A Quick Tip (sorta quick, kinda long)

[Formz]

When tuning your car, if you have an AFC or other fuel controller, go as lean as possible before you get knock. I was just tuning my car, and was getting zero knock whatsoever, but the problem was, it didn't feel as fast as it should be. So I leaned it out a little bit, and sure enough I was running way too rich. However, do NOT go from really lean and richen things up from there. Because that's a good way to blow you're motor. It's always better to run a little rich then REALLY lean

Btw, dissregaurd your O2 values. They are worthless. Too many DSMers are concerned with o2 values, and I'm telling you they don't mean squat. I was just helping two 4 different people tune their cars. And these are cars that are in the 14s, the 13s, the 12's, and one in the 11's.

Car one: 14 second car, getting 13 counts of knock at .88 volts (1g). Which is a "relatively safe" area according to everyone running 93 pump on 1g's. Well, it was too much knock above 5k rpm. I richened it up 2% across the board, knock went down to 5. Richened it a tiny bit more, and got knock to zero at .9 volts. Which is considered rich for a 1g.
Car two: 13 second car, horribly tuned, getting 34 counts of knock and retarding timing to 6 degrees. Has no fuel control and massive boost pike. However, his o2's are reading anywhere from .90 (rich) to .80 (lean).
Car three, 12 second car, lots of tuning, car is running mint. almost 20 psi on the street and everything looks good. .86 volts, zero knock.
Car 4 was an 11 second 3kgt so I wont go into values for him because it really isnt the same.

So again, DONT rely on your o2 sensor. It is worthless.

 

[MitsuE95GST]

Hey Formz your right about the 02s for the most part. However it is a good tool to you when tuning your closed loop area. Many people don't have the money when they first start out to buy and EGT or pocket logger so they get a 30$ autometer 02 meter or something similar. It is a good thing to have one though, 02 sensors from car to car can very by a lot. But they are consistant on the same car. If someone has a PocketLogger and they do a pull from 2000-6000 they mite see that at 3000RPM they get 0 knock, 15* of advance, and a 02 of .88 well when they get up to 5500 they see that knock is at 25, there advance is at 9*, and there 02 is at .80. What does that mean? It means that they should richen the 5500 area up to around .88 because that is where it is'nt seeing knock. Of corse if they see these numbers from someone else with similar mods it does'nt mean that it will work for them. However I agree with you in the fact that it is'nt a wise thing to do to base your tuning soley on 02s but its a good thing to have.

 

[Formz]

ok so I guess we can broaden this and say, don't use your o2 values against some one elses. Because just because one person is at .86 and happy, doesn't mean you can tune it to .86.