JDM 92 GT-Four RC Colorado Emissions, Catalytic Converter

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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby 92RC » Tue Dec 07, 2021 1:56 am

___Scott___ wrote:Just to make sure there is no confusion, the cat in the photo is completely gutted.


Oooooooooooh that makes a ton of sense, thanks for the clarification, it's bizarre the original listing said nothing about that https://jdmofmiami.com/product/exhaust- ... 051-74020/
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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby 92RC » Tue Dec 07, 2021 1:58 am

Roreri wrote:I am no expert on these matters, but as long as the exhaust coming out the tailpipe is in compliance, will anyone will care how you got there?

It doesn't surprise me at all that the JDM GT-Four has but one catalytic converter. As I have looked at mine, I do not see a second catalytic converter, and given the additional power of the JDM GT-Four, that's part of how.

If you got a pair of Magnaflows or whatever from the Advance Auto Parts and spliced them in there however and where-ever so they did the trick, would that work?


In Colorado it appears technically it matters but in actuality probably not. Like I said, if someone gives me a hard time A) I'm exempt from those rules due to the car being exempt, if someone doesn't see it that way it's going to be inconvenient for me B) I can't buy brand new factory Toyota Catalytic converters for this car unless someone finds something in a warehouse to sell me new old stock, aftermarket will be my only way to go.

My concern about the MagnaFlow will be going where it never was intended for on the JDM models, it's likely the exhaust won't need to be welded but it will need to be cut and clamped as a minimum. The car is lowered currently which might cause extra problems, maybe not.

Check out the image below and notice how different this US Market Celica exhaust pipe is (source https://www.amayama.com/en/genuine-cata ... ngine/1702) compared to the JDM diagram linked above, it looks like the pipe on mine could be cut between where it says "2" and "N" like where it is on the US Market ones.

Then this leaves me to the question do I take out the original cat and replace it with a straight pipe? I'm sure the shop wouldn't be cool with being associated with hollowing out the material in the original pipe, I don't have the tools, ability, and facility to do this myself at this time. I could in theory leave it in but perhaps it could lead to problems? I read an article "The Catalytic Converter should last the life of the car blah blah blah, you need to diagnose the cause of the failure first before blindly replacing the part" but could problem be old age? Were they intending this car to be roadworthy 30 years later with over ~150,000 Miles (~250,000 km) on the same converter? Sure it's Toyota but I don't think they anticipated the strict emissions requirements of the future.

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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby 92RC » Tue Dec 07, 2021 2:00 am

93celicaconv wrote:Makes one wonder if Toyota opted to use the exact same converter cast housing assembly for both models, but only included the converter guts in the USDM version?


Gee I hope not, wouldn't it smell kinda exhausty from day 1 if that were true? Out of curiosity I looked up a different Frame No. I found on Google (ST185-0003895) for a 1990 model (the RC models are only 91 and 92) and it does have a slightly different part number 25051-74010 instead of 25051-74020 on mine but it lists the price pretty similar.
https://www.toyodiy.com/parts/p_J_19900 ... _1701.html

This picture looks like it has some sort of Catalytic Converter material in it, here's the full page, it took a while for me to load https://raspil.su/detail/165588 (alt https://web.archive.org/web/20211207023 ... ail/165588)

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Image

ST185-0023348 is a 1992 BLMVZ model with the 25051-74020 https://bringatrailer.com/listing/1992- ... gt-four-2/
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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby 92RC » Tue Dec 07, 2021 2:01 am

simple wrote:Considering the MR2 uses that same downpipe I figured someone is selling one. Sure enough there is one on eBay for $300 with free shipping. Buy it, bolt it, and pass your emissions.


I noticed that one too, sadly it's used and I would probably have to inquire with the seller about the car it was parted out from (I mean, most people either talk up the part or they plead ignorance if there's a problem), my luck would be it might also be worn out and still fail. But by previous discussions if the American catalytic converters cost more, perhaps they're better at purifying the air? Maybe there's enough material left for me to pass and it would be a solid buy. The question is would it be a direct replacement.

https://www.ebay.com/itm/224102535120?h ... SwHfBfJhWq
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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby 92RC » Tue Dec 07, 2021 2:01 am

I appreciate your help so far everyone, hopefully I can narrow this down to a decision/the best option for me and start buying stuff soon. At this point we might have the most comprehensive "brain dump" of JDM catalytic converters and USA emissions requirements. We're almost to the point of "semi complete documentation" haha.
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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby simple » Tue Dec 07, 2021 2:50 am

Yeah you are overthinking it. Is this your only car or just for fun? You bought an exotic JDM car and are depending on mechanics to work on it? Do you have that kind of extra $$ to blow?

