JDM 92 GT-Four RC Colorado Emissions, Catalytic Converter

9

92RC

Member
Hi everyone,

Sorry for the super lengthy post, I'm mostly trying to get all of my thoughts in one place so far. I got a call a couple weeks ago from the shop my Celica is in currently and they're telling me I need a new catalytic converter to pass emissions. Has anyone here done this recently? The shop doesn't specialize in JDM cars (or emissions for that matter, more info on that below) and they're having a hard time finding parts (the 2 places I've gone to so far I've done most of the research and leg work for them, I have no problem continuing that since I knew what I was getting into when I bought this).

Edit: This was actually fixed by an oxygen sensor, if you have similar emissions test results continue reading because this thread addresses troubleshooting a bad sensor, finding the correct part (or a part that will work), verifying the new sensor works, and retesting at an emissions testing center. The Catalytic converter was a red herring and could be a costly way to not fix the problem.

I mistakenly read in the US owner's manual I bought that there was only the downpipe catalytic converter and have been all like "I don't think a generic will work because it's a downpipe one blah blah blah" "it needs to be specific for this model blah blah" and I started searching this forum and realized at least the US models have 2, is that the same for the JDM models?

The owner's manual I have matches the picture in this thread viewtopic.php?p=214568 with the text "5S-FE engine for California and 3S-GTE"

I found this forum here from 2011 viewtopic.php?f=7&t=41555

The link there is for this part:

https://shop.advanceautoparts.com/p/mag ... 22317292-P

Cross referencing MagnaFlow's website it appears to be the same part:

https://www.magnaflow.com/products/9100 ... -converter

This all being said...

Research on RockAuto & Summit Racing shows some reasonable prices on items that appear to be a direct fit for the Celica (so in theory no welding) for what appears to be 2 different types and seem to match the description/diagram, the RockAuto ones apparently are "not legal for sale or use in California or Colorado" but I'm exempt from the "use" part since the vehicle is exempt through the 25 year rule, I'll drive it to a different state to get the work done if needed (I mean, do they want my registration money or not? :p). Obviously if I went the universal route I'm not sure what I would do about the front converter so this seems appealing to me.

https://www.summitracing.com/search/par ... 3Aall-trac

https://www.rockauto.com/en/catalog/toy ... erter,5808

I was able to find the part number for the original discontinued downpipe Cat which is 25508-74110 https://parts.toyota.com/p/Toyota__/Cat ... 74110.html but I have no idea where I can find the other part number, it likely doesn't matter since that's probably discontinued as well

The reason why I'm looking all of this up is because the shop I'm working with mentioned they're not sure if I need something super specific for the car to prevent problems. Does it really matter for these cars? Obviously I'll get some performance gains hollowing it out (I don't know if that's a common practice in Japan but maybe a previous owner did that and that's why I'm having problems?) but if it's about the same for bolt in parts I'm not super concerned, the car is fast and fun as it is and not modern enough for me to think it would be a huge problem. I have heard of non oem converters getting clogged up before, would that be something I would have to research or is that just a problem for the typical "EBay special" cat? I guess I could even get something like this from GT4-Play https://gt4-play.co.uk/shop/sports-cat-down-pipe if I cared about performance, I've bought from them before and they seem to have good stuff and good customer service.

On a related note

The shop also was having trouble with the oxygen sensor they bought, I only saw the 1 on there, are there any more? The one that's on there "wasn't communicating with the car", the service writer I've been working with mentioned they determined the JDM sensor likely is different but I can't seem to find any JDM part numbers for it (plus that doesn't sound right to me, obviously the ECU is different so it could be true but most of the part numbers I've encountered so far are the same as the American ones). I did find a discontinued part 89465-29365 but again, I'm not sure if that's the correct one.

https://parts.toyota.com/p/Toyota__/Oxy ... 29365.html

Pictured is my oxygen sensor and the questionable looking cord coming from it


Should I just cut my losses and take it to a place that specializes in emissions work? When I failed I was provided with a booklet containing info and certified shops from Air Care Colorado so I'm sure I could call any one of them up and see if they have any experience with JDM cars. For all I know (which isn't much) it could be something else and the cat is fine.

If anyone is curious on the results of my emissions test, here's that.







Here's a video of a part of the test, I think the total test was about 10 minutes
https://www.youtube.com/watch?v=TU86iZAruV8

The second emissions check I got in September was pretty close:

HC GPM was 2.2149 (needs to be below 1.5)
CO GPM was 74.1607 (needs to be below 15)
CO2 GPM was 427.4416 (no limit specified)
NOx GPM was .9860 (needs to be below 3.5 so that's nice)

This was a different testing location but the main thing that changed was I had the spark plugs changed and I had a 54 engine light (I read up on this ToyotaOwnersClub post https://www.toyotaownersclub.com/forums ... 6-code-54/ and did the whole coolant top off thing without success, I then noticed the wire was simply corroded and dangling so I was able to tape it in place) which puts the car into a limp mode of sorts. I haven't had the distributor cap changed but that might another thing to do related to this whole emissions thing. The first test was at a facility for the department of revenue, I asked them "what typically would fix cars with results like this?" "Oh any Toyota shop should get you fixed right up, not a big deal." Thanks a lot guys, this is appearing to be...a big deal.

