LS1 228R Tuning. Help me isolate this KNOCK

[wcw5023]

So I recently finished swapping a 128k mile LS1/T56 into my NA Miata. In the process, I upgraded the following:

-'99 LS1, stock untouched 853 heads
-228R .600/.600 112 LSA cam
-PAC Beehive springs
-7.425" Pushrods
-LS6 Intake
-New timing sprockets/LS2 Chain
-ASP 25% Underdrive
-MSD Wires
-TR55 Plugs
-Sanderson Shorty 1.50" Primary Headers
-True Dual 2.5" Exhaust/catless

Please see the attached logs/tune.

I am currently working on dialing in my VE tables, so running Open Loop, MAF-less. and a bunch of tables zero'd out. Commanded timing is matching spark tables, so no concern there. Again, keep in mind, I am still trying to dial in VE's.

My concern is, It seems like this isnt much timing at all to be running to get this degree of knock. Its not a very repeatable condition, I get it on some logs but not all. Of course, im trying to do a cross-comparison, but as many of you may know, that is difficult with so many variables.

My next course of action, is to go out and see if I can locate some 100+ octane to try.

Also note that I am running poly engine mounts, and stock transmission mount. It is, by no definition of the word, harsh in that department. Stock 243 head, which have never been off.

[IARLLC]

How did the back of the valves look when you had the intake off? Just curious if it may have a carbon build-up on the pistons. It might be worth it run a can of Seafoam through the intake. Just a thought.

I would definitely agree that the ignition advance is not too aggressive. The KR that is showing up does correspond with heavier throttle application. It is probably a tight fit in there. Is the exhaust close to anything (above it on the driver's side or below it on the passenger side) so that when you get on it there is contact? You are running around 190 coolant temp. A lot of guys like to run the LS1 quite a bit cooler but I doubt that is the issue with yours.

At the beginning of the run the wb was showing about .5-1% leaner than commanded but whenever you get into the gas it looks rich enough to not blame the air-fuel ratio for KR. Not sure what is causing it. Good luck.

[10SecSleeper]

I've attached a tune with some adjustments made, Give that ago. If still knock, try removing 5 degrees from areas of knock and just before knock shows in log and see if it reduces or goes away in logs. If it does, then you likely have real knock.

It could be caused by poor quality fuel.

ITS_WORKING_428_New.hpt

[wcw5023]

How did the back of the valves look when you had the intake off? Just curious if it may have a carbon build-up on the pistons. It might be worth it run a can of Seafoam through the intake. Just a thought.

I would definitely agree that the ignition advance is not too aggressive. The KR that is showing up does correspond with heavier throttle application. It is probably a tight fit in there. Is the exhaust close to anything (above it on the driver's side or below it on the passenger side) so that when you get on it there is contact? You are running around 190 coolant temp. A lot of guys like to run the LS1 quite a bit cooler but I doubt that is the issue with yours.

At the beginning of the run the wb was showing about .5-1% leaner than commanded but whenever you get into the gas it looks rich enough to not blame the air-fuel ratio for KR. Not sure what is causing it. Good luck.

Thanks for taking a look! Back of the valves looked pretty good when I had the intake off, did my best to clean them up but didnt go too crazy on them. But, it is a 128k mile engine, so I will definitely try the seafoam. Ive had pretty good luck with it in the past.

As far as contact, I poked around for a bit to look for signs, but didnt come up with much. The passenger side exhaust runs pretty close to the floor in one location, but its about 1.5 feet downstream of the collector, and the underside of the car is lined with isulation mat ( thermo-tec cool-it ) , so even if it did hit there, it shouldnt cause any kind of metallic reverberation. But I will definitly go over everything one more time.

Thanks for confirming the my AFR's and timing arent really in the "knocking" range. Makes me feel a little less crazy haha.

[wcw5023]

I've attached a tune with some adjustments made, Give that ago. If still knock, try removing 5 degrees from areas of knock and just before knock shows in log and see if it reduces or goes away in logs. If it does, then you likely have real knock.

