Ok,
So it is my understanding that o2 sensors are good for about 100K miles...can anyone confirm?

Under heavy load I'm getting a rotten egg smell from the exhaust - sulfur from the cat... So I call a local old school muffler guy and ask how much for a new one and he asks me why. I explained the situation and he said that they smell like that when your engine burns too much fuel. So according to him the cat isn't the issue.

I called the dealer and confirmed via the VIN that my 4Runner does have the California emissions. - That means I have an upstream and a downstream O2 sensor. The parts guy then commented "wow, never knew anyone just to change an o2 sensor with out it being bad?"

So now I'm confused. Which is the issue? The Cat or the o2 sensor?

If it is the o2 sensor has anyone had issues with the "Universal o2 sensors"? I'm assuming I should stay away from those. I've heard that the upstream o2 sensor is the one that adjusts the fuel mixture and the downstream one checks for a difference. If this is true can I get away with only swapping the upstream sensor?

Just for kicks when I was on the phone with the parts guy from the local dealership the prices were as follows:
Upstream o2 sensor - $198
Downstream o2 Sensor - 172
New Cat - $1,077.80

Needless to say I'll pass on paying dealer part fees.

I'd really prefer not to just throw parts at the issue. Any thoughts?

 

I've always heard the Cat, but I just ran a google search and apparently replacing doesn't necessarily resolve it. Appears there's a TSB on the issue from Toyota. There's also other results that say basically the same things.

http://www.autosafety.org/Toyota%20S...l%20Models.pdf

http://www.delphifaq.com/faq/f1188.shtml

http://www.startribune.com/cars/11212206.html

I would guess the O2 sensor is probably working fine, but the cat may need replacing. You might try testing the sensor and inspecting the cat.

 

O2 sensors for this vehicle are supposed to be replaced every 60K miles.

Running O2 sensors beyond the extended intervals WILL cause the cat to plug/deteriorate. Keep that in mind for those of you that are cheapskates (there seems to be a lot around on this forum)

Get Denso O2 sensors from sparkplugs.com. They're same exact sensors as the dealer, but at a fraction of the price.

If you need to purchase a new cat, just get a good quality aftermarket one.

 

if it smells like rotting poo then its getting really hot and maybe even lowing in the night. this is from 2 things.... cloged or over fueling. hows your gas milage doing? air filter, plugs, wires, cap and rotor? if everythings good and it just smells bad then get a aftermarket cat or if it dont mater then go ahead and give a good ol cornholin you know hollow it out and you'll be all good but the cel will come on and stay on cause the upstream and the downstream will say the same

 

EGR valve maybe clogged..

 

pull codes.
If it's running rich enough to overheat the cat, the ECU should be storing a code about the mixture adjustments.

 

The MPG's have dropped substantially. I tried to pull the codes as per

http://www.off-road.com/toyota/tech/codes/

But all my CEL does is flash with out stopping or pausing no matter how long you leave it on. Any ideas on that? I used E1 and TE1

 

If your CEL is flashing at the same rate constantly with the diagnostic terminals jumped the you have no stored codes.

 

Crap. So much for easy...Now I guess I'll have to test the o2 sensors. Anyone done that with much success?

I picked this 4runner up at 112k (it now has 129K) so I have no clue when the o2 sensors or the cat was changed last (if ever). I do know the timing belt was changed at 100k - thats a good thing to know.

 

Mine has been making the same smell, I'm going to check the EGR before anything else, problem is, I don't have anything to pull a vacuum, which the test requires.

 

You wan the quick and dirty ghetto way? Put a piece of tube (or use the small piece that is on there) and suck on it. You will be able to tell if it is stuck open or not. If it is not the fire up you truck and suck on it again at idle. If it idles really bad or dies your valve works.

If you recycle the existing tube for your test - just wash it first.

 

Hey, that's not a bad idea...

 

It works...would you think less of me if I said I've done that before?....errr....uhhh....this guy I know...yea..he did it and told me it worked.

 

Not at all. As long as I don't get a lungful of hot exhaust haha...

 

The easiest way to check an EGR is to just manually push open the diaphram.



At idle you may not be able be able to tell if it's stuck closed. But if it's stuck open enough it'll idle crappy. Just push up on the metal part of the diaphram with a little screw driver to make sure it moves up and down. With the EGR valve off of the engine you can fill up one side of the line with carb clean and see if it drips through to the other side, indicating slightly open. Also make sure your vacuum lines aren't plugged. This is a basic diagnostic procedure, to be honest I really don't know toyotas very well.
And to check the O2. I always used really nice multimeter with minmax features on it. They'd average it out for you and slow it down so you could read it. You can always backprobe the sensor wires with a regular digital one and see what happens.
It's a two wire system (i think) so ground the negative somewhere. Then check the voltage of the wires while idling. While the O2 connector is plugged in take a sowing needle and an alligator clamp set up to back probe the connector.
One of the wires should be a constant 5 volts till the vehicle is at operating temperature (the power supply for heating the O2 on start up). While the other one will fluctuate rapidly in between 0.1 and 0.9 volts. Anything below 0.5 volts indicates a lean mixture while anything above 0.5 indicates a rich mixture. If the 02 sticks and stays constantly on a certain number I'd say it's shot. You can disconnect a vacuum line to make sure it goes lean and pinch the fuel return line to get it to run rich. Just try a few things to see if you can make it screw up.

 

Suck on the hose.

 

^
Just curious why would you suck on the hose when you can just push the diaphram up, it's accomplishing the exact same thing. Most EGR's you can get your finger in there no problem, these ones you just push a little screwdriver in the hole.
I'm not trying to start anything here, it just doesn't make any sense.

 

Found a guy on eBay selling a OEM Bosch downstream for $35 so I picked that up. Now I just need to find the upstream sensor and maybe I'll spot for a Magnaflow high flow cat. I dunno....

 

I just got an upstream NTK from Summit. Good price... Made by NGK. Heard too many complaints about Bosch, though I don't have first-hand experience.

 

Because.....auto mechanics is supposed to be dirty and nasty. The nastier it is, the harder you're working. Then, you're wife can't complain you're just out tinkering with the truck, again. That's domestic psychology 101!