CaseyJones

Newbie here, first posting. I've searched pretty extensively and haven't been able to find answers to all my questions so hopefully somebody can help me out. Here's the rundown, with specific questions after the info. I have an '02 Tacoma SR5 extra cab, 4WD, 5spd, 2.7L, 120,000 miles. I live in Portland, OR First time CEL ever came on was as I was driving out of emissions testing station last year, after passing the test. Went on and off a few times than remained on. Checked the code, it was P0420. There's plenty of info on that, which I've read. Decided to leave it alone since truck still ran fine and I had my emissions tags already. Now I'm up for renewal of emissions and need to fix the problem. Went to a Toyota specialty mechanic to have my IAC unit replaced and asked him to look at the code issue. He didn't diagnose the cats or the sensors, but said that based on the code, the year, etc. he was 99% sure the cats were bad and both would need replacing, $2400 was the quote, he wouldn't use non-OEM parts and strongly discouraged doing so. The truck has 2 catalytic converters. Gulp! I believe him that the OEM parts are better and will last longer, I question whether the entire system needs replacing. 1. I am confused as to whether or not the '02 trucks differ in their emissions controls depending on whether they were a California truck or not. I bought mine on the east coast, where it lived most of its life but it was used and could have possibly originated in California, I'm not sure. Some folks have said that the California trucks have 2 cats and a different computer than the other49 trucks which only have 1 cat. Other people have said all of the '02 trucks are the same, have the same computers and 2 cats and meet federal and california standards regardless of where they were purchased. Any clarification on this please? The reason I ask is that I believe there is a small exhaust leak in one of the cats which is probably triggering the code. Since I need to replace at least one cat anyway but I'm not in california, I've considered going with a performance aftermarket exhaust that uses a single cat, but was told that eliminating one of the cats would mess up the california computer. But then I was told that all the computers were the same, hence the confusion. If I'm going to drop big bucks into the exhaust system, I want to get a little more power out of it, but I don't want to have to buy a new computer, and I need to get rid of that code to get through emissions. 2. Anyone have an '02 Tacoma out there with just 1 cat? 3. Anyone replace their original 2-cat system with a performance exhaust that only has one cat? Did this create any problems either with the computer, the CEL, or emissions? I don't want to replace the MAF and o2 sensors just yet because I suspect the exhaust leak is causing the problem and I want to get to the bottom of this california vs. non-california emissions configuration before I go any further with the aftermarket exhaust. Thoughts and comments greatly appreciated!

89-93-96-11pickup

if you need the cat replaced, check a local scrapyaard to see if they have any, then while your at it take your voltmeter and see if the ohms are in spec. then try clearing all the DTC's

sl0annuggets

Ok I just did it this weekend... I have a 2000 2.7 5spd that HAD 2 cats

I found a downpipe with a single cat for a federal emissions 4runner. Bought a New bosal muffler. Got both new denso o2 sensors.

Here is what you need to confuse your computer...

URD o2 simulator.
I ordered on friday afternoon and only paid 30 for overnight saturday delivery.
It will send the appropriate code to your computer to keep the check engine light from showing. I was getting 12mpg and with little to no power. I havent filled up yet, so I dont know about the mileage, but I definitely have my power back and the cost of this operation was only about 600 dollars in parts. It wasnt that hard to do (Sawzall recommended to get rid of the old stuff. But I had to go on a mission for gaskets because neither the muffler or the downpipe came with them.

sl0annuggets

Oh and one more thing. When you replace the o2 sensors you need the Cali spec ones NOT the 49 State.. The clips are different.

2349001 up front
and
2344154 in back

EnolaGaia

No, they don't ...

The LEV / California-spec versus Federal / non-Cali spec distinction ended with the 2000 model year on Tacomas.

The 2001 - 2004 generation Tacomas were all built to LEV spec's (i.e., 'California spec').

Erich_870

If you removed your stock 2 cat system and installed a single aftermarket cat and O2 simulator, why did you by 2 new O2 sensors?

I'll be replacing my 2 cat system in a couple weeks with a manufacturer spec'd setup I got off eBay from a place in Canada. They came highly recommended and the quality is top notch. I just ordered my new sensors today, so once I get them it goes to the shop.

Erich

JBSTRD

I have a 2000 Cali emissions 4Runner. I had the P0420 code a couple of years ago. I purchased two new Denso O2 sensors (actually 1 A/F sensor and 1 O2 sensor) and replaced them. I then had a local shop replace my two stock cats with "high flow" cats they stocked. I installed the URD O2 sensor simulator since the code would have thrown again since the "high flow" cats would not be up to Cali spec. The engine light has remained off for the past two years and the rig runs great.

I would recommend replacing both front and rear sensors, then installing the URD O2 sensor simulator so you know the sensors are good to begin with.

This code can be very frustrating to get rid of. Listen to others that have fixed this code. You do not have to spend the thousands of dollars the dealer charges to get it fixed.

Good luck.

Erich_870

I'm still trying to understand why you'd install two cats and two O2 sensors then install the 02 Simulator? Is it to pass a visual inspection?

Erich

CaseyJones

Thanks for the tips, especially the clarification regarding the Cali vs. Federal models...that makes it a little easier to assess my options.

It sounds like option 1 is to basically get the URD simulator, which would allow me to run any kind of cat system I want, using one of the high flow models, or to just keep my existing malfunctioning system in place as long as I don't have to worry about a visual inspection, which didn't happen last time I went in there.

