Greaseymec

iTrader: (9)

New to the tuning game. Got a question about spark retard. I ran a log on a pass I made at the track. (used datamaster) I noticed a 9 deg spark retard at launch with a increase in knock count. (think it might be my new exhaust setup baging on the bottom of the car) As the run progressed the spark retard decreased to 4 deg. but I had no increase in knock count for the rest of the run. My question is why would I get spark retard without an increase in knock count? 93 octane gas. KPA at 98 with 34 deg. of timing above 4K rpm. O2 mv 890s on both sides. Any guesses?

Mec

brad8266

iTrader: (23)

890 on the O2 is lean. Start by fixing that. And 34 degrees at WOT is way to much, bring it down to around 27 and try that.

pdanrichey

iTrader: (4)

34 deg of timing over 4k rpms seems very high to me. I think I'm runing mid to low 30s till about 3500rpms, then mine drops to the mid 20s on 93 octane. You need to either add more fuel in the areas where you're getting knock, or retard your timing there until it goes away.

Greaseymec

iTrader: (9)

Please keep in mind that this is a LT1. I've seen a few tunes at or above 40 deg between 95 & 100 KPA above 4000 rpm. From what I've read, the LS1 does not require as much timing because of the better head design. If I have been miss-informed please set me straight. Just kinda wondering why I had the spark retard with no knock count increase. False knock maybe? Also the defination below was taken from DataMaster.

"o2 Volts

This is the measured voltage (in Millivolts) generated by the O2 (Oxygen) sensor. Will typically range from 100 mV (lean) to 900 mV(rich). For SFI systems, this is divided into left and right side values."

Please inform the uninformed. Thanks for the inpuit. Keep it coming!

Mec

brad8266

iTrader: (23)

Maybe the LT1 O2 sensors are different, as well as the timing. It could very well be false knock too.

ZL1Killa

iTrader: (17)

02 sensors are 02 sensors.. 100mv is rich and 900mv is lean.

add some fuel and try 30 degrees of spark

brad8266

iTrader: (23)

yeah i know that but the ls1 sensors go well past 900Mv on the rich side. Mine read like 1050 at WOT.