wrd1972

Is it possible to de-sensitize the knock retard system with a custom tune.
I though I once read that Ion can do this with his custom tune.

I may have just a tad of KR from the headers and RR's.
Thanks

RamAir95TA

Before you go looking into this problem, why don't you make sure you have a problem first? Get a scanner on it.

teke184

install an lt4 knock module...

do a search...don't know the price or PN off hand

wrd1972

I will be getting a Scanmaster.
Im just want to understand how to correct the problem ahead of time.

Dave '97 Z28 M6

As already suggested, the first order of business is to verify that you actually have KR. I use TTS Datamaster on a laptop with an AKM cable.

If KR shows up on the scan/datalog, you have to determine if it's real knock or "false" knock. Run some high-octane gas (use an octane booster) in the car... if it shows KR with 100 octane gas, you can be sure that it's false knock. If the KR disappears with the 100 octane, it's probably real knock occuring with the lower octane gas.

At this point, if you're sure the knock is not "real", you have several options:
- bypass the knock sensor with a resistor
- zero-out the "burst retard" table in the PCM
- reprogram the PCM to allow for a bit of knock before retarding timing
- totally remove KR from the PCM

Naturally, it is preferred to not completely remove the PCM's ability to detect knock, and protect the engine from low-octane gas, etc.

RamAir95TA

I agree with everything you said, minus the use of octane booster. They only raise the octane by tenths of a point. His best bet is to run a gallon or so of100-octane straight.

wrd1972

Can this test be done with the engine simply idleing or do you have to actually drive it.

Dave '97 Z28 M6

Thanks for the correction - I've never actually used the stuff myself.
You're going to have to drive the car, with a scanner/laptop hooked up, logging or monitoring the KR. You'll need to do a couple of full-throttle pulls through the full rev range (I do it in 3rd gear, from 1500-6500).

speed_demon24

Whats burst knock retard? I'm trying to solve my KR issues too...

OBE1 95Z28

Be sure to include shifting points in your log data. Common to get some knock during shifting.

Dave '97 Z28 M6

It's the KR that the computer dials in for a fraction of a second when it detects a sudden change in MAP, i.e. when you quickly open the throttle.

I'm not sure how much of an effect this has on normal KR, though.

speed_demon24

It doesn't keep getting KR if from burst does it? For example, yesterday, my car was running fine, then I decided to hit it in 2nd from 40mph, and I instantly got 5.0 degrees when I hit the gas, and it stayed at 5.0 degrees exactly the whole time I was at WOT..

Dave '97 Z28 M6

That's not burst retard. Like I said, though, I'm not sure if burst retard would make the PCM more prone to standard knock retard or not. I'm not even sure if "burst knock retard" is the correct term. I think the PCM can retard the advance for a fraction of a second upon a sudden large MAP reading change, i.e. when you snap the throttle open; and it will do this irregardless of input from the knock sensor/module. After that fraction of a second, the PCM will then base it's retard (if any) on readings from the KS/KM.

Hopefully someone with more knowledge will chime in.