O2 Sensors and Oily Smell

[Zap]

Maybe we can solve the smell mystery once and for all...

It appears that there is more of an "oil fume / crankcase gas" smell when I am running with older oil, i.e. right before I change the oil. I'm wondering if this is rotten vacuum hose syndrome, charcoal canister problem, .. ? Any suggestions would be appreciated. I'm going to venture a guess that the smell isn't normal to the engine, but maybe that is the case.

Also, I wanted to confirm that replacing an oxygen sensor that isn't throwing any code has no benefit. I figured that it isn't worth spending $40 if it will work the same as the current one. I know there is a testing
procedure on SHOTimes, which I plan to use on the bad one (I think its the wiring, because it is intermittant), but I remember a debate in the past of whether replacing the sensors just because they are old does any good and I cannot remember what the conclusion was. I hope to maybe get under the car tomorrow and finally do away with the sporadic CE lights!

Thanks,
Chris

 

[SHOZ123]

I'm wondering if this is rotten vacuum hose syndrome, charcoal canister problem, .. ?

Check the big hose feeding into the bottom and back of the TB. This is the crankcase ventilation hose. There is also a hose on the TB to front valve cover, this is the crankcase air feed hose. It may be at the oil seperater under the intake too. The charcoal canister is strickly a gasoline fume item.

 

[Yamaha V6]

O2 sensor accuracy deteriorates with age - the CEL just tells you "it's pretty far gone".

Sure, annual O2 sensor replacements would help gas mileage, but will it improve your mileage to where you're gaining more than you're spending on the O2's? I'd consider 2 year cycles, or replacing them at your 60k maintenance cycles.

FYI, Standard Products O2 sensors have been giving me problems on the rare occasions I've used them over the past year. Motorcraft (made by Bosch) & the Autozone/Pep Boys Bosch ones have been far more reliable, though more expensive. Bought a Bosch for a customer's ATX yesterday for $49.99 + tax at Pep Boys.