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Catalytic Converter Cleaning Techniques

2K views 25 replies 8 participants last post by  PeteD 
#1 ·
What have you used to try to clean cats? did it work or not work?
I see Cataclean, Dura-lube cat cleaner, CRC 'guaranteed to pass', et al / etc... I have heard lacquer thinner mixed with gas in some ratio may clean a cat...
What is in cataclean?

So the vehicle in question is not an s10... on an s10 I would probably just replace the cats and be done since they are easy to get to and cheap enough...
but on some vehicles the cats are very difficult to get to, such as the vehicle in question. The vehicle in question throws p0420 and p0430 (cat below efficiency bank 1, cat below efficiency bank 2) and the cats have likely been poisoned a handful of times over the years because ignition problems are extremely hard to diagnose on the vehicle in question. with new ignition parts It is difficult to get it to run without missing when the motor is below 50 degrees and especially difficult with a cold motor in very cold weather. once it gets warmed up ever so slightly it runs fine. the downstream o2 sensors have been replaced with new oem sensors but the upstream sensors are the originals with 130k because they are so difficult to get to, like the cat.

i have new cats and upstream sensors ready to install but sadly its so much work to get to them and the risk of mucking something up and having the vehicle go down for an extended period necessitates the need to dump $25 mystery juice into the fuel tank with a wish and a prayer... just wondering which cat cleaners the fine folks here have tried
thanks
 
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#2 ·
These products are generally proprietary (or patented) solvent(s) that reduce carbon buildup in the vehicle's engine & fuel system. If there is excessive carbon build-up, the cause needs to be found and corrected to prevent recurrence. At best, the cleaners are a temporary 'solution' that treats the symptom(s), and not the main issue. And, that is specifically why I don't use them. There can be multiple reasons a cat fails - here's a link that summarizes common issues: Why a Catalytic Converter Fails

The best answer for a specific product's composition (if not on the label of the product) would be to contact the manufacturer directly. While they might be of some (questionable) value, I seriously doubt they will 'cure' a high mileage or heavily compromised cat converter. You could try one of these elixirs, as they claim there is no harm to the system, but I wouldn't anticipate any stupendous results. IF you're certain that the cat is bad, it is most likely in need of replacement (after resolving the problem that caused it to fail).
 
#3 ·
right on, yeah the cats were likely spoiled 2x during ignition problem diagnostics over the years. the motor in question has a really bad design when it comes to ignition maintenance. my goal with the magic cat cleaner potions is just to make it easier to start thru cold winter temps (as described in the OP) til i can have enough time and warmer temps to mess with it and run the risk of rounding off exhaust bolts when i swap the cats. theres no room on this model for cutting or welding near the cat so the options are limited and a simple job can spiral out of control quick.
the good news is, nobody in their right mind is trying to steal the giant cats off it and they are worth a pretty penny at the scrap yard...
oh and i found the new cats, the high end magnaflow model, on a price error for 99% off the 2018 prices =]

kinda venturing off on a tangent, i hope to actually keep this thread limited to cat cleaning techniques only. i imagine theres some cat lovers and emission test state people in here who have potentially tried a cat cleaning potion or two...
 
#5 ·
drive to your local exhaust shop and $200 bucks and an hour or so later drive away.
no need to try something to do something to something you already know wont work..
cheapest legit shop thats been around for a few years quoted it at $900 per bank to use my parts and that was maybe because i halfway know the original owner of that shop... and that was 2 or 3 yrs ago so i can only imagine its higher now. its dual exhaust and its way up in a slot with zero access and 18yrs of heat cycling and rusty fasteners. plus they want to keep the cat if they touch it... its some kind of law that they keep the cats. i dunno how much the cats are worth but i know they are oem jaguar and huge... $4000 a piece for oem new ones last i checked years ago... plus the vehicle has other potential money-pit-tier problems so theres plenty incentive to diy it in this case.

its worth trying a $25 mystery potion in this case for certain... its just a question of which one and finding someone who has tried some first hand...
 
#8 ·
i have started descending into the depths of the internet on this topic..
i am seeing claims, mostly regarding cataclean, that one bottle turns off the p0420/p0430 for approximately 800 miles. in my experience, the first 100 miles after a code clear/battery reset the light for p0420/p0430 may not come on anyways in my vehicle. reports seem about 50/50 that the vehicle passes emissions tests then the light comes back on with cataclean. customer generally seems happy it worked for that purpose.

I am wondering now if a bottle will help my cold starts for 800 miles because that may well be worth it for $25 til it warms up proper... i have no emission tests and actually replaced the ignition parts that likely spoiled the cat in the first place
 
#11 ·
i am leaning towards dumping some lacquer thinner into the fuel tank... scotty kilmer says its good... =/
i really dont want to but it needs somethin...
i think i am going to try it with like a pint of lacquer thinner and a few gallons of fuel. run it at 2500 rpm and see what happens. apparently lacquer thinner is bad for plastics though...
scotty says a gallon of lacquer thinner with half a tank of fuel... im not gonna 'half *' it, im gonna 'quarter *' it
the cats run at 850 degrees F when fully warmed. seems normal to me. fuel trims are in the -3 to +3 range.
basically it misses at initial start and throws cat low efficiency codes. once warm its fine and dandy...
 
