Knock Retard questions / concerns

[TragicMike]

I'm reading up to 8 deg Knock Retard on what I believe would be considered Tip-In.

When going from light or off throttle to around 20% increase it registers almost every time,
and it seems to stumble a little on takeoff.

0204 Knock AVG.JPG0204 knock max.JPG

I just noticed this recently, but it may have been doing it for a while.
Tried running on low octane table and reducing even further, but it didn't seem to help.

Current tune as follows.
114- share.hpt
ETC Tip-in disabled
DFCO disabled

Is this likely a case of VVE airmass and MAF airmass not agreeing with each other, or should I be worried?

Log captures from last 40 minute run

0204 FT.JPG0204 VVE.JPG0204 MAF.JPG0204 VVE graph.JPG0204 maf Graph.JPG

[TragicMike]

Did this on purpose as an example:

EQ shows lean as well on the highlighted hump.

example.JPG

[blindsquirrel]

Since the KR PID only shows the timing being removed, and not the actual KS activity, there's no way to tell if KR is from actual knock being detected or the dumb predicted Burst Knock and there's no actual knock happening, it just thinks it might be about to happen.

Disable Burst Knock. [ECM[ 12765, set entire table to '0'.

[Cringer]

You can log the PID [Burst Knock] to see if that it what is causing it, I am pretty sure that is what is going on.

Burst knock removes timing "just in case" during throttle transients to prevent knock before it might actually happen. In your screenshot it shows several KR events and they are all maxed out at 4* which is very convenient.

If you do disable Burst Knock, I would suggest changing the value for [ECM] 2740 - Knock Retard Disable Time to 0. This will ensure that if real knock is happening, it will be pulled immediately without having to wait (simply zeroing out Burst Knock will disable the effect, but it will still be "active").

Edit: Also your MAF table needs work.

[blindsquirrel]

Burst Knock is there because the factory tune is dogshit with power enrich essentially disabled which promotes tip-in knock, and yours pretty much is still disabled. Give it fuel when it needs it!

Min MAP: somewhere between 70-80 kPa, depends on cam/idle vacuum/altitude
Get rid of all the stupid Delays
Enrichment Ramp In: 1.000

[TragicMike]

Much better.

I'm still dialing in the MAF/VVE as well, but this is after disabling Burst Knock
Any idea where the rest of that is coming from?

118 max kr.JPG



I haven't been in any hurry to enable PE mode, but I'm about ready to get into that.

[TragicMike]

After a think I understand what you mean about giving fuel when needed.

I removed the PE timer and set ramp in.

Min map set to 70 as that is above my normal idle.

Thank you.

@Cringer are you referring to the hump/divot at the low end of the MAF curve? I can't get any data in that range right now. I will make an attempt to interpolate it soon.

[Cringer]

After a think I understand what you mean about giving fuel when needed.

I removed the PE timer and set ramp in.

Min map set to 70 as that is above my normal idle.

Thank you.

@Cringer are you referring to the hump/divot at the low end of the MAF curve? I can't get any data in that range right now. I will make an attempt to interpolate it soon.

Yes but also DynAir and VVE are right around 22 g/s and MAF is 44 g/s.

[TragicMike]

That was right at the 20% throttle stomp.

It caught up eventually, but the timing pull didn't help anything.

Seems to be much better now after turning off the Burst and adjusting VVE/MAF more.

[Allen Vos]

I'm reading up to 8 deg Knock Retard on what I believe would be considered Tip-In.

When going from light or off throttle to around 20% increase it registers almost every time,
and it seems to stumble a little on takeoff.

0204 Knock AVG.JPG0204 knock max.JPG

I just noticed this recently, but it may have been doing it for a while.
Tried running on low octane table and reducing even further, but it didn't seem to help.

Current tune as follows.
114- share.hpt
ETC Tip-in disabled
DFCO disabled

Is this likely a case of VVE airmass and MAF airmass not agreeing with each other, or should I be worried?

Log captures from last 40 minute run

0204 FT.JPG0204 VVE.JPG0204 MAF.JPG0204 VVE graph.JPG0204 maf Graph.JPG

Good to know about the knock burst but for what its worth when my VVE was out to lunch and didn't match with the MAF I had big time hesitation and stumbles of idle.