The ebay seller has a 30 day return window. So if you fail emissions with that part you can return it.

If you are near Golden I can help you with this project if you really can't turn a wrench or whatever. First thing is pulling the JDM downpipe and see if it is hollow.

Or spend $500 and have a muffler shop weld in an aftermarket 50 state cat wherever it can fit. It will not be in the factory location. Colorado aren't crazy strict like CA with visual tests.
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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby 92RC » Tue Dec 07, 2021 3:59 am

simple wrote:Yeah you are overthinking it.


Haha man have I heard that before. This is my fun car, just want to get it done correctly, I live in an apartment downtown Denver and I'm quickly realizing it's time to start renting a house to work on my cars easier. The main thing I'm afraid of at this point is my lack of experience putting the car in an undrivable state and me having it sit for a long time before I get around fixing it. I've been getting more adventurous overall with working on things so I'll get there.

That's a good point about the 30 day return window, I'll put some thought into that. I'll hit you up for sure if I need any local help! On one hand I'm only in theory spending $700 on parts and labor regardless of what it costs over top of that, on the other hand $300 plus not having to pay myself is another thing.
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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby simple » Tue Dec 07, 2021 4:07 am

You sound like me when I was in my early 20s. GTFO of hellhole Denver before your shit gets stolen. It happens constantly and cops don't care or can't do anything about it.
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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby underscore » Tue Dec 07, 2021 9:16 pm

The JDM cats definitely aren't hollow from the factory, I've seen mine and my friend gutter hers so there's definitely stuff in there. If anything I'd think the JDM cat is more heavy duty since it doesn't have a secondary after it and they've got that little temperature probe to tell if the cat is clogged up that the USDM ones don't have.
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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby 92RC » Tue Dec 07, 2021 10:56 pm

underscore wrote:The JDM cats definitely aren't hollow from the factory, I've seen mine and my friend gutter hers so there's definitely stuff in there. If anything I'd think the JDM cat is more heavy duty since it doesn't have a secondary after it and they've got that little temperature probe to tell if the cat is clogged up that the USDM ones don't have.


Thanks for this info, is the temperature probe droid plugged directly into the cat or is in proximity to it? I'm curious if I would have to bypass this if I go aftermarket.
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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby 92RC » Tue Dec 07, 2021 11:23 pm

Just some info about oxygen sensors, the USDM part # is 89465-29365 and the JDM part # is 89465-29355

Our friends at JDM of Miami have a picture of it https://jdmofmiami.com/product/sensor-o ... 465-20180/ and they do mention it's the same as 89465-20180

Image

GT4-Play has a Single Wire (out of stock) https://gt4-play.co.uk/shop/denso-02-ox ... st202-5983 and a 4 Wire https://gt4-play.co.uk/shop/denso-lambd ... st205-4451 but judging by my pictures it's a single wire sadly.

I'm seeing where to buy a used one that doesn't look completely trashed so maybe I'll need to buy that.

Edit: More info, I found this forum from some MR2 owners http://www.mr2.com/forums/threads/97154-Oxygen-sensor and the 2.2L NA MR2 for the USDM uses a single wire sensor that apparently works on JDM 3S-GTE MR2 models, Denso Part # 234-1056 https://shop.advanceautoparts.com/p/den ... 20471249-P so perhaps that is what I need for my Celica
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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby underscore » Wed Dec 08, 2021 6:47 am

92RC wrote:
underscore wrote:The JDM cats definitely aren't hollow from the factory, I've seen mine and my friend gutter hers so there's definitely stuff in there. If anything I'd think the JDM cat is more heavy duty since it doesn't have a secondary after it and they've got that little temperature probe to tell if the cat is clogged up that the USDM ones don't have.


Thanks for this info, is the temperature probe droid plugged directly into the cat or is in proximity to it? I'm curious if I would have to bypass this if I go aftermarket.