Colorado doesn't have the same strict requirements California does (yet) but it's my understanding they want to limit sale on incorrect/generic catalytic converters to avoid people cheating and putting the wrong ones on. Someone at the Denver DMV told me to save my receipts because they'll "provide me a voucher for anything costing more than $700" (so I guess that means if I pay over $700 they'll cover the rest of my costs) so by golly if they want to phone up Toyota headquarters in Japan and special order me 2 factory catalytic converts and pay for it I'm in. If all else fails I'll do the thing that people heavily frown upon (but it isn't illegal) and get the car registered in a different state.

What do y'all think?
 
simple

simple

Active member
Long post that I don't have much input on. Front Range CO has a major smog problem so they adopted strict standards. You don't have to register in another state just a county outside of the front range that doesn't do emissions testing.

Or have a cat welded on and you'll likely pass just fine.
 
underscore

underscore

Well-known member
My RC passed aircare up here before I bought it, so they can certainly do it. Granted I don't know if the measurements were more or less strict than yours are now.

If you've got a code 54 the car is going to be running safer so the odds of you failing the test are higher. I'd get that sorted out before worrying about anything else.

Since there's no OBD system to connect to I'm curious how they determined the O2 sensor isn't communicating. There is only the one, one wire sensor on these. Similarly I assume it's just a sniffer test at the muffler because that's all they can do with these, is it all done just at idle? If so then you should be able to just make a note of the current settings, then adjust the car to run as lean as possible while still running, test it, then put it back. If you do add/replace a cat I'm not sure why they should care if it's factory or not, if it gets the emissions below the limits they want then who the heck cares what cats were used to achieve it?
 
9

92RC

Member
My understanding is the requirements haven't ever changed for AirCare, they just have certain ranges of requirements by year of manufacturer, I think the range I fall into is 1980-1996 (the first year of OBD2 being required, I might be slightly off on the dates).

Makes sense about the 54, I hadn't done the paperclip error code trick before getting the emissions checked. I think they're going to rewire the wires for the sensor for me so I won't have to worry about that anymore.

I read somewhere the "Diagnosis" plug in the engine bay is OBD1 compatible (I have the adapter cable, I've only tested with a OBD2 only scanner which did not work but it did power on so it's something) but I don't have access to a scanner with that functionality to confirm, the ones I'm finding online around the $250 pricepoint are either code only scanners or the reviews say they actually can't read OBD1. Can one do such a thing with OBD1 or was that not available yet?

I was thinking the same thing about them maybe not knowing about the sensor or not, the place I normally go to I mostly talk with the owner who does a lot of the work so I can get the technical info (they don't do any emissions work pretty much) but this place I don't talk directly with the techs so it's possible it's summarized to the service writers and then summarized to me and I don't have all the info.

AirCare puts the car on a dyno (it's a good way for me to tell the AWD system is working haha) for their tests but my shop either has the car in the air or just revs it when the car is stationary, I'm pretty sure I didn't see a dyno there but it's possible I guess.

That was my thought on the cat restrictions, I'm sure it's Colorado trying to do some "productive" legislation that doesn't actually change anything.
 
9

92RC

Member
Gotcha, well mine has 250,000 km and it smelled like exhaust the day I picked it up from the port so if yours smells fine you might not need to go through the trouble I’m going through. I read your first post there and I might need to follow some of your threads, a lot of the maintenance you’ve had done to your car I’ve either done or need to have done and some of the things you’ve mentioned I’ve never heard of before and I’ll have to look into. The inspection on my car was mostly “yup looks good, other than the axle boots.”, not the most comprehensive thing in the world, hell my front washer sprayers don’t work, I got problems haha.
 
9

92RC

Member
Quick update, I kind poster here on this forum PM'd me with some info from ToyoDIY.com, I wasn't able to find this chart on Nengun.com's site (I'm sure it's there but I was just having a hard time finding it) but it appears there are 2 mufflers, 1 resonator, and only 1 catalytic converter. Perhaps the resonator is in place of where the 2nd catalytic converter is on US market models.




Strangely, this chart doesn't show the exact converter but instead this sub-assembly pipe (unless that is the cat, it does look like it has some weird textured stuff on the inside). I'm going to call my mechanic and ask them to take a picture of the exhaust on the lift, just to triple check. I'm really leaning toward the GT4Play converter but I'm still not sure.


 
R

Roreri

Active member
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?
 
9

93celicaconv

Member
underscore":2mzuiz6j said:
Yeah that crazy factory downpipe is the cat.
Click to expand...
Yes it is the CAT. It just doesn't have any of the internal contents inside of it. Which is interesting.

The USDM ST185 manifold converter sub-assy P/N is 25508-74110 and listed for $851.00 in the early 1990's. The JDM ST185 manifold converter sub-assy shown on 92RC's vehicle is P/N 25051-74020 and listed for $592.24 in the early 1990's. 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? Seems like they could have produced that part a lot cheaper as a straight pipe instead. But maybe because of the low production numbers, it was better for them to just use the empty housings for JDM models?
 
simple

simple

Active member
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.
 
9

93celicaconv

Member
simple":34oac83d said:
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.
Click to expand...
You are right, Simple, the MR2 uses the exact same part number for the manifold converter sub-assy. That is a good idea to check other vehicles that would have had the same engine in the same area for part commonality.
 
9

92RC

Member
Roreri":25cd2nj8 said:
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?
Click to expand...

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.

 
9

92RC

Member
93celicaconv":3mmwab7p said:
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?
Click to expand...

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)




ST185-0023348 is a 1992 BLMVZ model with the 25051-74020 https://bringatrailer.com/listing/1992- ... gt-four-2/
 
9

92RC

Member
simple":29izheio said:
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.
Click to expand...

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
 
9

92RC

Member
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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