Matched it up properly and hesitation was gone

[Allen Vos]

You can log the PID [Burst Knock] to see if that it what is causing it, I am pretty sure that is what is going on.

Burst knock removes timing "just in case" during throttle transients to prevent knock before it might actually happen. In your screenshot it shows several KR events and they are all maxed out at 4* which is very convenient.

If you do disable Burst Knock, I would suggest changing the value for [ECM] 2740 - Knock Retard Disable Time to 0. This will ensure that if real knock is happening, it will be pulled immediately without having to wait (simply zeroing out Burst Knock will disable the effect, but it will still be "active").

Edit: Also your MAF table needs work.

Is disabling the "Burst Knock" as simple as Maxing out the Burst knock delay?

My delay is set to "0" from the factory

[Allen Vos]

Burst Knock is there because the factory tune is dogshit with power enrich essentially disabled which promotes tip-in knock, and yours pretty much is still disabled. Give it fuel when it needs it!

Min MAP: somewhere between 70-80 kPa, depends on cam/idle vacuum/altitude
Get rid of all the stupid Delays
Enrichment Ramp In: 1.000

So does "min map" get set to whatever vacuum or KPA your engine is idling at if your have done a cam swap?

[07GTS]

min map is based on the engines load point u want to allow it to enter pe with the enable of the other settings also TPS, n/a 70-80kpa is a point of load where u want to richen it to help keep temps good and make power, below that u can be in CL just fine

[Allen Vos]

min map is based on the engines load point u want to allow it to enter pe with the enable of the other settings also TPS, n/a 70-80kpa is a point of load where u want to richen it to help keep temps good and make power, below that u can be in CL just fine

OK that makes more sense now that you explained it that way.

I was just wondering as my car with the cam I have idles at 57 KPA so thats not to far off 70 KPA

It kind of closes in and makes it a lot narrower range at 57 KPA vs the 30 or so KPA the car was at stock

[07GTS]

camshafts will do that but soon as u use the throttle it will drop lower and then go higher again when actual load is applied when driving, as long as u can drive normally without going into PE thats good then when u use decent throttle u want to enter pe so the 70-80kpa range is good, will have to wait till u can drive it to go further there

[Cringer]

Is disabling the "Burst Knock" as simple as Maxing out the Burst knock delay?

My delay is set to "0" from the factory

No. Disabling burst knock is zeroing out the [ECM] 12765 - Burst Knock Retard vs. Cylair Delta table.

The delay is telling the ECM if you want to allow burst knock and real knock to be activated at the same time or not.

0 means do not wait on burst knock if it is already active, let's pulling timing immediately since the knock sensors are active.
A value larger than 0 means to wait this many crank pulses while burst knock is active before attempting to pull timing while the knock sensors are active.

But if you make the Burst KR table all zeros, that doesn't disable Burst KR. It just means that it will actively remove 0* of timing. There are no rules to disable it by ECT, RPM, MAP values etc like there are in other systems in the tune. So Burst KR is always active. We just prevent it from pulling any timing...hence the delay should be zero to always allow the knock sensors to pulling timing ASAP without interference. It is a difference of disabling something vs having it do nothing when called upon.

[Allen Vos]

No. Disabling burst knock is zeroing out the [ECM] 12765 - Burst Knock Retard vs. Cylair Delta table.

The delay is telling the ECM if you want to allow burst knock and real knock to be activated at the same time or not.

0 means do not wait on burst knock if it is already active, let's pulling timing immediately since the knock sensors are active.
A value larger than 0 means to wait this many crank pulses while burst knock is active before attempting to pull timing while the knock sensors are active.

But if you make the Burst KR table all zeros, that doesn't disable Burst KR. It just means that it will actively remove 0* of timing. There are no rules to disable it by ECT, RPM, MAP values etc like there are in other systems in the tune. So Burst KR is always active. We just prevent it from pulling any timing...hence the delay should be zero to always allow the knock sensors to pulling timing ASAP without interference. It is a difference of disabling something vs having it do nothing when called upon.

Thank you for clearing that up man, I would be lost without half you guys lol

Makes perfect sense now lol

[TragicMike]

Love the new videos Cringer.

https://www.youtube.com/watch?v=GUzHgLQbOGc
https://www.youtube.com/watch?v=c7rzX6DZPqY