[Atomic Ed]

Gents,

I'm really a neophyte when it comes to tuning, but I'm learning little by little. My next door neighbor and I were talking about tuning this weekend and the subject came up about false knock. On my old Gen 4 F body one would simply swap out the knock sensors from a corvette and call it good. Not the best approach, but at least the engine didn't come apart.

If someone has the time and inclination, would you give me (us) a quick lesson on how to go about separating out real knock from false knock? I'm wondering how much false knock is created from certain add-ons, such as a S/C or headers.

[EFI Tuning]

Ed,

There are a couple of paths to follow to help differentiate real knock from false knock. If you are tuning a high dollar build I would even go so far as investing in option #3.

1. Reduce the spark advance in the offending area of the spark table and see if it has a measurable impact on the knock retard. If the KR reduces as you reduce the spark advance it is real and needs to be corrected for.

2. If still in doubt add some high octane fuel to the tank and raise the octane considerably. If the KR is absolutely the same after doing 1, 2, or a combination of 1 and 2 then you are highly likely dealing with false knock. This will need to be corrected for in the knock threshold tables (only as much correction is absolutely necessary. You don't want to go numb to real events).

3. Install a Plex unit and tune with that. The nice part about something like the Plex unit is that it will measure the noise floor of your specific engine. I will be investing one of these at some point.

Tim

[Atomic Ed]

Thanks Tim!

I learned something today.