Thread: Talk about your all-time bonehead moves

i'm going to let someone else take over from here, i get irritated and have a hard time putting my thoughts into words.

i've noticed on more then one occasion that the info you post isn't exactly correct, one example is the downpipe gasket.. so your join date tells me your new here and then you posting incorrect shit also tells me that.

i'm just as guilty of posting incorrect shit sometimes but i usually will admit that im either not sure or could be wrong, then when proven wrong i own up to it. however that doesn't happen as much these days as it did when i was new.

Bad O2 will mess with the AFR's while your in closed loop, in open loop your fuel map will determine AFR's. I've been running both of my turbo cars without an O2 sensor. P11 is NA right now with no front O2, it also had no front O2 when I was NA VE. No difference in drivability.



That is correct.



All but last bit is correct. Idle can be both closed and open loop. I personally watch it jump in and out on my OBD2 P11 with a scangauge.



You are correct, not sure what Josh is smoking today.

maybe im confusing open loop with closed loop?

my point is under cruise if you have numbers in the fuel map in the 190's or close to it, which is for using the o2 sensor feed back, if not you use numbers from 0 up.. unless im mistaken? so while idling or cruising around in that area your using the o2 feedback part of the map.. correct?

i too have been o2 sensor-less in my se-r for 3 years, and if you tune it to run the way you want without it, its fine. but say you load up a stock bin (even on a stock car) there will be afr differences with an without the sensor..

i know its best if your not going to use a sensor to actually just turn it off and tune with out it.

Open loop means ECU is not listening to the O2 sensor feedback and is using the values in each cell.

Closed loop means it first uses the value in the cell to get a base AFR. Which it then uses O2 sensor feedback to add or subtract fuel to keep it around 14.7afr.



If a fuel cell is above value 128, O2 sensor will be used in that cell if the O2 sensor flag is enabled. If the O2 sensor flag is disabled, or O2 sensor is missing it will take the cell value minus it from 192 and get the fuel amount to use.

So say you have a cell that is 200, we already know that 192 = 0, thus 200 = 8. But if we go in the reverse direction and have 180. This means the cell is actually -12. -12 is less fuel then 0.

This is why, even though I run without an O2 sensor, I still keep the feedback cells, it lets me lean out the mixture. If you don't use feedback cells the lowest value you can use is 0, no negatives allowed. Thus you would have to lean out your K value or injector scaling.




Actually every time you reset your ECU, the ECU goes back to using the stock map as a base, but then as you drive it it gathers O2 sensor readings for those cells and adds or removes fuel to keep it around 14.7. This is call your short term fuel trim.

Now there is a long term fuel trim too, that will take your average afrs for that cell since the last time you reset your ECU and will make adjustments based on that. This is why most small mods you don't see gains in gas mileage until way later. ECU self tunes itself to the new mod and reduces/adds fuel.

I personally don't like this, I want my car to run top notch and be fine tuned from the get go. This is why I have been running without an o2 sensor.




That is correct, if you have no O2 or have a faulty O2 disable the O2 sensor flag.

ok we're on the same page then. as i said i was having difficulty putting my thoughts into words. thanks V.

I'm not that worried about it. Seems as if your jimmies rustle easily (pun intended)
These cars are designed to be able to be driven without an O2 hooked up. Will it affect your cruising mpg's? Slightly. Will it affect low throttle emmissions? Yes.

And please don't equate join date to knowledge. I built my first setup in '01 and B series cars are all I've ever owned with the exception of my RL. I really like the comadre of this forum compared to others that I've been a part of and that's what drew me to finally make an account.

@ Vadim- thanks for clearing everything up for me.

Then we're in agreement

I had alot of stuff going on earlier that I wont bore you with, I try not to get too irritated and you'll find I'm a pretty chill dude, and I try to help out around here as much as I can. I also know join dates don't mean much but you gotta see where I'm coming from here? We get a alot of traffic and sometimes folks can be counter-productive

I know lol. I've just found that 90 percent of the serious hardcore build guys I've met never even go on forums. Where else are they supposed to find Craigslist deals?

You got that backward. A cold engine runs in open loop, ignoring the o2, and follows the cold engine enrichment trim and timing. At a predetermine engine temperature, say above 140F, it will then go into close loop and takes in the feedback from the o2. There's a reason why the o2 has a heater circuit.

I also don't run the the factory narrow band 02, but inorder for it too work well (good mileage, smooth running, good idle) it require a programable ecu and wideband for tuning. Not recommended if you have a stock ecu.

Oxygen sensor - Wikipedia, the free encyclopedia