Option 2 is to replace the o2 sensors first since I believe they are original and have 120k on them, then if no improvement move on to the cats. It might be worth taking it to a shop that has a scan tool for this in the event that only one cat is bad to save me the $of replacing both.

Option 3 is to move the hell out of the city since as soon as I get outside the city limits I don't have to worry about emissions. This is the most desirable but least likely to occur at the moment.

Will keep you posted, curious if anyone that used some of the high flow cats noticed significant performance/mpg gains from these systems.

Thanks

JBSTRD

I did not notice any increase in power with the "high flow" cats. Granted they were only $150 each.

James Woods

iTrader: (1)

Well, the DEQ station that I go to, all they do is look under the vehicle with a mirror to check for a cat, if the vehicle is newer than a 1996, they hook up their scanner and check for readiness of systems and CEL. You might get away with just getting the simulator and nothing else, you might as well try it, you dont pay if you fail.

sl0annuggets

One before cat and one after. The one after plugs into the simulator which goes to the truck..

Erich_870

Interesting. I was under the impression that the simulator completely replaced the second O2 sensor. That you just left in an old sensor in your exhaust and spliced the simulator in where an inspector wouldn't look, like behind the kick plate where the ECM is located.

[Edit] I guess my memory is outdated. I got onto URD's website and here is their installation instructions:

They don't specifically say if you have to have a working sensor, but it's probably safe to assume you do.

Erich

4runner joe

Ok well this is were I stand on this situation I have a 99 4runner with the same code situation and have noticed a lose in few and power. Now my 4runner came from PA but still has the cali emisions set up with two cats. Last year i installed a borla cat back and once i got it noticed it wouldn't fit correctly because of the two cat situation and i had no idea that this was an issue untill i got the exhaust in my hands (guess i should have read a little more before ordering). Well my question is what is an urd simulater and where do i purchase one? now i was also looking at going with a header and maybe the magnaflow high flow cat which would be a single cat setup so i can install the rest of the borla exhaust that is still sitting in my garage (i had to modify the stock exhaust to go with the new one) i.e. put and extension pipe on. and if im reading this correctly there is no difference in the computer that i would need to change. this really sucks in my situation because i live in ohio and there is no emitions checks or anything of that sort here. i would like to get the most power out of my truck as i can but. im needing some suggestion on what to do here. i dont know all the terms that all of u are useing considering this is my first toyota. i switched from the dark side (honda) lol. thanks for any help in advance.

Erich_870

Underdog Racing Development (URD): http://www.urdusa.com/index.html?osC...nq6i95uc30fba7

Here is their sensor page: http://www.urdusa.com/Electronics-Re...170/index.html

If what I mentioned above is the only option for Cali models, you'll have to keep your system with two 02 sensors. I know I'm not crazy that you used to have to splice in the rear simulator. It looks like URD modified the sensor to be plug and play (also reversible). They didn't use to have all the options to choose from, so that also corroborates my memory

Erich

sl0annuggets

Yeah, I didnt read so well myself. Once I realized I was trying to be cheap and get the federal emissions parts. I got all federal parts except the o2's they wont fit the harness. But everything lines up with the federal stuff just gotta have fed parts from the manifold back (minus o2's)

4runner joe

so no need for any computer parts? thats my main concern i have the cat back already just need the cat itself and i guess now the o2 sensors from what you have said. just dont want to put myself in the wrong spot. i did notice from exhaust diagrams that the flang on the single cat to the dual cat system where they meet to the manifold it looks like there is a differnce? correct me if im wrong here! just lookes like a even spaced three bolt on the dual cat system to a oblong shapped on the single cat system? sorry for all the questions but i want to make sure i make the right choice when its all said and done! thanks

CaseyJones

SO thanks for all the replies, I've reached the next decision phase of the project after some further exploration. I discovered that there was a small exhaust leak in the flange behind the rear cat but before the rear o2 sensor, tried repairing it with jb weld, but light is still on. There's also a small leak in the muffler but I don't think that would trigger the p0420 code. So I'm going to get a new denso rear o2 sensor, get the leaks in the flanges welded properly and see if that stops the code so I can pass emissions. IF NOT, then I'm going to get the URD simulator....which brings me to the next question.....

What exhaust to use?

If I'm going to be running the simulator it seems to me that I might as well take advantage of using a single high-flow cat and a bigger exhaust and a better muffler so I can get some power/mpg gains, right? Emissions should in theory be unimportant as long as I have a functioning o2 sensor and the URD simulator right? If my thinking is correct here then I could basically go from the headers back with a whole new exhaust system, high performance, single cat. Any recommendations for something like this? I don't want it to sound like a rice rocket or anything else for that matter, the only thing I'm interested in is better mileage and power.

I welcome your thoughts and comments

Erich_870

Update on cat replacement:

I got my rig back today after having an extensive list of work done. New cats, O2 sensors, spark plugs/wires, timing belt, water pump, block heater, and an oil change. I filled up on the way home and hope to see improvements in gas mileage over the next few tanks.

One thing I've noticed is this new cat system seems to have a vibration or resonance at around 20 MPH. It's a brand new sound for my rig, so I'm going to swing back by the shop and have them look it over.

Other then that I'm really happy with the power I've regained with the tune up. This tanks MPG will be a little lower due to all the fun I'm having

Erich

Erich_870

See my comments in RED...

Erich