o2 voltage question

[wtngclan]

ok i have a simple question .. from what i have read at WOT the ideal o2 voltage is .92 to .94 .. if it is over .94 does that mean you are RICH OR LEAN.. i have read alot of conflicting threads

also if when tuning low throtle you are going for 0% fuel trim .. if it is negative is that mean your rich or lean? (and also what if your positive)

 

[Blk_99gst]

ok i have a simple question .. from what i have read at WOT the ideal o2 voltage is .92 to .94 .. if it is over .94 does that mean you are RICH OR LEAN.

I assume you have a 2g pocketlogger (please no blue wire mod on the safc). Also do you have a safc? What size injectors, stock?

You have read conflicting threads because the answer is not a definite one. The definite answer is NOT to use o2 voltages to tune by. They can't be trust, and can be different for everyone. BUT as a slight rule of thumb .94 is about the sweetspot, .92 would be getting a little too lean for my taste. But again, you shouldn't be using o2 to tune by. You should be using timing advance. Timing should drop to about 8degs when boost hits, and then climb up to about 18 or higher at the top of the gear. It should never dip during that process either.

i have read alot of conflicting threads also if when tuning low throtle you are going for 0% fuel trim .. if it is negative is that mean your rich or lean? (and also what if your positive)

Yes, tuning low throttle settings, you want to go for 0% fuel trims. It's almost impossible to maintain zero, so plus or minus 2 or so is good enough. You just don't wan to be plus or minus 15 or 20, that's out of tune.

If the fuel trim (short or long term) on the pocketlogger is showing a negative value (say -10%), then that means the ecu is having to remove 10% of the fuel using the fuel trim, i.e. you are 10% too rich. In this case, I would use the safc low settings and lean things out (so say you ar at -15% on the safc, then I'd lean it out to -20% and see how that affects the value. You might have to go the full 10% to -25%).

If the fuel trim (short or long term) on the pocketlogger is howing a positive value (say +10%), then that means the ecu is having to add 10% more fuel using the fuel trim, i.e. you are 10% too lean. Adjust the safc the overway then described above.

 

[wtngclan]

I assume you have a 2g pocketlogger (please no blue wire mod on the safc). Also do you have a safc? What size injectors, stock?

You have read conflicting threads because the answer is not a definite one. The definite answer is NOT to use o2 voltages to tune by. They can't be trust, and can be different for everyone. BUT as a slight rule of thumb .94 is about the sweetspot, .92 would be getting a little too lean for my taste. But again, you shouldn't be using o2 to tune by. You should be using timing advance. Timing should drop to about 8degs when boost hits, and then climb up to about 18 or higher at the top of the gear. It should never dip during that process either.


Yes, tuning low throttle settings, you want to go for 0% fuel trims. It's almost impossible to maintain zero, so plus or minus 2 or so is good enough. You just don't wan to be plus or minus 15 or 20, that's out of tune.

If the fuel trim (short or long term) on the pocketlogger is showing a negative value (say -10%), then that means the ecu is having to remove 10% of the fuel using the fuel trim, i.e. you are 10% too rich. In this case, I would use the safc low settings and lean things out (so say you ar at -15% on the safc, then I'd lean it out to -20% and see how that affects the value. You might have to go the full 10% to -25%).

If the fuel trim (short or long term) on the pocketlogger is howing a positive value (say +10%), then that means the ecu is having to add 10% more fuel using the fuel trim, i.e. you are 10% too lean. Adjust the safc the overway then described above.

i have a safc and i have 550 injectors .. im also using the scantool.net setup with digimoto software for logging .. im expecting my car back friday and wanted to try out tuning to see how this works .. so basically timing like u said shuld drop 8 degrees when boost hits and then go up to 18 at the top of the gear (18degrees or original value - 8 + 18) .. if theres a dip in the timing curve im under the impression that means i was too lean and i should richen it up? thanks for all this advice i appreciate it

 

[Blk_99gst]

i have a safc and i have 550 injectors .. im also using the scantool.net setup with digimoto software for logging .. im expecting my car back friday and wanted to try out tuning to see how this works .. so basically timing like u said shuld drop 8 degrees when boost hits and then go up to 18 at the top of the gear (18degrees or original value - 8 + 18) .. if theres a dip in the timing curve im under the impression that means i was too lean and i should richen it up? thanks for all this advice i appreciate it

So you can log and save data on your scan tool? Saving data and looking at it after the run is important. When I say 18 degs at the top of the gear, then I mean 18, no adding or subtracting. A 1 deg dip isn't the end of the world in timing or knock. We're talking about a dip where it's pulling timing badly as you go through the gear, instead of advancing it.

Here is a sample log from a while ago. Looking at it I think I'm a pretty rich, with o2 in the .98 and .96 range. I should have probably increased boost or leaned things out a little. I hit WOT (tps=98%), timing gets pulled down to 10, then creeps it's way back up to 21.