Do O2 sensors go bad all at once or is it gradual?

[BrettinSanAntonio]

I?ve noticed a strong fuel/exhaust odor when my ?95 Disco is warming up. I don?t notice it much after the engine reaches operating temperature. It also idles a bit rough until warm up. After that, it?s pretty smooth. Could this be a bad O2 sensor? Do O2 sensors go bad at once or is it a gradual decline in operation? I've got 135K on the Rover and my bet is the O2 sensors are stock.

 

[jeepfiend]

My experience has been that they gradually decline, unless they are hit with moisture or something foreign in the exhaust. On my '97 I had not had any problems with my O2's until I did the seafoam thing, and then I lost both the upstream sensors in just a few weeks. I think the '95 sensors are different, I believe 95's are OBDI, not OBDII, so I don't think the O2's are heated on the 95. It has been my experience that the non-heated sensors are more robust and will take a little more crap before they die. In that case, I would go with gradual failure. The rough idle has probably been getting progressively worse for a long time and now just got to the point that you are noticing it more. My DD is an 88 Isuzu, and that is how the problems with it are. Now that I have put close to 100K on it (305K total), I am starting to notice a few of the little reoccurring problems sooner. I am getting more in tune with the rig. I think that is inevitable with any 300k rig. Sorry for the birdwalk, but in short, yes I think they decline gradually.

 

[Joey]

Your issue sounds more like a leaking fuel injector than an O2 sensor, but that is just my opinion.

O2 sensors don't really start working till they get to operating temp, unless they are heated (first 5 -10 minutes). Since you don't have the heated O2 sensors (at least I don't think you do) then I would steer away from the O2 sensor thought myself.

 

[rovrjnky]

Ya, based on my experience, sounds like bad injectors.

 

[BrettinSanAntonio]

Injectors vs. O2 sensors

Well, that does make sense. I've been planning on replacing the injectors regardless so perhaps I'll start there and see what the outcome is. Out of curiosity, why would the exhaust/fuel odor go away after warm up if the injectors continued to leak? Could it be because the O2 sensors kicked in, and leaned out the mixture?

 

[Joey]

When the injectors are leaking, they leak off when the vehicle is not running, so after startup, they tend to run somewhat normally. They will start to burn more fuel, due to the fact that they are not working as effecent as they should be.

I wish I could explain better, but a lovely migraine is kicking in, so the old mind isn't clear.

 

[ptschram]

When the injectors are leaking, they leak off when the vehicle is not running, so after startup, they tend to run somewhat normally. They will start to burn more fuel, due to the fact that they are not working as effecent as they should be.

Depending upon how badly the injectors leak, the ECU will try to compensate for the leaking by leaning the A/F mixture. The ECU doesn't know, nor care why the uxhaust is what it is, it just tries to make it work.

As for O2 sensors, they usually begin to slow down in response until they stop responding completely.

The Rovers remain in open loop status until the sensors heat up and begin responding.

They are all heated.

Peace,
PT

 

[jeepfiend]

So even OBDI Rovers have heated O2's? That is interesting. It may not be that the injectors are bad, the o-rings could just be bad. My Trooper injectors have 305k on them and they are still going strong. I have had to replace the o-rings a time or two, but the injectors themselves are still going. As a matter of fact, I need to do the o-rings now, but have not gotten around to it. Good fuel and regular doses of injector cleaner can keep injectors in good shape for a long time. Yes they wear out, but I would think that 200k is attainable with good fuel. Just my two cents.

 

[rtiqulatendisco]

I've got 8 injectors that i will sell for a total of $100 and that includes shipping.

 

[ptschram]

I've got 8 injectors that i will sell for a total of $100 and that includes shipping.

New, cleaned??? OEM, aftermarket?

This enquiring mind is curious.

Peace,
PT

Paul@btlrovers.com