I was just wondering, wouldn't it be a good idea to swap the rear o2 sensors with the front at some point? They are pretty much all the same, except that the front have shorter wires, but if you use Universal then it doesn't make a difference.
The benefit being that when you swap them, the rear o2 sensors are after the cats and therefore dont get as much heat and bad air since the cats filtered a lot of stuff out, so they should work better than the front sensors at this point, so when you switch them your MPG goes back up. The rear position only monitors exhaust gases, so it will most likely still be able to do its job, right...?

 

What engine?

 

They have different plugs...

 

ok they have different plugs, but you can cut and solder the plugs, so therefore you can switch them around. Saving on gas and over $120 on o2 sensors is a good idea, no? My gas mileage was down to 13 city... I'm putting my engine/tranny back in this weekend with all new o2 sensors in I'm expecting my mpg to be 17+ again. But I'm sure I could have just switched them around and had better mileage...

 

If you do not mind rewiring the sensors which seems to be the case from your comments, just put in the new generic sensors which have no plug. You can get them from numerous sources for around $75 each, possibly less. Make sure you get the heated sensors (I am pretty sure that is what all Audi's use). If you do this you will not have to worry about them for another 100,000+ miles as long as you do a good job splicing the wires.

 

Thats exactly what I did already. I got them for $55 each off ebay, and 1 from amazon cuz the guy sent one of mine to someone else. Whoa, what a day, I put my engine/transmission back in right now. I got lucky because I forgot to put a couple bolts into the rear drive shaft when it was almost completely in, but I was able to align the rear driveshaft with the output flange anyway, yay. Tomorrow I work, so Monday and Tuesday I'll be reconnecting everything, and cleaning all the parts, covers, etc that I took off and put in the trunk. Soo much work, but in the end my car will have much more power and drive like new. Yay

 

If you solder your ends onto universal wires, you have to use the proper solder. Regular lead based solder will affect the readings (or, so I am told).

Why did you have the engine and transmission out?

Bob

 

proper solder, lol you're funny. I work with electronics all the time, my hobby is flying rc planes and we gotta solder EVERYTHING, I even used to make little brushless motors when it was the craze, normal home depot solder is fine for anything trust me, whoever told you that is puffing smoke, lol.

I had my engine and tranmission out because transmission oil was leaking from between my engine and transmission (from the little holes in the bottom of the bell housing), and when I got the transmission out I discovered that my radial shaft seal (input shaft seal) on the transmission was worn and the spring is in it was stretched. It was also very very hard, compared to the new one, heat must have done that, and also there was a black ring around the torque converter which that seal seals, so is wasn't sealing anything anymore. Lots of work for a $12 part, but I also cleaned the engine and engine bay, gutted my precats and changed my cam plugs, and o2 sensors. My engine is still leaky, so I'll have to do the valve cover gaskets again (i only did the passenger side before) and the timing belt kit finally...

Did you know the apb enging has 258horsepower stock, it says so in the bentley, so with my darin intake and gutted precats I have almost 300hp unchipped. Yay, lol..