striker754

iTrader: (53)

Do you guys just put both o2 sensors in the down pipe or what do you do with them?

If it matters, which I dont think it does, I'm going 3bar speed density.

onfire

iTrader: (17)

I'm not running any o2 sensors with 3bar SD.

You can run a semi closed loop 3bar sd and keep the front o2's if you want to....if you plan on running leaded gas just run open loop and don't install the o2's.

striker754

iTrader: (53)

It doesn't bother me either way. What is the easiest way to tune/setup? With O2s or without?

calongo_SS

iTrader: (7)

It's easiest to tune with a wideband, and then go back to the narrowbands once everything is dialed in. I don't know how running a closed loop setup full time on the street would work out, you'd probably be tweaking the tune all the time. If it's a race car that will be being tuned on all the time anyway than you should be fine.

cablebandit

iTrader: (37)

i run olsd all the time....o2s are in a box for emission time when i need to be in closed loop. I have been to Savannah twice this past month (500 mile roundtrip) and will drive to Orlando in october...900 mile roundtrip...in OLSD

striker754

iTrader: (53)

Its a street car. I do have a wideband. Doesn't the pcm use the o2s for cruising fuel control?

If you did use the O2s, just put them both in the downpipe?

Is open loop speed density any more different to tune?

calongo_SS

iTrader: (7)

You want to tune the car in open loop with the wideband regardless of weather or not you plan to use the stock o2's down the road. The tuning process would be the same until the end. Once everything is dialed in, you could enable closed loop and let the PCM use the o2's for part throttle fueling corrections (fuel trims), or you can leave the car in open loop and let all the fueling be done by the VE table. I've personally never ran a OLSD tune full time, but it sure seems to be working out for cablebandit. Maybe I'll give it a try when I get my car done.
It seems logical that both o2's should go in the dp, but I've never actually seen it done.

onfire

iTrader: (17)

Semi closed loop SD with the o2's installed will trim the AF ratio at idle and cruise to get it as close as possible to the AF that you command. If you want 14.63 : 1 , it will get you fairly close on hot days or cold days since it is constantly fine tuning up or down.

Open loop without the O2's will also get you close since the VE table will be the lookup table.....You will need a little more time to get the VE table calibrated as close as possible since you will not use O2's for fine tuning...only difference I see with OLSD is some days I'll get 14.5 and some days 14.8.....not a big deal to me since it's insignificant....and I don't have to worry about o2's going bad with leaded fuel.

onfire

iTrader: (17)

If you do use o2's....put both in the down pipe.

red beast

mine is tuned without o2's because I run 110 leaded fuel and it runs awesome on the street...

striker754

iTrader: (53)

so basically with the open loop you are using the tables to tell the pcm how much fuel to add and with semi closed loop you use the o2 sensors for idle and cruising to get to that fuel ratio? Is the only drawback small variations due to weather?

plus thats 2 less things for me to have to buy

Do you guys have any good places I can go to learn about tuning? I have HP Tuners and am going to purchase the 3bar programming for it. I'd like to learn to tune it myself so I can learn and know exactly what is going on. any help is appreciated!

calongo_SS

iTrader: (7)

In open loop the car uses the VE table only, in closed loop the car uses the VE table and makes small changes based on what the o2's are telling it. Either way the VE table is the primary source of fueling. You will see small changes due to weather variations in open loop. Depending on the changes in weather from season to season where you live you might have to have a couple of tunes.
As far as learning to tune, find some tuning guides to get you started, and go from there. The learning curve is pretty steep, you'll catch on pretty fast. I'm still a beginner, but it doesn't take long to learn. Just be aware that there is a lot of disinformation on the web.

Grr

iTrader: (2)

i run both o2's, right after the headers in the crossover. worked on the buicks, works fine on the 6.0. Also i run a full time CLSD with the 2-bar. The only problem people always say is that the o2's get too hot that close to the port, and if your tuning with them at WOT (like us buick guys did for 15 years) They scale down to high 700s or low 800's. ive never even had a wideband on my car, strictly plug reading and using the narrowbands full time, and its worked fantastic so far. And yes i know ill pick up some power with WB tuning and stuff, but thats for next year. So no flaming.
Gary