Restoring old catalytic converter's efficiency (cleaning method)

[RustyLugNut]

I have used it several times in the past with success. I mentioned this in other threads on the topic.

The most dramatic was a 2007 Dodge Caliber 2.4 L with a very expensive "Mani-verter" that had been coked up when a failed upstream O2 sensor and a ditzy wife conspired to leave a cracked and smokey exhaust system just a month from the strict bi-annual emissions test after she drove around for weeks with an engine light on. I TIG welded the cracks in the stainless housing and followed the mild acid wash process with the only change being an initial washout with "Purple Cleaner". This caustic cleaner removed the majority of the carbon coking. The mild acid mix concentration should be closely followed as a stronger acid reaction will strip away some of your precious metal loading in the converter.

The vehicle has an upstream and downstream O2 sensor and an algorithm to check converter efficiency by comparing the two sensor outputs. It also has test cycles the CPU runs periodically by pulsing the fuel mix rich and lean in a coded sequence with expected reactions from the O2 sensor compared to the actual. This prevents a simple O2 sensor defeat device on the downstream side allowing such shenanigans as cored out cats or straight pipes.

The factory mani-verter was eventually replaced with an improved aftermarket unit, but the cleaned converter did run for several years after the cleaning process.

[California98Civic]

Thanks for your experience. Yeah, I have seen a few testimonials. My test was supposed to give us readings A/B, direct from CARB that could show us how effective it is (or isn't). But as I explained above, the CARB gods were not smiling on me. So no test. I posted the process I used for others to consider. Careful critical reading is always expected/welcome. Thanks!

[cajunfj40]

Hello California98Civic,
Huh, the paper you linked is interesting - seems like a workable idea. The whole thing is available on ResearchGate as a pdf. Bummer on the no re-test. Did you happen to keep your old smog results over the years before cleaning, to see the degradation over time? If so, you can still get some information by comparing the next few smog test results after the cleaning process to see if there's a change in the downward slope angle, or if the slope moved higher, indicating either it is working better or worse or degrading at a slower or faster rate. True, you won't have an immediate A/B test result, but you can look at the trend over time. More variables in play - state of the test equipment, what it's baseline setting was, etc. - but better than no result at all.

Poking around, I found an older thread by BamZipPow here: Catalytic converter cleaning would you do it?

He noted that he'd cleaned his 380,000 mile T100 converter and put 41,000 more miles on it after that - but I can't tell if he had any code differences before or after. BamZipPow, you reading this? Do you have any info on whether the cleaning was effective or not in your application, like a code going away/staying away longer or smog test results?

I'm looking for a way to clean an O2 sensor - it would seem that similar deposits would be to blame, and it is also a ceramic-based device, so maybe this method could also be used for them. Google is useless - the most cited method is to soak the whole thing in gasoline. Yeah, no. Second is to heat it with a torch to cherry red and dip in water to get the carbon to flake off. Seems to me that would shatter the ceramic. O2 sensors are not that expensive, though, so it may not be worth it - especially here in the rust belt where it might bust off trying to remove it in the first place. My guess is that my rear O2 sensor has bad wiring or is totally gunked over from the outside with oil sludge from the leaks over the years - it reads 0.0V all the time. Pain to get to, have to yank the center console and remove a panel to get to the top of the transmission from the inside of the truck to reach the plug.

BTW, there are a number of patents around for systems using the solution to clean catalysts, like this one for hooking up via the O2 sensor bungs to clean them in situ: US8888921

[California98Civic]

Interesting information. Thanks. I think you are correct that there may be some utility in the next test, even though there will have been a two year gap. But it just won't be as cool as A/B one day to the next. Oh, well. As far as "results" in the second vid I posted in the #1 post, at minute 7:39 the guy shares his evidence, which amounts to a code going away when he resets the computer and not returning. Not a bad data point for homebody garage job.

[freebeard]

This is a timely subject for me as I now own a car with a catalytic converter. I chose to look into new prices:

https://www.carid.com/1979-volkswage...ic-converters/

They range from $48 to over $300. Any idea what makes the difference? For instance:

Kooks®
Green Ultra High Universal Fit Catalytic Converter # 350072377
Universal Green Ultra High Catalytic Converter by Kooks®. Emissions: EPA compliant. Converter Configuration: Universal Fit. This product is made of high-quality materials to serve you for years to come. Designed using...
Handles Exhaust Temperatures up to 1500FEliminates Emissions Related "Check Engine Light" (90% Success Rate)
$353.24 - $379.49

vs

Kooks®
Race High Flow Universal Fit Catalytic Converter # 350072381
Universal Race High Flow Catalytic Converter by Kooks®. Emissions: EPA compliant. Converter Configuration: Universal Fit. This product is made of high-quality materials to serve you for years to come. Designed using...
Handles Exhaust Temperatures up to 1500FEliminates Emissions Related "Check Engine Light" (90% Success Rate)
$136.81 - $142.41

What I take away is that "Green Ultra High" is twice as expensive as "Race High Flow" though the descriptions are identical.

