I know every car likes different tuning but there must be a base tune to start with depending on the power produced by the modifications.
Yes, a base tune, but that will be set by the chip maker based on what mods your car has and what you tell him you want from the car.
Please correct me if I am wrong but when O2's are mentioned, it means that the sensor is telling the computer how much oxygen it is needed to correct the a/f ratio, right? The O2 sensor doesn't actually measure the oxygen present in the spent gases.
Kind of...The NB O2 simply measures oxygen content of spent exhaust gases and is expressed in .00-1.00 V, That is crudly compared to gasolines stoich which is 14.7 A/F ratio and would probably fall about .450mv on the O2's ouput,okay? So, before we delve into WB numbers and screw you up, you should understand how the ECM uses the NB's output. It uses AIT,TPS,MAF,O2 and various other sensors to determine how much fuel and or timing it needs to use to keep the engine efficient without making it detonate or making it a dog,also it needs to make the car driveable without stumbles,sags,bucking or stalling.
It's quite a juggling act when you think about how much information it needs to keep everybody happy and to simply focus on the O2 is ignoring many other factors. The O2 is actually one of the last things in that millisecond of data that is used and I guess you could use it as a judgement of how well the ECM is doing at controlling fueling and timing.
Problem comes when bigger turbos are installed or injectors don't match the chip's program that problems arise.
So, the O2 doesn't tell the ECM how much oxygen to add, but rather tells it how much is left in the burnt exhaust gases. The ECM determines how much fuel to add or subtract based on LV(load) vs. TPS.vs airflow,vs. coolant temps vs. outside air temp.vs.vehicle speed vs. gear in vs. altitude(MAP) etc,etc. It also adds or subracts timing advance too.
So my advise to you is to understand how a "closed loop" ECM functions, that will greatly reduce your learning curve and as you understand how that works you can see how a boosted engine requires different needs from that system.
I say that because people use stoich(14.7 A/F) is an ideal number but because a forced induction engine supplies much more air the ideal stoich is considerably lower,like 11 or 10.8. Then add methanol and average it's stoich (6.7) into the equation,because your dilluting the gasoline, and your numbers may want to be lower, like 10.3 depending on the percentage of alky being sprayed.Assuming too that you're running 93 unleaded. Now if your running race gas with a higher octane than your A/F target can be higher because it will be more resistant to detonation.
And of course lean is mean and fat is safe, but fast can be slow but lean means you can break shit.
So get a chip burnt for your cars application. Add a scanmaster and watch for detonation. It may detonate at NB numbers in the .780mv range and may not detonate in the .720 range...every car wants different things.
But in closing, right now learn about NB 02 tuning and forget stoich and wideband A/F numbers,mainly because they are inversed per say. Just concentrate on .0-1.o mv narrow band readings.
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