When to replace O2 sensors?

Actually I gotta correct this and say that it was excessive lean activity that killed your cat. Overly fueling a cat won't kill it nearly as quick as excessive heat generation due to unmetered air post MAF sensor.

Low AFR: not the best for things, but not irreversibly damaging either
High AFR: dangerous for cats and engine internals.

 

60K? Oh you're more then fine! Give it the Italian tune up every so often and you're good, which it sounds like you do regularly. I would just clean the throttle body. Your MAF is fine.

Those good old VTEC Hondas. Those were the days. Now they have iVTEC where you can't even feel that power kick in because it's throughout the entire band.

I've tried being tame in my driving, it doesn't change my fuel economy at all. I still get the same junky 260 (guessing here as I never take it down to 17.4 gallons which is the E light out of a 21 gal. tank) miles per tank. So I just blast it to redline every time I drive it because I like hearing the sound and power equal to a V8. Way too much fun. might as well smile as all that unburnt gas leaves your exhaust pipes right?

 

IF I can lay off, it does help but that is really asking alot.. and super boring..
I did it like once to prove it was me and not the truck.
I too never go to the gas light coming on - I tend to refill it around ½ tank b/c I don't like the way it feels without that extra weight back there..

With the MT you can make that truck move -
Just for giggles, I wonder how slow it would be compared to my neighbor's V8 Tundra with the AT now that you mention that..
You gotta use the whole power band, right - otherwise, what is it there for

I get lots of smiles as that gas gets guzzled and really don't think twice about it.
I like to drive, and there are costs [that I am willing to accept] for that.

 

You know, considering the mega weight on the Tundra, yours is pretty lightweight by comparison and you might actually keep up. I remember one time I raced a Dodge Ram Hemi and I kept up with him the entire way.

MT Tacoma's are overrated. They have issues that still have not been addressed well enough to be considered a permanent fixed to this day.

I have an AT by the way. Haha.

 

Glad you are able to get it to redline!!

My car in an AT, is sad and slow [even the BMW mag says so] + if you get the convertible version, the extra weight/way the body is weighted, also kills whatever fun but the MT is freaking amazingly fun to drive..

I love the MT and have never owned an AT - used to drive one OR for work all the time though; the inability to control the wheel spin as fine as I would like, drove me nuts - so when I went to buy a truck, it was a MT all the way.

 

Part of me wishes I could have bought an MT but my knees had other ideas for me. Knowing what I know now about the MT trucks it makes me glad I stuck to my original path of having to buy an AT.

 

I’m waiting for Rock Auto to deliver my sensors, but in the meantime was curious how tight they might be after 12 years and 185k miles.

Without disconnecting the wires, I was able to break both the upstream sensors loose with a 1/2” drive breaker bar.

Looks like the worst part of this job will be unhooking the wires, they’re between the engine and firewall in a difficult spot to see.

ETA: both downstream sensors broke loose without any trouble as well.

 

Changed the front O2's

took about an hour
Spark plugs should be here any day, due for those as well

I wonder if there's any benefit to replacing the fuel pump and fuel injectors or sending them out for rebuild

Car in question ran rich. It killed the cat.
Car responded to vacuum leak by increasing fuel to an excessive amount running rich. Which killed the cat by heating it to an excessive temperature. Causing a P0420 catalyst inefficiency code/CEL.
It consumed more fuel and smelled like gasoline.

 

My first and only one failed at about 99,000 miles but the others are still good, now at 124,000. If you really want to check them in the absence of codes, get a scanner that does real time data and recording to view the individual readings. I say just wait until they throw a code.

 

Any tips for the disconnecting the wires on the drivers side sensor? The Connection is between the Firewall and Engine and it’s hard to get and hand on it. The passenger side is easy but the drivers side is a PITA.

 

Get a chair. Climb up on the core support with your foot. Lay down over the engine cover. Use a blanket if you want to be comfortable. Carefully lean your arms in and gently pull any wiring aside. Don’t have the engine hot.

the clip is probably at the bottom. Squeeze the connector closed engaged first to relieve any tension on the locking tab. Spray silicone in the area to lubricate the connector. Depress the tab and then pull the connector apart.

You should be able to see visually where the tab is. If not use a mirror.

for me the hard part was 1,
The passenger side sensor turned hard and slow. I only let some penetrating oil sit on it for 4 hours.
Normally you’d want it to break free and then easily loosen by hand right after but it didn’t quite to that. The driver side did though.

2. the driver side was harder because of the brake system and lines in that area making less room. I did it from up top. Didn’t feel like lifting the truck and reaching up past or removing any skid plates.

I used a combination of o2 sensor related tools I already have:
-1/2” extra long flex head ratchet
-1/2”-drive oxygen sensor socket, generic
-22mm wrench
-oxygen sensor wrench, shitty brand
I hear snap on makes the best strongest oxygen sensor wrench in that it fits well and does not flex/bend/deflect however I don’t have one.

I’m glad I did it now because if not they would probably weld themselves into the exhaust.
I didn’t try to shock them with torch heat and cold water because I honestly didn’t expect them to put up as much of a fight as they did.

I knew the antisieze on them from factory on the new parts would help get them tight (if not too tight) so I tried not to go too crazy cranking down the new ones.

After that I ran the engine and sprayed soapy water to make sure there’s no bubbles to show an exhaust gas leak from them. And listened to make sure it didn’t sound like it.
So far no codes/CEL so I’d say it’s good.

I waited to plug them in after tightening so that the wire isn’t twisted and stressed. However one of them is a little twisted. I could always remove the sensor and choose a different position to start screwing it in (think of it like a clock, you can start turning from 6 o clock, 12 o clock, whatever)
But with how much of a pain it was to screw it in bit by bit I didn’t feel like doing that. It was only one side.
Wiring harnesses can have a twist designed into them from factory so it should be fine.
However they are a short harness by design if you get the right ones, so it may not like the twist as much as longer wires.

because the receiving connector that goes to the ECU is held on in the back of the engine area by a plastic clip that keeps it in one position. So the oxygen sensor connector has to be plugged in a certain way.
Again, silicone also helps connect it. But be careful not to spray silicone directly into the metal terminal pins.
Silicone on connector housings and plastic locking tabs? Great. Into terminal pins? Not needed.

also don’t forget to add:
-bunch of scrapes to your arm
-lots of curse words

 

I'm thinking of changing mine. My truck is 2006 @225,000 miles. I recently had the smog check done and everything passed and looked fine.
I have never changed them (bought it new) but they might be overdue for a replacement. I love my truck, all major parts have exceeded average life span.
Mine is 2.7L manual though, I heard these are the best Tacomas


Do these (O2 sensors) go bad little by little or do they blow up spontaneously needing immediate replacement?

 

They do go bad over time as the zerconia/titanium ages, it gets coated with soot, etc. They can also fail suddenly and throw a code/cause rough running. In THEORY, if there's that many miles, replacing them would reduce the possibility of sudden failure - especially in the heating element.

You MAY also see a SLIGHT increase in mileage with fresh sensors.

Over time, sensors degrade and become less sensitive or "slower" in reaction, which COULD lead to additional fuel being used unnecessarily.

I have personally never replaced one unless it caused problems - mostly because they can be such a PIA to remove, but I do know a few people that have replaced them just because of age.