boraxman

My old oxygen sensor wasnt throwing any codes but had the miles on it. I picked up a brand new Bosch for my 3.4 for $58 shipped off Ebay. I put it in and have noticed better throttle response and increased mileage. Just sharing my experince

ebelen1

That's awesome. I want to do mine as well. Anything specific or just search 4runner bosch 02 sensor and it will pop up? Also, what kind of gas mileage increase did you get?

boraxman

Im not one to calculate MPG's, but honestly my gas gauge is hardly moving

I located the specific part# at some online part houses and then searced the Bay.

BajaRunner

Mine tends to stay still when Im sitting in it with my engine off too!

fireteacher

i am going to do this to, NOT sure how it helped the throtle response though....

boraxman

Ok I know its not very scientific, but the new o2 sensor made a difference.

midiwall

Actually... It makes perfect sense that your mileage and performance would change based on a new O2 sensor.

The ECU bases a LOT of it's fuel delivery decisions off of that front O2 sensor (or "A/FR sensor" on 99+ trucks). If it was cloggged, slow, etc. then it would feed bogus info to the ECU, which in turn could misread a LEAN or RICH condition and adversely affect the fuel delivery.

One thing that you'll want to do (if you haven't already) is to reset the ECU. If you don't, then the ECU will take _A WHILE_ to unlearn all the fuel trims that it's been applying. Reset the ECU by either pulling the negative battery cable for a minute, or pull the "EFI" fuse (under the hood) for a bit.


btw, it's interesting that the Bosch worked for you... A lot of folks have had trouble with them in the 3.4 engine.


and fwiw, Denso numbers can be found on URD's site. Use them to lookup O2 sensors on eBay or as crosses for other sensors, or to purchase direct.
http://www.urdusa.com/product_info.p...s_id=430006000

boraxman

Yes, I was a little leary about using Bosch(lots of bad press), however was a good price. BTW my truck uses a single o2 sens after the catalytic. I will reset the ECU, hadnt even thought about it...

fireteacher

i love going to school!!!!

midiwall

Wait... which O2 sensor did you replace? The one after the cat is really only there to verify that the cat is doing something. The ECU uses the front one.


Again, cool on the Bosch working. It sure beats the normal $90 price tag!

boraxman

I only have the one AFAIK, after the cat, 96 Taco. This is the one..

http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEAFB%3AIT

Got me thinking now...is there another one for sure?

midiwall

Oh wow... you only have one? like total only one? just one-one?

Is the exhaust system on the truck stock? If you look up in front of the cat, any chance that there's a wire hanging down with a connector on it that looks like it would hook up to an O2 sensor?

I thought we (96 3.4L's) all had two - short of the CA guys with a nightmare under there.

Interesting... Okay, my turn to learn!

HUTCHSTACO

i have 47000 miles, when would i want to replace mine, is it too soon, being he had almost 100,000 more miles than me?

boraxman

No, youre right. I had to go look and there is another one...guess im going to replace it too. Wonder if I should swap them for now..Hmmm.

boraxman

I hear you should change @ about 100k.

midiwall

Hmmm, okay then this is curious. I wonder why you saw any change in anything by replacing the rear one.

And yeah, you can swap 'em... The front and rear are the same on your truck.


Yeup, 90-100k. Or, if you're using something like Seafoam earlier than that, then they can get clogged up, but they're easily cleaned. The needing to replace comes from the element breaking down and the required chemical reaction which produces the voltage stops happening.

marko3xl3

About the rear o2 sensor...no matter how much you want to replace it, it's really only there to check if your cat is working. If it's broken, you'll get a CEL but it won't affect performance at all.

I replaced my front o2 @ 120k and didn't notice mileage improvements but for having 127k on my truck right now, it runs real good and pulls strong. +1 for preventative maintenance!

boraxman

Guys im not crazy..it feels totally different and I swear my milage is better, im gonna switch them and see what happens.

I emailed the seller to see if he has another one as I see he hass sold the same part before.

midiwall

Marko... this is whacked. What would the ECU be doing looking at the rear sensor? I mean, pure design logic says it's the wrong place to be sniffing fumes since it's post cat.

oooo.... I got one. What if the rear was choked, but not to the point of the ECU tossing a Bank 2 code, and the ECU was in some "safe" mode? Hmm, nah...

Okay, what if the cat's actually toast? He's got plenty of miles for that to be the case. But then, again, the ECU isn't designed to pay attention to the rear sensor.

How weird.


Mr. B. After you reset the ECU, let us know if you see a change in performance. Actually, it'd be interesting to reset the ECU, wait 100 miles, then move the rear O2 to the front, wait 100 miles, reset the ECU, wait 100 miles.

That's a lot of steps, but it may help sort things out.

MTL_4runner

Glad that worked out for you, but without a before and after gas mileage test it is very tough to say that it has actually improved gas mileage. Same thing with power......you might be able to feel some "seat of the pants" improvement but how much is tough to say.

I am a little leary myself of using any brand of O2 besides Denso (which the dealer and URD sell).