Subject says it all......

What all does the O2 sensor affect?

What are the possible side affects of driving around with a bad O2 sensor?

Thanks,
STEPHEN

 

Also, what o2 sensors are you guys running? I'm not talking widebands here, just regular o2 sensors

Thanks

 

It affects light-throttle cruising, as the PFC goes closed-loop (adjusts the mixture by swinging it through stoic at 1-2 Hz for this load pattern). Under boost, high load, or high RPM, the PFC ignores the O2 sensor and just goes by the fuel maps. The stock ECU does the same thing. I think that the O2 sensor may be used at idle also, but I am not sure of the details.

I installed a heated O2 sensor from an 86 Escort (NAPA part #OS204), including running heater circuit power from the wiper motor, and a mating connector for the sensor that I got at a Ford dealer for $10. Heated sensors are said to last longer when leaded race fuel is used, though I have never tried that. It does smooth out the idle faster on cold starts. I might just get a cheap Bosch single-wire sensor if I did it again since I don't use leaded race fuel.

-Max

 

Interesting, the reason I was asking is I turned the o2 F/B control off and my car seems to run much smoother. It also seems to have better throttle response.

Should there be any side affects with is off??? It seemed to help alot.

Anyone else notice this???

Thanks for the reply Max,
STEPHEN

 

It has been mentioned a few times as the way to run if you had removed the air pump. The engine runs directly off the INJ map cells that way and does not try to lean out to control emissions.

 

Damn, I must have missed that. My o2 sensor went bad I was trying to figure out why I would really need it and couldnt come up with a reason. I decided to turn off the control and it made a nice difference to me.

I dont know if its my imagination or what but my low rpm power (2200-3500) seems to be much better.

I guess I never saw your post. Damn, I cant believe I actually missed one as much as I read around here. lol

Well, guess I can save my $$$ on the O2 sensor!!! Just more money to put toward a wideband.....every little bit helps

Thanks,
STEPHEN

 

I leave mine off too, and it runs a lot better. I figure why use an O2 when the PFC reads the cells anyways. I guess if you aren't fully tuned to a perfect A/F ratio under light throttle, it cleans things up a tad.. But, yeah.. I have no emissions devices on the car anyhow, so WTF?
Disclaimer: Heh em! I mean, you should never remove the emissions devices from your car, it's illegal and bad for the enviroment.
This vehicle is used for off road and race purposes only, and is never driven on public roads.

 

I have heard that your gas mileage will suffer terribly too.

 

The mileage will not suffer that much but driveability is a lot better. I leave mine on because I run the air pump and drive my car dayly in city traffic and want my engine internally clean as possible.

But there is a downside. In low revs in 1st and 2nd gear as you would be in stop and go traffic or in a parking garage, my engine will buck a little because of being too lean. If I turn the O2 controll off, the bucking stops and the O2 voltage will increase less than .1volt.

 

I've noticed that I can run a VERY lean idle with the O2 sensor feedback disabled, but with the O2 enabled the idle will get too low (3.4-3.3% inj duty), & sometimes stall.

Fuel economy does suffer slightly, but I figure if I lean out the Vacc part of the maps enough it'll be about as good.

I should be hitting the Dyno this weekend (finally) and should be getting my DIY WB kit together by the end of the month...