I’ve replaced a lot of rear O2 sensors since I purchased the car. Every time I pull them out they are covered in black carbon. It seems ridiculous to replace O2 sensors once a year.
Does anyone have experience cleaning their O2 sensors with solvents or a torch instead of just replacing them? I know a few leaded fuel drag racers that torch their sensors to burn off the lead and carbon. Will that work with ours?
As for cleaning them, that’s a bit of a grey area, as it really depends on what caused the failure. What’s killing yours is most likely a different bag of issues, and it’s interesting you’ve gone through so many.
Do you often have the car turned on, but not the engine? Or turn the ignition on for a minute before starting? Basically, one of the O2 killers in street cars is condensation, and you live in a very humid climate… In comparison, I think I had 1 fail in the last 6 years. What downpipes are you running? More specifically, are the O2s installed at a downward angle? Other than the O2 failures, your car is running solid, right? No overly rich conditions?
The goal is for the engine to blow out all the condensation from the exhaust prior to the O2 sensor heating up. If you still have cats, water can pool at the bottom of them (lowest point). I just had a thought…I’m wondering if moisture can build up in the SAI system. You’ve deleted yours, right?
And since someone will probably bring it up, running leaded fuel is the opposite of above. Heat up the O2 prior to starting to help fend off fouling due to lead contamination.
I’m running the JHM downpipes without cats so there is a J bung coming out of the sides for the rear O2s. No SAI system.
I have had the car on without the engine running a lot since I last replaced the O2s in October. Mainly for testing various things. I’ll try avoiding this as much as possible.
Other than that the car is running really strong after replacing the rear O2s - long term fuel trims are slightly negative so overall the car is running slightly rich. At least I don’t have to worry about the front O2 sensors failing all the time too.
Thanks for chiming in koolade. P.S. I picked up a spare IM for testing the PCV mod - it’s at the machine shop now.
[quote=“komseh,post:3,topic:8938”]
Yeah, my vote would be condensation. It’s not that you can’t ever have the car on without it running. Just turn it off and let the O2s cool down before actually firing the motor in those cases.
If you’re up for it, take one of your dead sensors and cut away the shroud just below the threads and you can do a bit of an autopsy on it.
Do you have v-bands on your downpipes? Meaning, is it possible to rotate the test-pipe sections that have the J-bend so they’re sitting a bit higher relative to the DP?
Usually your going to see a lot of build up on the rear 02s they just dont get the blast the fronts get and depending on how your 02s are setting in the exhaust flow they can catch a lot of carbon.
You cant clearn your 02s with leaded fuel that actually kills them. The lead coats the 02 filiment and stops it from being able to function. You can use starter fluid or a quick evaporating cleaner.
Its always great to have koolade9 here as he has some incredibly good in site. the tips he gave are good ones to go by and will help the life of the sensor.
A few things to keep in mind. If your in stop and go traffic a lot you will experience a lot more carbon build up. If the motor gets too hot it will use extra fuel to cool the block down and the idea is to use lots of fuel and to not burn it all. Doing this helps cool the block down and usually the cats catch and burn off the raw fuel. the car runs rich and that raw fuel ends up cleaning off the front 02s but seem to clog the rear 02s.
A few healthy WOT blasts will help clean the rear 02s if you do that once or twice a week.
Also the J bungs create a great collection point for exhaust carbon. So like koolade suggested try making sure the j bung is rotated as much as possible to help restrict the ability for anything to settle