It could be caused by poor quality fuel.

ITS_WORKING_428_New.hpt

Thanks so much! Ill skim that over and see if the weather will permit me to give it a shot later! Ill let you know how it goes.

[10SecSleeper]

I've tuned many car's with similar combos. Every once in a while I come across one that can't handle much over 20 - 22 degrees at peak torque.

[wcw5023]

I've tuned many car's with similar combos. Every once in a while I come across one that can't handle much over 20 - 22 degrees at peak torque.

I appreciate your insight. If its not too much trouble, would you mind enlightening me on some of the changes you made to my tune?

I noticed several differences:

- BKR Tables
- Changed to (2) across the board. I am a little confused as to the purpose of this, I would understand playing the the "Enable Delta" seeing as its a swapped car, but not sure how lessening the values would do much for me. I know of some people zero-ing out the table to eliminate the BKR, but im not entirely comfortable doing that either.

- PE Enable
- I see you re-enabled PE, are you just trying to verify knock isnt due to AFR? As I mentioned, I had this disabled to fine tune VE tables. And one I had them fairly dialed, I planned on re-enabling anyways. Just curious as to your methodology here to isolate this knock.

Again, I really appreciate it ! Just trying to become more fluent in HPTuners!

[Nastruck]

As far as the PE vs tuning the VE table it will not throw off your tuning. I wouldn't disable PE just to tune the VE. As long as your logging AFR error into your scanner the VE will still follow the same flow pattern no matter what your PE command is. Running no PE and running stoich wide open throttle can produce knock from being too lean.

[wcw5023]

As far as the PE vs tuning the VE table it will not throw off your tuning. I wouldn't disable PE just to tune the VE. As long as your logging AFR error into your scanner the VE will still follow the same flow pattern no matter what your PE command is. Running no PE and running stoich wide open throttle can produce knock from being too lean.

Thank you for the input. That makes sense. I disabled it only because I was trying to hit certain load cells that would sometimes trigger PE when I didnt want it to. I am not targeting stoich at WOT even with PE disabled. But I appreciate the concern!

[Nastruck]

so what are you targeting other than stoich and what are you attempting to do with your way of tuning?

[dermotw]

Re: Burst Knock Retard, just in case you don't know, its an attempt by GM to anticipate knock - so its not triggered by the knock sensors, but by fast throttle transitions, and it will retard the timing if it sees any. In a tuned car, and one where (hopefully) we are setup ok, its more or less irrelevant, which is why people often just turn it off. In a light car, also less relevant..

You can log it anyway...

-D

[wcw5023]

Re: Burst Knock Retard, just in case you don't know, its an attempt by GM to anticipate knock - so its not triggered by the knock sensors, but by fast throttle transitions, and it will retard the timing if it sees any. In a tuned car, and one where (hopefully) we are setup ok, its more or less irrelevant, which is why people often just turn it off. In a light car, also less relevant..

You can log it anyway...

-D

Thank you! Am I correct in assuming that in Open Loop, and running MAF disabled, that I should not be triggering BKR anyways? I guess it could use IAT's and MAP to calculate the cylinder mass delta. But that would surprise me!

[dermotw]

I think it still works in OL... easy to recognise anyway, since it only happens at a throttle transition.. In a light car with good setup, I wouldn't expect it to trigger ever, really. Mine does not, although wayyy back in the tuning process I recall that it did sometimes, before I got it reasonably set up.

EDIT: BTW your MAP Kpa seems a bit low on full throttle, usually it would be 98/99, yours is 94 - maybe the air path is not too wonderful?

[wcw5023]

I think it still works in OL... easy to recognise anyway, since it only happens at a throttle transition.. In a light car with good setup, I wouldn't expect it to trigger ever, really. Mine does not, although wayyy back in the tuning process I recall that it did sometimes, before I got it reasonably set up.

EDIT: BTW your MAP Kpa seems a bit low on full throttle, usually it would be 98/99, yours is 94 - maybe the air path is not too wonderful?

