Twin Turbo 16 Camaro WOT Knock Retard

[WongBob]

Doing a 16 Camaro with a rear mount twin setup. Its completely stock other than the turbo setup, LS9 map sensor, and a drag radial. I have had to do some odd things with it to make the setup work due to erratic MAF readings. I have the MAF low fail set to 4000hz so it reverts to SD for idle and light part throttle. I am using the MAF for everything over 4000hz. All of that is working good and as I had hoped. I have the VVE dialed in pretty good. Enough so that the car drives like stock in SD and with the blend.

The problem I am having is at WOT I am getting KR in boost. I have searched the forum and tried every suggestion I could find to no avail. I have added timing, limited max retard, leaned it out, increased and decreased SOI/EOI. I have the wot cam angle zeroed. No matter what as soon as boost comes in the KR goes right to the max allowed retard and holds there. Anyone have any suggestions?

[WongBob]

I feel like I should also note that it pulls the exact same timing on 4psi as 10psi. Running on wastegate springs.

[Jggregory99]

Why would you ADD timing if you are getting KR? I mean, Correct me if I'm wrong, but, If you are adding timing and KR Max is being reached then the KR is just pulling all the additional timing out. I would start by creating a histogram of KR vs Dynamic Cylinder Air (Math) to see exactly where the KR happens in the run and pull timing in that Kpa/RPM range until you get no knock and see where you stand. Then slowly add 1-2* till you reach the first consistent knock then back it off. JMO...

[Higgs Boson]

WOT cam angle zero'd means it is fully advanced. Put it back to stock if the cam is stock.

ReEnable the MAF (unfail it by using stock settings) and clear your codes and make another pull.

[WongBob]

Higgs, the maf is enabled above 4000hz. In the log you will see that wot runs between 8000hz and 11000hz. The car has a very turbulent maf reading and will not idle and control light part throttle on maf. If you look at the maf tavle you will see i have it flatlined down low in an attempt to make it idle. It worked perfectly, but light part throttle is no good with maf swings of up to 2000hz. My only choice was to fail the maf below 4000hz so that idle and light part throttle would rely solely on the VVE. That part of the tune is working perfectly. The problem is only in WOT and only in boost. At that point the maf is fully functional and pretty well dialed in for the dual nozzle meth setup.

Jg, after doing a lot of reading I found several posts by guys that I would trust and have a good track record for solid information stating that too low of timing coupled with too rich of a mixture can cause kr. I had a starting point of 10*. It was pulling 10* out in boost. I was simply thing to limit that low timing. If you will look at the attached files you will see that i am already logging all of those things. I know exactly when and where the knock is coming in. The problem is that i cant locate the source. It has been the same since i started.

[mcd_57]

Is your wideband confirming that you are reaching and maintaining the desired AFR? Are your knock sensitivity values stock?

[Higgs Boson]

Higgs, the maf is enabled above 4000hz. In the log you will see that wot runs between 8000hz and 11000hz. The car has a very turbulent maf reading and will not idle and control light part throttle on maf. If you look at the maf tavle you will see i have it flatlined down low in an attempt to make it idle. It worked perfectly, but light part throttle is no good with maf swings of up to 2000hz. My only choice was to fail the maf below 4000hz so that idle and light part throttle would rely solely on the VVE. That part of the tune is working perfectly. The problem is only in WOT and only in boost. At that point the maf is fully functional and pretty well dialed in for the dual nozzle meth setup.

Jg, after doing a lot of reading I found several posts by guys that I would trust and have a good track record for solid information stating that too low of timing coupled with too rich of a mixture can cause kr. I had a starting point of 10*. It was pulling 10* out in boost. I was simply thing to limit that low timing. If you will look at the attached files you will see that i am already logging all of those things. I know exactly when and where the knock is coming in. The problem is that i cant locate the source. It has been the same since i started.