#12 ·
i am leaning towards dumping some lacquer thinner into the fuel tank... scotty kilmer says its good... =/
i really dont want to but it needs somethin...
Well, geez, if Scotty the guru says so....it must be swell.
i really dont want to but it needs somethin...
Just be aware than due to the primary components (acetone, methanol, & toluene) in lacquer thinner, you run a high risk of creating more problems (damage) than you are trying to "solve." The off the shelf "mystery juices" might be a more benign approach, since you sound intent on heading down that path. Best solution - just replace it and be done with it.
 
#14 ·
well i rolled the dice...
cleared codes, drove 20 miles, some codes returned.
so with about 1/4 tank of primo fuel (vehicle calls for it), about half a gallon of klean strip lacquer thinner from walmart ($20.98), 75 miles of split highway/city driving with probably more WOT than most people are able to do safely, extensive idling and 2500 rpm holds while in park, all in the course of an hour thirty when the tank went dry. filled her up 90% with primo fuell, drove ten miles, done.
result?
I honestly dont know. people were reporting 'more hp' with lacquer thinner... i call placebo on that claim. i couldnt tell if the smoke out the pipe was normal or not. i have no clue if any damage was caused. light hasnt come back. we shall see.
 
#15 ·
well heres an update...
cat efficiency codes p0420 and p0430 have not yet come back and they certainly would have otherwise... cat checks say 'complete'. so far, i would say lacquer thinner in the fuel as described above may help get you thru a vehicle inspection. it certainly would have passed a 'is the checklight on?' exam.

unfortunately my severely rough idle during cold startups is still present. i checked the scanner and it was calling for 40-50% extra fuel on each bank about until the temp gauge starts moving off 'cold' ... i know the valve cover gaskets have a decent leak. and theres some sort of evap hose thats looking a bit crumbly... ... not sure what else would be causing it to throw so much fuel at itself only when it is cold starting...
 
#16 ·
update: one bank threw the cat code today. approx 200 miles after clearing it. the cat monitors showed green/complete in that time without the code set or light illuminated

i think it is likely related to the cold start issue because it popped on one bank that had a commanded fuel surge of 50% on a cold start. the other bank did not get that same surge and didnt pop the code.

so i dont know ultimately if the lacquer thinner did or didnt do anything but it seems as if it likely did clean the cats briefly and may just help you pass emissions checks til you can get a better cat on it or whatever
 
#17 ·
a few notes about my experiment:

'most people' say to run 'half a tank' with one gallon of lacquer thinner : i halved both #s

they also say to drive highway only for like 150 miles: i split my 75 miles between city/highway/2500rpm in park and as a result my cat didnt get as hot for as long of periods. i vaguely monitored cat temps and the cats get and stay at least 400 degrees hotter on the highway when youre just straight cruising vs city driving/normal idling and those temps swing quickly and dramatically. so a longer highway trip may work better.

also i did this in i believe under 2 hrs. i filled up with gas immediately after and drove some more to push all the lacquer thinner out of the system asap because it can dicker up rubber and plastic seals quickly if you let it sit
 
#24 ·
there is no emission testing here, the exhaust does not stink, the cats are not melted or restricted.
the cats and the upstream o2s are in barely accessible channels and bolted to the manifolds. theres room for extensions/sockets/impacts and thats it. no saws/welders/torches will fit up in there. so if i muck the 18yr old, heat cycled, rust belt bolts i am probably going to have to drop the whole exhaust instead of 'just' half of the exhaust... i dont have a lift and the one i normally have access to is recently sold.

the exhaust shops want more than the vehicle is worth and they aint wrong to ask it. im only shooting 5/8 on successfully loosening the bolts at scrapyards.

the check light doesnt bother me enough to use the defouler trick on the downstream sensors.
the backyard chemist and amateur jeweler in me wants to learn to clean and harvest the platinum
the amateur mechanic in me wants to learn to clean cats and install a pcv catch can to stop the vehicle from * on itself in the first place. the pcv on this motor was recalled, fwiw.
as much of a crappy design as it is, rest assured no one in their right mind is ever stealing these cats...

if nobody here has done it then nobody here has done it. if nobody here is interested then nobody here is interested.
 
#25 · (Edited)
well for anyone keeping score, ive got over 1000mi on her now. the one bank hasnt popped the code again at all. the code is still coming and going on the other bank. the monitor seems to factor in the last handful of drivecycles into the code equation and the unresolved cold start fuel trim problem is enough to keep the code lit every few days. the car runs fine once warm but has a distinct problem on cold starts that is even worse on cold days... the effects of which poison the cat for a short 2 minute spell until its warm enough and the fuel trims straighten out.
i am debating drilling a hole in front of the bad banks cat to spray some carb cleaner or lacquer thinner in every week or so at night til i can figure out the cold start fuel issue ... it might be less work in the long run... its total hack-tier but it beats a costly jaguar dealer trip. come mid march its warm enough not to matter anymore until mid november... the cold start fuel problem is a non-issue in warmer weather.

i saw some guy claim carb cleaner soaking in the cat overnight was beneficial in lightly cleaning it... we shall see.
 
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