Question about KR

[noesfacil]

After logging my 02-C5 with original OS for a few laps at racetrack using 100 octane fuel, I found that I am getting short KR spikes at aprox 4800 RPM. I am assuming that if there is KR there is definitely knock. The spikes are of very short duration. I lowered the spark timing in the high octane table and still get the very short KR spikes in my graphs. Is this something that is normal? If it is, at what point should I be concerned in terms of KR duration? If it is not normal, Is there anywhere else I should be looking (apart from the spark tables)?

Any light on this will be appreciated.

thanks

[Redline Motorsports]

First rule with tuning........never assume!

It is not impossible to have false knock at that rpm. What timing is being commanded and how much KR do you have? With 100 octane fuel you should be able to get rid of any detonation with stock timing values and light mods.

Need more info!

Howard

[joecar]

noesfacil, welcome and hi there. :cheers:


What is your AFR and timing at the point where you see KR...?

[noesfacil]

Thanks for the prompt responses.

Timing varies, for example timing advance is 27and KR of 4 in another instance Timing advance is 36 (the highest) and KR is 17.5. All of the events are of very short duration (fractions of a second) I don't have the WB sensor working yet so I don;t have Exact AFR.

tried to attach the file but the zip is 263k and the forum limit is 117k.

[noesfacil]

Just to clarify the OS is stock but the tune is not. Raced a whole year using the tune which was created by some tuner before I bought the car. But for the first time was able to log using EFI Live and was surprised to see the random KR.

[dc_justin]

Thanks for the prompt responses.

Timing varies, for example timing advance is 27and KR of 4 in another instance Timing advance is 36 (the highest) and KR is 17.5. All of the events are of very short duration (fractions of a second) I don't have the WB sensor working yet so I don;t have Exact AFR.

tried to attach the file but the zip is 263k and the forum limit is 117k.

I used to see what looked like random spikes of KR in the 15-20* range. Then took a closer look and saw that my other sensors would all show crazy readings at the time. Like ECT would go from 190* to -200* for a split second. Turned out it was just a glitch.

After doing a crank relearn, those spikes have almost entirely gone away. I don't know what the two have to do with each other, but if you're having spikes larger than 8*, I would look into the possibility of it being a glitch of some sort.

[noesfacil]

Thanks for the info. I will try to create and and post a smaller file with the spikes so others can see. It will have to wait till after the 30th of June when I can test the car again. I belive with the 100 octane that we are on the safe side but still would like to know why the spikes occur.

I guess the question is how much, if any, knock is acceptable in terms of engine safety? I know it causes the engine to retard timing to protect the engine so theoretically I lose power temporarily. Next question, if I'm using 100 octane fuel, is it possible the sensors are confusing some other noise with knock? Remember this is strictly a track racecar. If it is possible, is there a way to reduce the sensitivity of the sensors? Is it safe?

Thanks all

Jorge