ravensfan

iTrader: (5)

I want to completely tune out the O2 sensors so I never have to worry about emissions. Can this be done?

conan

iTrader: (5)

Rears yes, the fronts have to function.

Sales4@Texas-Speed

iTrader: (4)

Technically if you get a speed density tune you don't use any O2 sensors anymore, everything is based off the MAP sensor. However we don't like to speed density tune street cars because it takes away their ability to adapt to different temperature incoming air.

redtan

iTrader: (5)

Umm no, a speed density tune still uses O2 sensors.

An open loop tune is one that eliminates all oxygen sensor input.

777

iTrader: (21)

speed desnsity = front 02's only, no maf sensor

thatoneguybriz

iTrader: (2)

You can turn the rear O2's to a constant ready state with a good tuning software if I'm not mistaken. The nice thing about doing it that way is if you have to roll through an emissions test center where they just hook into your data port the system should ready ready and, if they dont do a visual inspection, you should pass.

Not that I'm implying you should break federal laws or anything...

Blk98Vert

iTrader: (2)

Yes you can, Ive seen it done

KILLER-LS1

iTrader: (18)

speed density can be tuned with or without O2 sensors. I don't have any stock sensors on my car, just the aftermarket wideband for my gauge.

And yes speed density still reads and compensates for different temperature. My IAT reads the incoming air, and depending on the temp its seeing, allows more or less timing. The IAT also sees my Meth injection and adds even more timing when it sees IAT Temp drop below a certain degree threshold.

yes it can be done, and yes you can drive it on the street that way. Will the A/F be perfect on a NA setup? Im not sure.., but on my FI application, the turbo is creating its own atmosphere that between my MAP sensor IAT sensor, and TPS, the PCM can tune it accordingly. All stock cars run in open loop (not using O2's) when they are warming up. Your car runs fine when its cold and in open loop.

RevGTO

iTrader: (12)

Yes you can do it and you don't have to have a speed density tune. You simply raise the closed loop threshold so that the car stays in open loop and fueling is determined by the AFR tables. I ran my car like this for over a year because I got sick of O2 codes and hassles after installing LT's.

ravensfan

iTrader: (5)

This is what I wanna do. I assume a decent shop could do this?

idlingmike

iTrader: (1)

FYI, before you do this, you will lose significant fuel economy with no o2 correction (front sensors) regardless or speed density or not. No trade-offs to ditching the rears. The front o2 sensors allow the computer to make constant tweaks to fuel trims during closed loop operation.

-Mike

RevGTO

iTrader: (12)

Not necessarily. The factory AFR tables need to be tweaked somewhat - mostly in the lean direction especially at colder ECT's - but I saw no difference in fuel economy. The main purpose of the feeback loop is to keep the AFR at stoich for the cats to be maximally effective. If you don't have cats or aren't worried about them, then you really don't need the feedback.

The AFR tables must be tuned with a wideband to insure that commanded AFR = actual AFR, or at least be close. This is done by tuning the MAF. This is a time consuming process and it would be expensive for a shop to do.

I went back to O2's because my car didn't seem to increase in power as the temps got colder running without them. That could have been the result of other issues, but I got a used set of Corvette rears and they have seemed to work well (although I had to tune out codes, as they continually threw them).

redtan

iTrader: (5)

If the tune is spot on, and the fueling is correct then there's no reason why it will lose fuel economy.

As far as MPGs go, it doesn't matter if the car is running 14.7 AFR at cruise from the o2 sensors telling it to do so vs. the car running at 14.7 AFR at cruise from other inputs besides the o2 sensors.

vetteman50

Hi Guy's,

My son has a 96 trans am LT-1 and has the rear O2's tuned out not there with long tube headers, and I'm trying to get it thru emissions and all but 3 readiness monitors are set so one is the EGR VVT? and the cat heater? I dont have them to the tee here at work but my question is they make these O2 simulators & testers would these work on the car or because the O2 is tuned out the signal from the tester will not be seen by the computer (ECU)?

Please advise,

Thanks,

Marc

xxrillixx

iTrader: (118)

Hey Marc, This thread is like a year old (since the last time someone posted) might want to start a new thread, or do some more research. Im not that familiar with the lt1's not readies like I am with the ls1. They do make simulators... probably your best bet. Or if you can find the rare person that still tunes LT1's, they maybe able to help you.

jr3277

I have had mine tuned out
I have a stroked ls1 and it's seen countless hours on dyno for many reasons. Right now the o2's are tuned out but I have noticed mpg way down an it loads up sometimes while at stop lights. I also notice pulsing while trying to maintain an average speed at any rpm
There could be other reasons for these problems but everything is pointing towards those o2's even though my tuner guy says it's not but this is the only change that has been made that could be causing this.
The car was making 405/405 at wheels an now it's down about 20hp.
Going to play with tuning tomorrow an will update on O2's.

I would say run the front o2's

kingtal0n

iTrader: (1)

This. The key is being able to monitor and adjust the a/f ratio while you drive, so that you can fix it when it wanders. The O2 sensors are for sheep to drive and not pay attention to the air fuel ratio. If you are not wanting to be like a sheep anymore, you put a wideband in the car, switch to open loop full time, and manually adjust your cruise a/f and timing for better than factory performance. ex. I run 15.2 to 15.4 air fuel ratio and slightly more timing and less vehicle weight that nets me the lowest EGT without pushing into diminishing returns. It can wander with the humidity, temps, and even electrical loading throughout the daily driving experience, mostly only near low injector pulse widths when using larger injectors. And that is where economy is happening i.e. cruising = low injector pulse demand, and the larger the injector the more likely it will wander from subtle changes.

eaglegoat

Or if you really know what you're doing you can adjust the o2 sensor tables so they do all of that for you anyway. Then all you have to worry about is driving and enjoying your car.

RixTrix

You might be able to pipe an output from the wide band to the ECU, I know the Innovate WB O2's have a second output that can be set to imitate a narrow band.