All I am saying is to try it, you can always put it back how you have it. Don't forget to clear your codes.

you can also dump in some race gas to see if the knock goes away.

what knock pid are you using?

[schpenxel]

Can you enable/disable the MAF on the fly like that? I've never heard of anyone doing it like that but if it works that's pretty slick.

With MAF codes set to no error reported I'm surprised it works at all

[WongBob]

I am logging total knock retard and knock retard sae. Both match almost 100%.

The maf setup is working perfectly. I set the high and low to no error reported in hopes that it would just force sd and allow it to return to maf on the fly. It was a shot in the dark and it worked. I have tried it with the maf settings stock and the knock does the same thing. There are no codes currently set.

What really is confusing me is the fact that I get the same KR with 4psi and 10psi. Straight to max allowed. That is why I dont see race gas helping.

[Higgs Boson]

Can you enable/disable the MAF on the fly like that? I've never heard of anyone doing it like that but if it works that's pretty slick.

With MAF codes set to no error reported I'm surprised it works at all

This is my concern. I don't think it does work even though it seems like it. The E92 is going to do what it wants with errors set up even on purpose and we can't always see it in the scanner. I guess I will have to fire up the tuning laptop and look at the tune.

[Ben Charles]

Higgs wants you to try race gas to possibly rule out False knock.... its a great idea specially if you are getting the same KR on low and high boost..
If I feel up to it later I'll look at the tune

[Higgs Boson]

You want to run off VE but you can't unfail the MAF once it's failed back and forth. Your VE table is nothing (untuned) and even has negative numbers. Your cam is fully advanced at WOT, your SOI table is really messed up, put it back to stock, PE fueling is too lean, Torque Model is too "edited," and so on.

[Higgs Boson]

Maybe I am missing something as to this being VVE dialed in pretty good?

Capture.JPG

Capture1.jpg

[WongBob]

I will set the cam angles back to stock and make adjustments to the driver demand and SOI, SOI and EOI are 10% over stock from .72 and 3000 on at this time with no other changes so they cant be "really" messed up. At this point I am positively running SD below 4000hz and maf beyond that. I cant tell you why it is working, but it is. Try it for yourself. The I believe the issue is maf turbulence. If you look at the maf at any given point there are wild swings that are killing fueling and I believe that is causing a lot of the problem. I started with 1.22 enrichment rate and leaned it out some while testing to see if it was a possible fuel knock. I usually run 1.23 enrichment rate on boosted gen3 and gen4 motors and have had great success.

Also, as far as the VVE, something was definitely missed. Mine look nothing like that.

VVE2.PNG
VVE.PNG

[Higgs Boson]

I will set the cam angles back to stock and make adjustments to the driver demand and SOI, SOI and EOI are 10% over stock from .72 and 3000 on at this time with no other changes so they cant be "really" messed up. At this point I am positively running SD below 4000hz and maf beyond that. I cant tell you why it is working, but it is. Try it for yourself. The I believe the issue is maf turbulence. If you look at the maf at any given point there are wild swings that are killing fueling and I believe that is causing a lot of the problem. I started with 1.22 enrichment rate and leaned it out some while testing to see if it was a possible fuel knock. I usually run 1.23 enrichment rate on boosted gen3 and gen4 motors and have had great success.

Also, as far as the VVE, something was definitely missed. Mine look nothing like that.

VVE2.PNG
VVE.PNG

Why would you move SOI 10% over stock? Also, your torque model is more than just your DD table, also your Peak Torque Table, the Torque Model Max table you have set to 312kpa (why did you do that?), etc.

You can't adjust EOI on these cars, those tables are for EOI during split pulse injection, which is not active.

If you create an error, in this case the failed MAF under 4000Hz, the error doesn't just disappear when you get back over 4000 Hz, it is still there and the ECM is still going to "protect the motor." While you may be running SD, there is more to the story than that when there is an error detected in the E92 logic.

