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Discussion Starter #1
Hi all,
This is my second time to post on this great forum full of taco knowledge! I have a load of questions, so get ready.

The CEL came on a few weeks ago and the muffler shop told me that the catalytic converter was bad. They reset the light and it has not come yet again. Is this normal? I would think after driving a few hundred miles the CEL would be on again if the converter was really that bad. I know for a fact that the converter has not been changed since the truck had 74k miles on it so, it could be the factory cat!

Our Tacoma has 202k on it now and is running very good but I think it can do better.I get about 20-21 mpg (highway 65 mph) in this truck and I have read some people that get about 25-27. Have they done a ton of mods to get to this point or should my truck be capable of this? I'm not an aggressive driver and I do check the tire pressue and air filter.

Here is a list of the maintenance I have done recently.
Replaced spark plugs with NGK Iridiums
Oil- Pennzoil full synthetic 10w30 for high mileage vehicles (every 6k miles)
Seafoam treatment every 6 months or so
New belts

I have done quite a bit of reading lately and found a couple other things that should probably be looked at such as:
Cleaning the throttle body (yes the gas pedal sticks slightly upon first take-off)
Clean the MAF sensor (how important is this and do you feel the truck will benefit in any way?)
Distributor cap?
Fuel filter? this has never been changed to my knowledge.

We need this truck to last another 100k with no serious issues (I have faith in it). My husband and I are not mechanics but I do my best to keep our trucks in great running condition. I have two mechanics that I can go to and say "do this" and it will get done. But they never tell me what "needs to be done."
So with all that said, any Taco advice on increasing fuel mileage and longevity is greatly appreciated!
 

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YEP... I'MMA DOUCH3
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20-21MPG is fair considering the truck has over 200K on the ODO... Since it's a 2.7, chances are that it is a pre-runner, and has larger tires, which also is a good reason why the mpgs are lower... and it's a 2002 so it doesn't have a "distributor," it has a COP (Coil On Plug) design which means more reliability. As far as the cat is concerned- if you got a CEL code P0420- then yes, it will come back on and soon- but who knows what the "real" issue is, as your mechanic cleared the code.
 

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Discussion Starter #3
Ok thanks. Now, I am getting confused about the converter. Are there two converters on these trucks, one in front and one in rear?
Or is there one converter that is located in either the front or the rear?

The mechanic made it sound like there are 2 converters but the autozone person made it seem like there was only one.
Help here!
 

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YEP... I'MMA DOUCH3
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There are two cats on your 2002, and both can fail (although usually it's the top cat that goes first), if the cats (one or both) the code would come up almost immediately after clearing it. There may have been an intermittent issue with the ECU, which may have been the issue to start, but again without the actual code, we're guessing what issue really may be.
 

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Discussion Starter #5
Well that is interesting. It has been a week since the code was cleared and the truck is driven about 30 miles every day. So it must not actually be the cat. converter that is the problem if you say the CEL will come on almost immediately.

This may be a dumb question but does autozone or oreilly's CEL check thing give the same codes? They always give me such vague answers but I never actually get to see the code. Maybe I should get a CEL scanner or code reader of my own!

I think I may wait until the CEL comes on again before I spend $200 on a converter replacement that I may not necessarily need. What do you think?

Truck maintenance is really frustrating sometimes....
 

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Discussion Starter #6
Ok so the CEL came back on finally. I got a second opinion from another mechanic shop. They diagnosed the truck for me. o2 sensors are working great except the rear sensor is a little sluggish. Bank 1 cat. converter is inefficient and needs to be replaced. My quote was $260 to install a new converter from this shop or $189 from the other shop.
My next question is how much of a headache is it to remove the ineffective cat and place a rear O2 simulator in the truck? I think a URD simulator is about $104. We don't have emissions tests where I live. With this truck having so many miles on it, I really don't want to put anymore money into it than I have to. So I am torn between what to do!
 

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Mambeau / Admin
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I'd suggest replacing the inefficient cat and see where that leaves you ... Unless this latest shop meant the rear O2 sensor was going bad in and of itself, it's possible the sensor's 'sluggishness' might be the result of the bad cat.
 

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Discussion Starter #8
Ok I think we are going to yank a converter out of our friends salvaged ford explorer and try to put in our truck! lol The converters look similar best I can tell from internet photos.

