn one or two of them off ?

You cant do individual cylinder knock control with wasted spark ignition, you can only control the paired cylinders as a pair.  From the help file: "Gains are relative to the Cylinder Allocation, and not the actual cylinder. Gains relating to allocations not defined have no effect."  You should only have Cyl 1 and Cyl 3 allocations enabled and only the cyl 1 and cyl 3 gains will work.

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I also have an EJ25 with forged pistons etc... 

I found that my engine 'background noise' was too 'noisy' to have a threshold of only +20%. 

I also noticed a momentary increase in noise during the transition from 'on throttle' to 'off throttle' (clearly heard on det cans and visible in screenshot attached).

Cold running also produced different noises to hot running (due to forged pistons I guess?), not that I was driving it hard when cold!

When inducing controlled knock to test my setup, I could easily detect knock whilst not giving false knock detection.  See attached for threshold vs cylinder noise that worked for me.  Note, where the threshold is exceeded, throttle is 0%, so knock system is inactive and timing is not pulled.

Not sure if that helps!

image.thumb.png.14e023be056949f4e441a65fdf9ce3f1.png

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Thanks for the replies. Thanks Adam, that clarifies the allocations and gains.

I am logging  "I Trim cyl1 &3". The threshold setting is at a flat 500 for getting the gains and noise profile set up. I have had ears on it but haven't turned the Ignition Retard limit back to zero as I wanted to see what it is doing. Just trying to get my head around why the I trim is showing retard below the threshold. I'll attach a log screenshot and set up shot below.

Knock set up2.JPG

knock set up.JPG

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Hi Timmy,

I have the cylinder allocations set up 1,2 and 3,4. Do I actually need to turn cyl 2 and 4 off?

I won't let me post log files only screen shots.

 

cyl allocations.JPG

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Hi Rob,

Firstly, my experience is limited to my own car only... but I was puzzled why you were only logging/showing knk level for 2 cylinders?  I understand wasted spark, but surely you need to monitor cylinders 2 and 4 to set the gains in the same way as you have for 1 and 3?  Otherwise these may be exceeding your threshold and causing timing to be pulled?

 

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On 7/6/2018 at 7:36 AM, Rob W said:

Thanks for the replies. Thanks Adam, that clarifies the allocations and gains.

I am logging  "I Trim cyl1 &3". The threshold setting is at a flat 500 for getting the gains and noise profile set up. I have had ears on it but haven't turned the Ignition Retard limit back to zero as I wanted to see what it is doing. Just trying to get my head around why the I trim is showing retard below the threshold. I'll attach a log screenshot and set up shot below.

Knock set up2.JPG

knock set up.JPG

 

In this case I think you probably are exceeding the threshold but just the logging is too slow and doesnt show some small/short spikes above the threshold.  What frequency were you logging at?

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12 hours ago, Adamw said:

 

In this case I think you probably are exceeding the threshold but just the logging is too slow and doesnt show some small/short spikes above the threshold.  What frequency were you logging at?

6kHz. It shouldn't be I pulled 3deg out of the positive kPa MAP across the board to set it all up. I've got a driver today so I'll turn the whole thing off and have a better listen to it and report back.

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18 hours ago, TimmyD said:

Hi Rob,

Firstly, my experience is limited to my own car only... but I was puzzled why you were only logging/showing knk level for 2 cylinders?  I understand wasted spark, but surely you need to monitor cylinders 2 and 4 to set the gains in the same way as you have for 1 and 3?  Otherwise these may be exceeding your threshold and causing timing to be pulled?

 

Hi Timmy,

It's because with the cyl allocations set up like that the numbers for each pairing are exactly the same when I log them.

 

Rgds Rob W

Capture.JPG

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Hi Rob,

Interesting... In that case, I'm out of my depth, I will leave you in the hands of those who know...

Couple of final thoughts...

You can log to ECU at 100 Hz, that might show peaks that are 'missed' by laptop logging?  

You can use Knk Ign Trym Cylx to show where timing has been pulled.

I'll keep watching this post out of interest though............

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Thanks Timmy, I'll try logging to the ecu at 100  Hz.

I had the car on the road with a driver today, I turned the ign trim back to 0.5Deg with some det cans on it. It was still pulling small amounts of timing without anything audible.

I've been looking at the spots on the I trim tables where it is occurring it's at half of the threshold and no audible knock

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How about putting a volt meter on the output of the knock sensor to see if its actually putting out voltage and if you see it spike at all when your doing a pull?

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On ‎7‎/‎9‎/‎2018 at 6:42 AM, motomattx said:

How about putting a volt meter on the output of the knock sensor to see if its actually putting out voltage and if you see it spike at all when your doing a pull?

I'm no expert on how the ecu, knock sensor is interfaced/works mate but if it's not putting out a voltage how would I be able to log it as I have?

 

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17 minutes ago, Rob W said:

I'm no expert on how the ecu, knock sensor is interfaced/works mate but if it's not putting out a voltage how would I be able to log it as I have?

 

I think I would ignore that comment, a typical voltmeter isnt going to be fast enough to see a 1ms voltage spike.  Have you tried the 100Hz log yet?

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Not yet Adam. Probably tomorrow. We did a lot of logging last weekend with some ears on it with nothing audible.

It seems to be happening so quickly I can't even hear it, maybe why the logging isn't picking it up. When it did knock on a separate occasion, I was able to hear a crack even as the system took over and pulled timing.

I'm going to pull the spark plugs today and have a look at them. And I'll get some logging done at 100Hz to the ecu and see what that says and report back.

How do I look open log files out of the ecu?

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Looking at one of your screenshots above it looks like you might be using an old version of PC Link?  Make sure your ECU is running 5.6.5 firmware, there were big improvements made to knock control in 5.6.4 & 5.6.5.

20 minutes ago, Rob W said:

How do I look open log files out of the ecu?

>logging>ecu log file download

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2 minutes ago, Adamw said:

Looking at one of your screenshots above it looks like you might be using an old version of PC Link?  Make sure your ECU is running 5.6.5 firmware, there were big improvements made to knock control in 5.6.4 & 5.6.5.

>logging>ecu log file download

Thanks Adam. Last time I updated the firmware I had some issues with the tune so I went back to this version. Will the compare function show me what changes. Eg - The TPS needed to be reset.

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It would be nice if these base tables could self populate whilst performing a known "safe" run to fill in the base tables with a background noise level. Then simply add the 10-20% to those values

the table could average over a few pulls if need be.

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On ‎7‎/‎15‎/‎2018 at 7:30 AM, Stevieturbo said:

It would be nice if these base tables could self populate whilst performing a known "safe" run to fill in the base tables with a background noise level. Then simply add the 10-20% to those values

the table could average over a few pulls if need be.

That would be awesome Steve.

My problem is at the moment is I can't get a known safe run with these little spikes of timing coming out.

I pulled the plugs on the weekend and no signs of any det. I didn't get a chance to get the car out but I'll log it to the ecu and report back as soon as I can.

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