Tonight under hard acceleration my engine started knocking. I had just put in some STP gas system treatment, so I don't know if that had anything to do with it. I'm running the Predator 87 tune with 87 octane Gulf gas. I put the stock tune back in and the problem went away.

I guess my question is, if this happens again. How do I adjust my tune to stop the knocking? Do I adjust the spark? Which way? What else?

Thanks.

 

Yeah it makes sense the mix would lean the gas out. Next time I'll know better and put in some 93.

 

It depends at what RPM range the engine is knocking under acceleration. Mine was doing it just above 4k so I retarded the timing by 2% in the 4k-7k range. Problem solved. I'm currently running the canned C&L predator tune for 93 octane.

 

ok that makes sense. I think it was in the 4-7 range as well. I may be a retard, but retard means go -2%?

 

Lucas Fuel Conditioner and Injector Cleaner.

-Dan

 

Yep, you will have an option to advance or retard the timing with the tuner. Try -1% first and if it is still knocking a little go to -2%. You shouldn't (and I wouldn't) have to go any less than that.

Fuel additives and all of that are typically with older cars with dirty injectors. Don't waste your time or money with that stuff for now.

 

Hey Dustin... I may be telling you something you already know.... but I'm retarded too, so don't take offense. What the "knock" or "ping" is is your fuel mixture exploding before the piston is TDC... Since the higher octane fuels are more stable, you can advance the ignition to spark sooner so that you get better power out of your stroke than if the mixture were to explode after TDC when the piston is already on the way down... Bla, bla bla... I'm sure you already know that... but yeah, when the octane level is decreased, and the mix less stable, so then it will explode by compression, instead of waiting for ignition... the same principle that a diesel runs on. But, yeah... the mixture explodes while the piston is still traveling upward, thus the damage that it has the potential to cause. But, yeah... just to help you understand which direction to tune your spark. And if you already knew that... perhaps someone that didn't is reading this.