Kooks! Heh. I should take it to Goofy's Muffler Customs to have it installed (Kidding, I'll flush it first).

I didn't find it but thesamba had a post on replacing the activated charcoal in a charcoal canister (such as my Superbeetle has) using material from a $14 Cadillac part.

[California98Civic]

I read about the price differences a little when I was planning to do the cleaning. IIRC, I think a primary source of cost difference will likely be the amount of catalyst metals and therefore the long-term durability. Cutting back on the pricey metals would cut costs. In the short term both CATs will work fine, but the cheaper one will fail first. (Also, probably they save on labor in their supply chain through unsafe mines some sweatshop somewhere in the world.)

That's one reason I chose to clean (the OEM Honda CAT is 19 years old and still puffin' passable gasses!).

Oh... I forgot to reply to this part of cajunfj40's message:

Originally Posted by cajunfj40

Hello California98Civic,
... Bummer on the no re-test. Did you happen to keep your old smog results over the years before cleaning, to see the degradation over time? If so, you can still get some information by comparing the next few smog test results after the cleaning process to see if there's a change in the downward slope angle, or if the slope moved higher, indicating either it is working better or worse or degrading at a slower or faster rate. True, you won't have an immediate A/B test result, but you can look at the trend over time. More variables in play - state of the test equipment, what it's baseline setting was, etc. - but better than no result at all. ...

Yes, I did save them. And yes, I will be very interested to see the change (if any) good or bad and post here!

[Xist]

I need to check out my cat. I read the best way to wash one was to throw it in the toilet, sit on the lid, and flush, but I am not sure how reliable "Dog" is. I drove to Mom's house and had a CEL when I was leaving her town. My bluetooth reader is in my Civic, which had been showing a code approximately once a month.

I never saw one in the Accord.

Finding somewhere open in sleepy small towns on Sunday took a while. The guy at O'Reilly said both of my catalytic converters were failing, but I failed to get the codes. I keep seeing P0420, but I have not been able to find out how many converters my car has.

I have heard of cats that sound like cans of marbles, ones that simply fall apart, and presumably ones that clog.

There are periodic nagging voices asking why they failed, the new one may fail also. Eric the Car Guy says Hondas and Toyotas do not like aftermarket cats.

This guy had a different method of cleaning it, which did not work:

https://www.youtube.com/watch?v=L_QIRFUg8K0

Mining.com, Hackaday, and Gizmodo each have articles about mining highways, but Cody's Lab tried it:

https://www.youtube.com/watch?v=v5GPWJPLcHg

People kept asking if he was going to keep sweeping the highway.

I asked if he was going to get a job driving a street sweeper.

[freebeard]

I need to check out my cat. I read the best way to wash one was to throw it in the toilet, sit on the lid, and flush...

Thanks. I didn't realize how much I needed to hear that again.

[California98Civic]

So the video proves we could mine... wherever the street cleaners have been dumping their catch daily for the last 40 years and derive precious metals. The dump? Futures of mining!

As for your accord and the cat troubles... I don't think a 2.3L inline 4 is likely to have two cats, do you? Pop the hood and look. The six cylinder was years later, I thought.

Toilets will not help you with this problem. Save them for their primary design purpose.



james

[Xist]

The first V6 Accord was the 1995 model. I was finally able to pull up a parts diagram and it showed two different cats for the same part on the diagram, but I could not find a difference besides price, which is significant

One dealership only shows the KL cat for $1,256.95. I could purchase another Accord for that price! Majestic sells it for $461.45, plus a $150.00 core charge, $35.58 shipping, and $3.95 handling. Total: $650.98. I put in my VIN, so hopefully that is the right part. Do I need to pay for shipping to get the core charge back? It would be worth trying to find someone that would pay more for it, but I still need to see what is actually wrong with my my cat.

Jerry Seinfeld once had a bit about flushing a toilet and having the water flow up. That sounds preferable to my new place where the water simply flows around that which I am attempting to flush.

We need Al Bundy's toilet!