Bad O2's,,, again!!
 

So i replaced a set of bad o2's last summer before i had my dynotune done, Instantly got 26 miles to the gallon. a few months later the o2's were bad agian, fuel milage went down and car ran a little rough. replaced the bad o2's, cleared the code and got great fuel milage again. now im back to poor gas milage (went from 25 to 18 in a few weeks) and am pretty sure the o2's are on there way out the door again. I have 126,000 miles on the car, long tubes, ory, burns a little oil but no more than your average ls1. what is causing my o2's to crap the bed so early???

what brand are you using?

Have you used any RTV or other sealants on the engine? If so, did you make sure those sealants were "sensor-safe." (Certain types of silicone (I think it is) can contaminate the sensors.)

using bosh o2's for the corvette rear, i have long tubes and use these for the longer lead. no rtv sealants at all,,,, could burning a little bit of oil cause this? i usually have to add a quart between oil changes.

Ive read many threads downing the Bosch O2's. My guess is your one of many who has had shoty Bosch's. I think everyone reports Delcos are the way to go.

Denso 02 sensors are the way to go

Thanks for the correction

no - the sensors have heating elements that will burn off most contamination (there are just a few things - like silicone that they can't deal with.)

A GM dealer once told me that my K&N filter fouled them, but I never really bought in to that. The K&N definitely fouled my MAF, but there wasn't anything to prove that it had any impact on my O2s.

so burning alittle bit of oil wont foul out a sensor? how about a small exhaust leak behind the header? maybe i need to shore up my collector merges a bit more? is there anything other than some rtv sealant that could cause these o2 sensors to go bad? I just have a hard time believing i have had 4 "defective" o2's in a row go bad. Id like to fix the problem BEFOR i throw a set of densos at the car hoping it was just bad QC with the bosch sensors.

I'll bet your sensors are fine.

Have you checked for codes? What kind of air filter do you use? Are you running rough when its hot or cold?

O2s are just one of many sensors on the car that impact the air/fuel mix.

im using a k&n filter (should i ditch it?), dosnt run any different cold or hot really, just bad gas milage and kinda rough all around. gives me a little backfire if i run through a gear fast, then take my time shifting (rich condition right?). im probably going to work on sealing up the collectors a little better, maybe wrap them in exhaust wrap then put the collar back on, then make sure all the other sensors are clean and tidy. any other ideas???

Exhaust leaks even the tiniest will throw em off. MAybe try using some kind of heat wraps so they can warm up and stay warm.

Na - you may want to clean your MAF, though. That's probably not your entire problem, but it may help a tiny bit.

bought some silverish heat wrap, kinda thin stuff that is heat resistant to 2000 degrees, ill wrap the slip collector in a layer of this stuff then put the clamp back on. hopefully this will seal the collector up and stop any air from being pulled back into the exhaust. That and cleaning the filter and MAF up really well should take care of this problem (if it is due to a dirty MAF and the leaky collectors)

Back up to 28 mpg!!!! ended up being an exhaust leak right behind the o2's at the header merge. i took off the slip collars and wrapped the header/y pipe merge with an adhesive backed header wrap to seal it up. put the slip collar on over the header wrap and tightened it down. sounds better and the leak is gone. also poured a bottle of seafoam into the tank and cleaned the MAF with some deep creep.