Failing O2 sensors

[Rabbler]

It certainly isn't a horrible wave form but I would say it is a bit lazy. The slope looks a bit to wide. If they all looked like the 2nd slope I would say it was fine.

 

[NJC]

Thanks for your input Rabbler ... the O2 sensor is aged at ~10yrs and 70K miles so maybe it should be replaced anyway. My car has a severe rich idle condition though, and I doubt a new O2 sensor would reduce it that much (although I'm running out of ideas). 4.5% CO @ idle is HUGE - esp considering it was near to zero for the first 16yrs of testing. I've replace plugs, checked plug wire resistance. Air cleaner is OK. Vacuum hovers ~20in/hg. Leaking injectors? Faulty throttle position sensor? Driveshaft fluid

 

[Rabbler]

Could be just dirty injector Nozzles. Ever tried a injector power flush? With 20 inches of vacuum It should idle smooth. Can you feel any misfires or hiccups? Darn AirCare...

 

[mechtech2]

punisher - That is just plain wrong. Excess O2 is LEAN, not RICH. Bet your life on it.

 

[NJC]

It's supposed to take 50 - 100ms to switch from rich to lean. My sensor looks like ~500ms. In some cases, way longer. It's cycling, but taking way too long to do so, IMO. I'll replace.

 

[punisher]

 Originally Posted By: mechtech2

punisher - That is just plain wrong. Excess O2 is LEAN, not RICH. Bet your life on it.

I said that (see my later post, I was late for an appointment and typoed rich instead of lean). My original statement was that when you have a missfire, the PCM sees that as running lean and dumps more fuel in to compensate.

 Originally Posted By: mechtech2

punisher - A misfire allows the unburnt fuel to pass on to the O2 sensor. Therefore it HAS to be rich. This is why people argue with you.

That is just wrong according to what the PCM sees.

 

[NJC]

Replaced the sensor today with a NTK. Here's the old Bosch sensor 114K km/10yrs old. Bottom 3 pics are of each of 3 inlet ports - note only one looks completely clear. Not sure if this would impact idle emissions? Also cleaned dist cap contacts, they were slightly corroded. Post results after emissions test soon.

 

[StevieC]

That's one gross looking O2 sensor. I think you found the problem. And yes it would affect idle emissions because this is when the pollution is at it's worst (idling is very inefficient) and really needs the controls to work.

 

[NJC]

Coincides with the plugs too. Here's #4 plug, from recent plug change. I have a very slow coolant leak near #4 cylinder, but no way to verify if internal.

 

[StevieC]

I was going to mention coolant leak as well because of the white buildup on the O2 sensor...

 

[andyd]

that video of the DVOM bouncing between .1 and .8 V is what a good O2 sensor should do.

 

[Mr Nice]

Are you using any fuel additives ?

 

[NJC]

LT4 Vette - no, I've never used fuel additives. I drove my usual 23k km's to work this AM and exhaust smelled very clean upon arrival - hardly a trace of anything (er, except CO ).