O2 sensor help

[wc00ac]

How can I check to see if my O2's are bad? And if I pull them out and my car still does the same thing then this could be my problem right? Thanks

[grandkodiak]

BEst way is to hook your car up to an OBD2 scanner of any sort and watch the readings that the O2's give.

[Breech]

One of the best indicator of bad O2s is poor fuel economy. Bad ones can yield around 1-2 mpg less or so than new ones. If you haven't done any mods to the car recently and you've noticed a decrease in economy and a little in overall performance, could be O2s but I'd be sure before I yanked them. If you have a 96 or up OBDII car then you have four of them to replace (2 precat, 2 postcat) and let me tell you from experience they are a serious PITA to replace. Not to mention a set of Bosch O2s from Kragen or Autozone will set ya back around $75-$80 a piece. All in all the money and time add up.

[Geo99M6Z]

One of the best indicator of bad O2s is poor fuel economy. Bad ones can yield around 1-2 mpg less or so than new ones. If you haven't done any mods to the car recently and you've noticed a decrease in economy and a little in overall performance, could be O2s but I'd be sure before I yanked them. If you have a 96 or up OBDII car then you have four of them to replace (2 precat, 2 postcat) and let me tell you from experience they are a serious PITA to replace. Not to mention a set of Bosch O2s from Kragen or Autozone will set ya back around $75-$80 a piece. All in all the money and time add up.

I've taken readings using EFILive, but what should I be looking for for bad O2 sensors. You mentioned bad fuel economy, I am getting that. I was getting 26-28 mpg, now I am getting 19-20. Not very good considering this gas price gouging !

Any advice that you could give me on the values that I should be getting that woudl be great. I can say that at WOT, the plot chart is smooth, but when I am driving at a "normal" speed at a constant speed the O2 chart is all over the board. Looks like a bunch of "noise."

[Breech]

Sorry Geo but I'm lost when it comes to that technical stuff, I have no clue what any of those readings mean I can tell you that with bad O2s I was getting about 12-13 mpg around town. New ones have me back up to 14.5-15 mpg city......if I don't get naughty with the throttle. Freeway has gone from 20-21 up to 23-25. My car is an A4 with 3.23's. I don't know how to give you any other point of reference. Maybe somebody who's good with the computer software can chime in and be of a bit more assistance. Just saw that you have a 99 so your mpg should be better than mine (LS1/LT1).

[Zboner]

also how many miles are on your car? maybe its just as simple as changing your plugs and wires? im having the same problems you are with mine man.

[wc00ac]

also how many miles are on your car? maybe its just as simple as changing your plugs and wires? im having the same problems you are with mine man.

This is a total rebuild of this motor replacing almost everything from oil filter to oil cap and then some. I haven't gotten it to run right since I finished the build.

[Zboner]

hum? let me know if your mileage does go up if you change your O2's man i really would like to know and it would help me out a lot with my problems.
thanks

[Geo99M6Z]

I have 140,000 on my car. The mileage just started going down recently before I change a bad knock sensor and wire. The knock sensor appeared to be bad.

Thinking it was the knock sensor causing the bad mileage, it obviously didn't fix the problem.

However I have noticed from my readings that the LTFTB1 & B2 are +15% and then some. NOT GOOD if it is adding fuel. I need to put some spark plugs at the tail pipes to burn that stuff off. Gas is expensive these days, i shouldn't be wasting it..

I'll let you know if replacing the O2 sensors fixes it. My car has been very good to me, just recently it is pushing the gas out.