Wish us luck on the cheap route!

By the way, how many miles do you typically see out of the toyota automatic transmissions?
 

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Discussion Starter #9
Well I am beyond angry right now.:mad: I spent the $200 to have a new converter put in my truck but low and behold the mechanics all of a sudden find the up stream O2 sensor is bad. They tell me they can't warranty the work on the catalytic converter unless I spend an extra $235 to fix the O2 sensor! AND they won't give me my old converter back unless I pay some $60 core charge which was never mentioned before. I should have gutted the stupid thing and been done with it.....

I have looked at autozone O2 sensors and the one I need is $179. I found one for $50 on autopartswarehouse. It is an Auto Trust Plantinum, has a 5 year warranty and is the 4-wire sensor. It claims to work all all 2002 Tacoma models.

Will this sensor work just as well as the Denso ones from autozone or oreilly's?
 

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Mambeau / Admin
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The 'factory spec' EPA mileage estimates for a 2002 3RZ PreRunner are 19 city and 22 highway. Your reported figures are exactly centered in this range. I'd say that's doing darned well for 200,000+ miles. :thinking:
 

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Mambeau / Admin
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Did the mechanic(s) specify which code is being thrown? We really need some solid clues ... :shrug:
 

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Discussion Starter #12
Well ok if you all say so! Lol I guess it is human nature to want more! Haha
It just seems like it used to get better than what it does now.
Any suggestion on an o2 aka A/F sensor? Will the $50 one work or
Do I really have to buy the $150 one from urd?
 

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Discussion Starter #13
No they just said they couldn't get the codes cleared so they checked all the wires and then determined that it was legitimately throwing the bank 1 sensor code. But they did not show me the code numbers so I can't be for sure if they are right. :( the last time the sensor was changed was at 74k miles.....I don't know how long they generally last but that seems long to me!
 

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Mambeau / Admin
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Here's the problem ...

There's no such thing as a diagnostic code that definitely and uniquely means the Bank 1 Sensor 1 A/F sensor is 'bad'. Problems with the sensor wiring, the ECM, EFI relay, and a host of other things might be 'in play'. Depending on the exact code condition, it could be something like an exhaust leak or a problem with the air intake.

I'm not saying it can't be the sensor. All I'm saying is that we can't specify any (of the possibly numerous alternative 'suspects') if we don't know exactly what code is being thrown.

After about 130,000 miles, though, it wouldn't be surprising if the A/F sensor gave up the ghost.

On some components (e.g., spark plugs) Tacomas are notoriously finicky and clearly work best with the (typically Japanese) components they originally had. If it were me, I'd definitely get the OEM-like Denso, because I'd be treating this as a presumably 100,000+ mile investment. Just my .02 ...
 

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^^^^^^Hit the nail on the head. :waytogo:

and sorry you got screwed by that shop.

personally if you want to keep the truck, id put the oem 02 sensor in it. if your still throwing a code (CEL is on) id gut the cat you didnt replace (since its pretty old at 200k) and get a o2 sim from URD for the rear.
 

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Discussion Starter #16
I see your point. Maybe I should just buy my own code reader and pull them myself???
Will autozone or oreilly's code reader spit out the codes you need to help me???

As far as the spark plugs go, I never read anything about the NGK iridiums causing any problems for the tacomas. So I thought they would be good to use. Did I miss a thread where these have been a problem?

Ugh I am at a loss here.....I'm ready to put a sticker over that CEL and just ignore the thing. :rolleyes:
 

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Discussion Starter #18
sounds like good advice there too.
Yes we are keeping the little truck...it is paid for! :)

Yeah I hated to use a mechanic shop that I was unfamiliar with but didn't have much choice.....next time my husband will be dealing with the jerks. lol
 

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Discussion Starter #20
Just kidding! So....... I need help choosing the correct O2 sensor. :doah:
I need the Denso 4 wire sensor that goes in front of the converter.
There are like 4 of them! :eyecrazy:
I really like the one for $67.....ya think it will work?
This forum is not letting me post links so I can only tell you that I am looking at the denso sensors for my 2002 2.7L Tacoma on autopartswarehouse.com

Any help is greatly appreciated!
 
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