Again, run race fuel and see if the knock is still there. Put your MAF error criteria back to stock and clear your codes. Rule these two simple to verify items out and we can move on.

Another thing I noticed is those pics of the VE table only go up to .9 PR. How are you fueling the car (or allowing the torque model to reference an airflow) while you are in boost? Yes I know you think you are using the MAF, but.... The VVE table must be fully tuned for the E92 to run properly, remember this is a torque based PCM, not airflow based. The torque model controls everything and references the airflow model to see where it is with torque production and then controls throttle, spark, and fuel to hit targets.

What MAP sensor are you running?

[WongBob]

Why would you move SOI 10% over stock? Also, your torque model is more than just your DD table, also your Peak Torque Table, the Torque Model Max table you have set to 312kpa (why did you do that?), etc.


You can't adjust EOI on these cars, those tables are for EOI during split pulse injection, which is not active.

If you create an error, in this case the failed MAF under 4000Hz, the error doesn't just disappear when you get back over 4000 Hz, it is still there and the ECM is still going to "protect the motor." While you may be running SD, there is more to the story than that when there is an error detected in the E92 logic.

Again, run race fuel and see if the knock is still there. Put your MAF error criteria back to stock and clear your codes. Rule these two simple to verify items out and we can move on.

Another thing I noticed is those pics of the VE table only go up to .9 PR. How are you fueling the car (or allowing the torque model to reference an airflow) while you are in boost? Yes I know you think you are using the MAF, but.... The VVE table must be fully tuned for the E92 to run properly, remember this is a torque based PCM, not airflow based. The torque model controls everything and references the airflow model to see where it is with torque production and then controls throttle, spark, and fuel to hit targets.

What MAP sensor are you running?

It was recommended for me to add to the SOI in the WOT area as a starting point. As for the torque model, I changed that thinking it might have been part of the problem, it wasn't.

I have set EOI back to stock. Should have been obvious when the tab in the fuel section is clearly marked "disabled".

I'm sure you are right about the maf fail, but whats weird is that it never sets a 103. I have 101 and 102 set to "no error". It runs perfectly below 4000hz and responds to VVE changes in those regions. Also, above 4000hz it responds to maf changes. If it werent for that, I wouldnt be so adamant in saying that it does work.

At this point I can not go back full maf and restore the factory maf settings. If you look at the log you will see up to 2000hz swings at light part throttle and over 1000hz at idle. The way the turbo kit was built they put the maf right after a bend and where it increases in diameter from 3" up to 4". I have been trying to tune around this. The only way I can see getting around this is to go 100% SD.

I will edit the PR axis and try to go that route.

It is an ls9 map.

[Higgs Boson]

can't you just move the maf?

I am not saying you need to enable the MAF forever, I am just saying to enable it and replicate the conditions where you are having a spark issue and see if you still do. then you will know another thing.....and maybe if you need to relocate the maf to a more suitable location (which you probably should anyways).

[WongBob]

Still working with this one. Replaced plugs back to a stock plug at .025 which was a definite improvement over the NGK 6510's at .025. I also tried race gas with little to no change. The problem exists in SD and MAF. Logs are almost identical with the exception that when running MAF the idle and light part throttle fueling cant be lined out. Im starting to wonder if the meth kit is the cause of the problem. New files, maybe a fresh set of eyes will help.

[WongBob]

Tested with meth kit off. It was not a meth issue. I am able to make full, clean pulls at this point with the only issue being max KR. Ended up having to close the gap down to .015 and it cleaned right up.

I saw where Andy was having a similar issue on a C7 and just zeroed his max KR table, but never updated the thread after the fact. Has anyone else figured out what may be causing the KR? I havent been able to find any other threads that relate to this problem. The car pulls clean and has zero audible knock. At this point I do not feel like it is real knock.

[WongBob]

Desensitized the knock sensors slowly until the knock was gone. Its good to go with 13-15* more timing now than previous logs.