It's visible in these two pictures you posted

92RC wrote:This picture looks like it has some sort of Catalytic Converter material in it, here's the full page, it took a while for me to load https://raspil.su/detail/165588 (alt https://web.archive.org/web/20211207023 ... ail/165588)

Image
Image

ST185-0023348 is a 1992 BLMVZ model with the 25051-74020 https://bringatrailer.com/listing/1992- ... gt-four-2/


I've never heard of anyone being able to successfully remove one from the cat, they get insanely seized in there. Fortunately, due to the way the warning light operates, you can just unplug it with no issues.
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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby sefiroxx » Wed Dec 08, 2021 7:19 pm

Jumping in late:

Standard cat configuration for all models uses the downpipe cat (the one that is gutted). California models have a second cat added after the flex and around the resonator (long round pipe that is 2" wider in diameter)

The o2 sensor is a upstream sensor that provides information for fuel trim. Without a signal from the o2 sensor, the computer will go into open loop. Open loop is basically cold start with higher air and fuel thus the higher hc and co2.

Summary
- it looks like the engine is running rich and cool which would cause higher hc, co2 and low nox.
- you can use a paperclip with a old school analog meter to confirm the o2 sensor is working. The needle will bounce using this approach.
- gutted cat. I'm running one here in TX. With the 25 year car registered as "classic", I only have to pass see the safety test even in a smog county. Part of the exam is verifying that the smog devices are installed (but they don't test if they are working). If you did an import, they left the gutted cat in place to pass the physical import inspection (Ie seat belts)

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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby 92RC » Fri Dec 10, 2021 12:07 am

sefiroxx wrote:Jumping in late:

Standard cat configuration for all models uses the downpipe cat (the one that is gutted). California models have a second cat added after the flex and around the resonator (long round pipe that is 2" wider in diameter)

The o2 sensor is a upstream sensor that provides information for fuel trim. Without a signal from the o2 sensor, the computer will go into open loop. Open loop is basically cold start with higher air and fuel thus the higher hc and co2.

Summary
- it looks like the engine is running rich and cool which would cause higher hc, co2 and low nox.
- you can use a paperclip with a old school analog meter to confirm the o2 sensor is working. The needle will bounce using this approach.
- gutted cat. I'm running one here in TX. With the 25 year car registered as "classic", I only have to pass see the safety test even in a smog county. Part of the exam is verifying that the smog devices are installed (but they don't test if they are working). If you did an import, they left the gutted cat in place to pass the physical import inspection (Ie seat belts)

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I see! So that 100% lines up with bad O2 sensor, not bad catalytic converter (well at least not necessarily, the fact the NOx is low might be a good enough indicator that thing is doing its job). I looked up the Service Manual and I'm seeing what you're talking about, could I do it with a digital MultiMeter? I guess I could buy this one and add it to my quickly growing MultiMeter collection https://amzn.com/dp/B00002N5EX

Classic cars in Colorado have to be over 32 years old and need to pass an emissions test apparently so I'm out of luck there.

I called the shop I have it at and I mentioned "yeah I might take it to a place that specializes in emissions work" which they seemed to be OK with (they might be wanting to be gone with it which is understandable, they don't specialize in this sort of work), they're going to button up the other things I'd like done (I bought a Throttle Body Adapter & Coupler from GT4-Play and a Turbo To Intercooler Hose, I also want the charge cooler sensor wire rewired to the plug since it's just dangling from the plug). I went over the overview of information I found out and the guy I was talking to was like "um...yeah that's a lot I guess" (I have that effect on people). It's cool, hopefully they don't have trouble with the other stuff.

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Re: JDM 92 GT-Four RC Colorado Emissions, Catalytic Converte

Postby 93celicaconv » Fri Dec 10, 2021 12:01 pm

I think sefiroxx's response is an excellent summary of your situation, and his recommendations are spot on.

Your best bet is an analog DVOM (not digital), because what you are looking for are the cycles the O2 sensor should be putting out (easy to see the needle going back and forth at some frequency - very difficult to see those cycles on a digital display). I remember doing this on one of my early Celica's, and I do remember a frequency value that the O2 sesnsor must be at or above to consider it working right. I remember mine was much slower. I replaced it, and checked it, and the frequency of the swings was a fair amount above the minimum frequency on the new one, and the problems were resolved.
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