L96 "Ghost Knock" and Supercharger?

[Matt_]

So i've been keeping up with @Chrismnj 's thread and have been thinking about a supercharger for my 2500 which has the L96 6.0L.

When Justin was tuning my truck we were having an issue with some knocking at WOT and we couldn't get rid of it; tried different gas stations, adjusted the tune, seafoam in case of carbon buildup, etc... just would't go away. I'm not a WOT kind of driver, the trucks for towing not racing, so I think he advanced the timing and we let it be (@BlackBearPerf can correct me if i'm wrong).

So fast forward to the supercharger research, I came across a thread at silveradosierra where a member was asking about supercharging an L96, and a member replied with:

There is a few on performance trucks but what I read is not promising. In two instances the guys pulled the blowers off the trucks and went back to stock... The E78 ecm seems to be the issue on both instances. It's a weird computer used only on the gas engine HD trucks and the Chevy Cruze. Doesnt have a ton of tuning support solely based on the applications. And honestly the turbo Cruze is boosted obviously but it's not like the OS on the trucks is the same lol.

Even mine is weird and has ghost knock on a wide open throttle launch off idle and I can't get rid of it. All the burst knock and whatnot is zeroed out but even changing timing or fuel does nothing. Kind of keeps me from installing the cam and headers I have as I dont want to deal with something that wont run properly.

If I can get the weirdness of the situation sorted I might move forward.. time will tell.

Soooo insert cold feet...

Would appreciate some advice/experience. I know of at least one FB group member who has a supercharger, might be the LY6 engine though (not sure if the ECM mentioned above applies). But even still, would the issue I had with knocking at WOT be an issue if I wanted to go with a supercharger/cam/etc upgrade?

 

[Chrismnj]

First of all good luck on your project if you decide to go with it. Personally I am learning a lot as I go along, and sure there will be a learning curve after all set and done. At this point I am leaning more towards valve train upgrade as well. Here is some guys that helped me on this build. @Tonyrodz @67RS427 @kbuskill , sorry if I have unintentionally missed anyone,

 

[kbuskill]

So i've been keeping up with @Chrismnj 's thread and have been thinking about a supercharger for my 2500 which has the L96 6.0L.

When Justin was tuning my truck we were having an issue with some knocking at WOT and we couldn't get rid of it; tried different gas stations, adjusted the tune, seafoam in case of carbon buildup, etc... just would't go away. I'm not a WOT kind of driver, the trucks for towing not racing, so I think he advanced the timing and we let it be (@BlackBearPerf can correct me if i'm wrong).

So fast forward to the supercharger research, I came across a thread at silveradosierra where a member was asking about supercharging an L96, and a member replied with:



Soooo insert cold feet...

Would appreciate some advice/experience. I know of at least one FB group member who has a supercharger, might be the LY6 engine though (not sure if the ECM mentioned above applies). But even still, would the issue I had with knocking at WOT be an issue if I wanted to go with a supercharger/cam/etc upgrade?

I have no experience with superchargers directly.

My guess is the answer to your question would depend on what the original knock sensor problem stems from.

Logic would dictate that if you have an existing knock problem that it will probably be exacerbated by adding boost.

 

[67RS427]

Is the motor actually knocking or is the ECU pulling timing because it thinks it's knocking? Can you actually hear it knock?

 

[Matt_]

Is the motor actually knocking or is the ECU pulling timing because it thinks it's knocking? Can you actually hear it knock?

I never actually heard it knocking.

Just went through my emails and he did pull some timing in the last tune update. Said it got better but still some light knocking under heavy throttle. We left it at that and I said I'd bump my gas up to 91 (vise 89) octane when towing.

But as suggested, this could probably be an issue if I try adding boost

 

[67RS427]

I never actually heard it knocking.

Just went through my emails and he did pull some timing in the last tune update. Said it got better but still some light knocking under heavy throttle. We left it at that and I said I'd bump my gas up to 91 (vise 89) octane when towing.

But as suggested, this could probably be an issue if I try adding boost

Could just be false knock... Those sensors are sensitive as F from the factory and can be tuned/desensitized with HP Tuners or EFI Live. I had to change the knock sensor settings on mine since my ECU thinks I have an aluminum block but I'm running iron now and sensors are in a different location on the block.

My suggestion is to turn off burst knock and add timing until you actually hear it knock, you won't need to go crazy and won't take much or hurt anything. Obviously get out of the throttle when you do and slowly desensitize the sensors until it only shows real audible knock. You can then turn burst knock back on which should also be desensitized.

*also, running 91 isn't a bad idea. I'm not sure where you live but in Michigan the winter gas sucks and I see a fuel economy drop just from that alone and it does affect timing too.

 

[Matt_]

Appreciate all the help and info!!

I'm in NJ but all the tuning was done this past summer/early fall.

 

[67RS427]

Appreciate all the help and info!!

I'm in NJ but all the tuning was done this past summer/early fall.

Could be a bad sensor I suppose as well... They are really cheap and easy to replace. Worth a shot... Mine was knocking on me today at WOT on a 2nd gear pull. It was enough to be audible but I'm not too worried with my forged rotating assembly. I'm gonna add a bit more fuel at that load and see if it goes away, if not, yank a degree or two of timing. Tuning is NEVER a one and done thing. It's a constant process to get something to run properly year round. It would be much easier if you learned how to read your own logs and had a better understanding of what is happening and when it happens. You can only fix it if you know the load and conditions while it happens, VERY VERY hard to do remotely just browsing over someones logs. I would not be yanking a bunch of timing for false knock though. Fix the sensor sensitivity so you can actually trust your knock sensors and the ECU to do its job.

 

[BlackBearPerf]

So i've been keeping up with @Chrismnj 's thread and have been thinking about a supercharger for my 2500 which has the L96 6.0L.

When Justin was tuning my truck we were having an issue with some knocking at WOT and we couldn't get rid of it; tried different gas stations, adjusted the tune, seafoam in case of carbon buildup, etc... just would't go away. I'm not a WOT kind of driver, the trucks for towing not racing, so I think he advanced the timing and we let it be (@BlackBearPerf can correct me if i'm wrong).

So fast forward to the supercharger research, I came across a thread at silveradosierra where a member was asking about supercharging an L96, and a member replied with:



Soooo insert cold feet...

Would appreciate some advice/experience. I know of at least one FB group member who has a supercharger, might be the LY6 engine though (not sure if the ECM mentioned above applies). But even still, would the issue I had with knocking at WOT be an issue if I wanted to go with a supercharger/cam/etc upgrade?

Hello Matt, Justin would be available via email only to help you diagnose anything with the tune, or to verify what was done with the tune. He would be more than happy to look at a data log, and update the tune as needed.

 

[Matt_]

Hello Matt, Justin would be available via email only to help you diagnose anything with the tune, or to verify what was done with the tune. He would be more than happy to look at a data log, and update the tune as needed.

Thanks! Just to clarify I'm extremely happy with my tune.

It's not worth spending time on now, but it seems like if I get serious about installing a supercharger I'll probably need to work with Justin to find and eliminate the WOT knock first.

I think a new motorcycle is sounding like a better idea this summer