When to replace O2 sensors?

I heard with enough miles the O2 sensors on these trucks can start to die, not so severely that they trigger a CEL, but enough that they fail to properly read/measure AFR in real-time resulting in the truck running too rich and burning too much fuel

interesting coincidence that any time with my truck running it smells more like fuel than other cars for some reason.

on other brands/vehicles I wouldn't be surprised at all to see O2 sensors fail, both upstream and downstream, and have dealt with it before

has anyone replaced theirs as maintenance, or any other parts that could potentially cause worse MPG?
Is there a preferred source on good quality O2 sensors?
In my experience on other cars sometimes there is OEM match that looks identical, and aftermarket that can still work, same sensor, same connector, just really long wiring that the included instructions say to fold, tie up, and tuck away/hide (which looks ugly in the engine bay)

 

Denso.

The Toyota AFR sensors go bad somewhere between 120K - 200K+ miles. There will be mostly poor fuel economy coupled with a correlated degradation in proper fuel trim control. Which if left ignored for too long will burn out your catalytic converters.

If you are somewhere in that mileage and have never replaced them, you probably should.

 

exactly
Will do, thank you!

I dealt with a dead cat on another car before. Vacuum leak caused running rich = excessive temp killed the cat
Definitely not something I want to go through with the Tacoma having not one but two banks of exhaust and each unit being expensive on its own

 

Don't even think about supercharging it then. Haha. I've already blown through both of my cats in as little as 130K miles.

 

on one side, "87 octane is cheaper" - not anymore...
more hp/tq would sure be nice...
engine swap might be a cool project
everyone's seen the 5th gen T4R with 4.7L V8 supercharged, spins 40's

 

That thing must be wild.

I agree though. More HP/TQ out of these trucks is necessary really. Fuel is expensive no matter what now. Might as well enjoy your drive time. Smiles per gallon.

 

crazy to think they put ~220hp in a heavy high-drag truck with big tires when the average sedan at the time came with more than that

 

Try 181- 191 HP to the wheels.

These trucks easily need 50 HP more to the wheels to be even close to effective.

I love my 330 HP. Plus it sounds like a V8 now so wins all around.

 

according to rockauto PN's for 4L V6 are:

$112 DENSO 2349026 Denso 234-9026 Air Fuel Sensor

DENSO 2349026, downstream

$48 DENSO 2344260 Denso 234-4260 Oxygen Sensor

DENSO 2344260, upstream

assuming qty2 of each

hopefully the PN's are correct. RockAuto usually is

 

I wouldn't touch the lower O2 sensors. They don't see the type of voltage switching duty that the upper air fuel ratio sensors tend to see.

If you have a scanner however and see the sensor is literally not moving at all for a very long time (slow switching voltage is normal, fast indicates a bad cat, so it's normal when the cat is bad then it slows back down once the issue is remedied) then I would say replace it, outside of that, leave it.

 

The part number for the uppers are correct based on the quick search results I did for them. You are correct. Both sides are the same and the wire length will be a touch longer than OE but it's not a huge deal as long as they hook up and thread in properly.

 

how about ignition coils?

very common to replace those around 100k on regular cars

 

Not unless they are misfiring. To replace them any sooner is a waste of money unless you are after performance, that of which the coils on these trucks are about as stellar as they get for the power levels they handle and beyond.

Sidenote: if you have a question specifically for me, quote me or tag my name in your post that way I know you are asking something. I ran into the thread on accident as I was browsing the list of top posts of the forum.

 

I am a big fan of smiles/gallon!

I get shit MPG in my MT b/c of the way I drive

 

How much of a bitch is it to remove the old sensors? Any particular socket for this task that Taco World likes?

 

Define shit MPG. It can't be worse than my 14 MPG on the highway and in the city.

You need to get in touch with your inner Gumby if you want to be able to pull them off. They are in the most suck location I've ever seen. One more reason why I don't like Toyota. Haha.

 

The upstream ones at least are easy to access. I am worried how tight they might be after 185k mikes though.

 

Huh... I thought it was curiosity that killed that cat...







I'm here all week folks!

 

A slugging wrench works wonders. Sometimes with a little judicious heat. You can usually get a used 22mm off fleabay for short money. They also come six sided, though it's kind of rare. I have both a 12 point and a 6 point, and they both work equally well without rounding corners. Just a whack or two is usually all that's needed. Once it starts moving, use some Kroil or whatever to seep into the threads so you don't gall it.

 

They could be a problem but you won't know until you get in there.