The intake path should be wide open, If theres a restriction, Its probably the exhaust, 1.5" primaries.. Just a guess though, Depending on the weather , Ive seen 98-ish. Im also in Akron OH, so around 1,100ft.

[wcw5023]

I've tuned many car's with similar combos. Every once in a while I come across one that can't handle much over 20 - 22 degrees at peak torque.

So I went out and logged today. Ill attach the results. I transfered your mods over to my tune, since it was having some sort of issue writing your file.

Knock is decreased, but still present. I ran a can of seafoam through it this morning, drove around for about a half hour, then logged after that.

Whats interesting is the part throttle knock around 15:52..... Its making me suspicious of some sort of resonance issue. But that wouldnt make sense as to why the knock has decreased with these changes. The car is also feeling way way down on power at this timing advance table.

EDIT: also note that ambient air temps were a solid 15?+ higher than last logs. I will have to wait til weather cools down again to re-log to ensure this is not the reason for decreased knock,

[IARLLC]

Quick note: When I expect that pistons have a carbon build-up I usually get the engine nice and warm then run the Seafoam through a vacuum port for a while with a bit of RPM then gradually decrease RPM and increase Seafoam until it either dies or and am totally pouring it in at which point I have somebody shut it off getting the hot pistons as wet as possible with the Seafoam. After about a half-hour I fire it up and watch the smoke show. Maybe you already did all of that.

With it losing power with less timing I am more inclined to think it is really BKR.

[10SecSleeper]

We commanded it a little richer at peak torque, and also took away 1 - 2 degrees at peak torque and knock was reduced. Where do you buy your gas? Around me, if someone buys gas at QuikTrip expecting a tune. They will get knock at peak torque over and over. Unless you go 15 - 20 degrees in that area.

Then with a new tank of fuel from a place like BP. They have no knock and get away with 24 - 25 at peak torque with no issue.

Generally knock will occur at peak torque which happens around 4000 - 5000 rpms. All your knock appears to be in that area.

[wcw5023]

Quick note: When I expect that pistons have a carbon build-up I usually get the engine nice and warm then run the Seafoam through a vacuum port for a while with a bit of RPM then gradually decrease RPM and increase Seafoam until it either dies or and am totally pouring it in at which point I have somebody shut it off getting the hot pistons as wet as possible with the Seafoam. After about a half-hour I fire it up and watch the smoke show. Maybe you already did all of that.

With it losing power with less timing I am more inclined to think it is really BKR.

I went through a whole can of the "seafoam spray", and honestly didnt get a ton of smoke from it ,I expect everything is pretty clean to be honest.

As far as the BKR, when I uploaded this tune, I added to my config to monitor BKR and nothing is registered when I am experiencing the knock retard. So I dont believe that is the culprit.

[wcw5023]

We commanded it a little richer at peak torque, and also took away 1 - 2 degrees at peak torque and knock was reduced. Where do you buy your gas? Around me, if someone buys gas at QuikTrip expecting a tune. They will get knock at peak torque over and over. Unless you go 15 - 20 degrees in that area.

Then with a new tank of fuel from a place like BP. They have no knock and get away with 24 - 25 at peak torque with no issue.

Generally knock will occur at peak torque which happens around 4000 - 5000 rpms. All your knock appears to be in that area.

I will be sure to locate some fresh gas, I fill up at the same place every time. using only 93 in all my cars, but theres a BP across the street. So i will definitely try that next. Tried to find some 100+ octane today with no luck..

Side note: I DO NOT trust that "octane booster" crap they sell at the parts stores haha.

[wcw5023]

I noticed something else interesting today while analyzing my most recent log I uploaded.

As I mentioned before, I added "BKR" to the config file to monitor. If you scroll through the histogram, you see several instances of knock, but nothing registering under the bust knock retard. However, if you export the raw data to excel, and you scroll down to the ~420.2 second market, there is an instance where the BKR column registers a "2". and then regular knock triggers shortly after.

This doesnt occur before any other instances of knock, but I thought it was interesting none-the-less.... Waiting for better weather before going out any trying some different gas.