H-5-L

Aloha,
I spend most of my time driving in the low octane table.92 octane is all i get without using racegas(unleaded from the pump..100octane or octane boost).
At the track,i pull my PCM fuses,have the tank full of octane,and all is well until that tank runs out.With the high octane,WOT,i will get 28* timing across the rpms,in the low tables i get 19* to 22*.I know of quit a few c5 that behave like this,some owners don't even realize it.
My question (finally),is do the f-body guy's have the same issues?My buddy's 99 anniversary WS6 doesn't go thru this.Is there a difference in the programs,different knock sensors,or both?
Mahalo.....

SmokingWS6

iTrader: (1)

I've never had a problem with it switching to the low octane table, it causes an ses correct? Do you have a handheld tuner like a hypertech? A lot of times they will make the car run leaner at WOT thus causing excess detonation. If you have tuning software another option is to copy the high octane table to the low octane table. That way you won't lose timing if it keeps trying to switch tables on you, however you run the risk of hurting the motor if it detonates too much.

Another_User

Do you have a 98? My 98 does nothing but sit on the low-octane table. There things that I think may be contributing:
1) The knock learn MAP is too high. Yes...knock learn keeps the PCM from learning knock from too low MAP. However you have to take the engine right to where the 98s get most of their KR for knock learn to start giving some timing back. At least I think it works that way.
2) Our knock sensors are too sensitive.
3) Our timing is the most aggressive.

My car always rides the low-octane table. Even when it is riding the low octane table from 3700rpm to somewhere in the 4000rpms I will get full PE KR (4 degrees), no matter what my timing is. It did it before I did any of my below mods, and after changing my tensioner, intake cleaning, and all the rest of the mods. Our KR system is...pretty screwed up.

SmokingWS6

iTrader: (1)

Thats odd. I run very high timing(tuned). I get about .3 KR on a wot run with a few spikes form 1.5 to 1.9. and stays on the high table as far as I know. I've never heard any audiable knock. I'm assuming the .3 could easily be my exhaust due to the noise.

Another_User

Yeah...it detects knock when my engine gets loud...right around 3700ish. I have no idea why. It has done it for as long as I have had a tool to check it with, no matter how much timing I pull. I think it is harmonics. The only thing left that I can imagine replacing is my clutch...if an out-of-balance clutch could even cause that kind of problem.

H-5-L

Thanks for your guy's input.I have a 99,i never hear knock,but the scanner shows it,and the power drops way off,at the track it was exactly .5 second slower and a 4 mph drop,emmbarrassing....i never forgot my octane again.I am going to change to the revised ks sensors,but i am not optomistic,my buddy in Arizona,has a 97 with a 2004 LS6 he has the same exact problem,just lives with it,reset at the track etc...i know a few others too,they actually thought there cars were fine,( no audible knock),but after resetting the PCM and adding octane,they realized how there car should be pulling.
I will see what i can do with the Vinnci programmer after cam install,but that not until the last week of Nov....grrrrrr...I would consider copying over the low table,as long as the timing will still back off if there was knock.Not sure if the Vinnci can do that.LS1 edit tunners are few out here.
Mahalo again......

H-5-L

One theory i had was,maybe the inner valve spring coil is rubbing the outter coil sometimes,i will know when i tear it apart in Nov.Or belt rumble,but i can't see the sensors being that sensitive.Who knows though,i don't know any f-body guys with this problem,but maybe there is..

Another_User

Nah, I have been using stock springs, and then I upgraded to LS6 springs that are still single/beehive style. I have never header WOT knock on my car. Occasionally I have heard low RPM pinging if I give it a fair amount of gas.