Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Catalytic Converter

Just so you know,

He has for a long time been host of a Car Talk show on a Houston TV show. He started as a mechanic at his grand-father’s Texaco 42 years ago. The link above includes at the bottom a link to his 36 Youtube Car fix videos. His e-mail address is available online.

One of those 36 videos includes the one on using cleaner to clean catalytic converters.

I stand corrected. At the bottom of the index page of videos is a “Load More” button.

I sent him an e-mail. The following answer which came within seconds proves his e-mail is valid.

“It’s summer vacation time. The wife is done teaching. Scotty is far
away from the computer until June 13th. any question asked will not be
responded to unless it is resent on June 13th or later.”

I will set an alarm to send it again as stated.

Any replies?

i wanna know if lacquer cleaning cat is for real! LoL

Go to Youtube,and search for Scott Kilmer. He has a radio car show in Houston, and this thread and other related ones, are based on his video which shows him putting lacquer thinner in his tank, and claims it cleans the cat.

He actually said that is second choice. First choice he says take it off the car if you can and toss it in a bucket of water with soap (laundry) over night, but they are hard to get off.

Most people, here and on the web say it will not work, but will harm your car’s fuel system. None of them have tried it.

I did a lot of Googling, and all those who actually tried it says it works. There aren’t many of them, though.

So I want to make it perfectly clear, if you try it and it harms your car, you get to keep all the broken pieces, no charge. In other words, if you try it, you take responsibility for what happens, good or bad, we do not.

I will eventually try it if my cat shows failure again. I now have my Equus 3140 scanner with me in Mexico. It started working all by itself. If it fails, I am going to try it, and if it does $2000 damage to my car, I will pay and not whine about it, because I will then know. I am a very curious person.

Some things I gotta’ do, just because. With all the insistence here it can’t work, 100% by people who haven’t tried it, my Irish stubbornness says I gotta’ try it, no matter what, though I will prefer to try it where parts are available, heh, heh.

A reminder, though. The dreaded P0420 code can, and often is, caused by other things.

Those oxygen sensors do get lazy after while, or do just plain go bad. I found a Subaru poster on a forum today, who said on Subarus it is almost always an oxygen sensor, not the cat.

The test does not actually measure the cat. It looks at gas ratios for exhaust coming into the cat, and compares it to the exhaust after going out. If the ratio falls lower than normal, they simply set the failure code for cat efficiency, P0420.

So, of course, if either sensor goes off normal behavior, it may show P0420 with a good cat.

It is generally recommended here to have a good mechanic, if you know one, check this out, rather than just laying out hundreds of dollars for a cat, to still have the same problem.

By the way, one person, just one, said a bad PCV valve could induce contamination to cause an apparent cat failure. Not verified by me.

Could someone, anyone, tell me what a normal reading is on a live data scanner, for the last O2 sensor, the one after the CAT? I am back in Cordoba, this time I kept it in high gear out of OD, and used the brakes.

My wife put the scanner where I could see it at a glance, when no cars were near me. (I am saying that to save the critics typing, over looking at a scanner while driving.)

Going downhill, which was a 17 mile trip for a 4,000 foot drop, the first two sensors ran 3.9 to 4.3, which is for very lean. And, S2 ran 0.000 all the way, which means gas turned all the way off. No cat failure this time. So, I wonder if the cool CAT last time absorbed a bit of pumped oil, will keep an eye on it.

Anyway, on flat ground, the S2, final sensor after CAT, runs 0.635 at 40 mph, and up to 0.750 at 70 mph.

The other two run around 3.3, with an EQ ratio like 0.992 and 0.997, which seems almost perfect.

This is what I’d like to know. Is that final reading S2 normal, for a good CAT, or is it normally lower? Any help would be appreciated.

I do like the live data feature, really lays a lot out for me. Glad I bought it.

As I understand it the first sensor’s signal should bounce up and down several times a second, much like a square wave, as the air/fuel mix swings from lean to rich.
The second (post converter) sensor should change much more slowly, as the converter behaves like an oxygen reservoir.
With a bad converter the second sensor will swing up and down too.
If the first sensor is "lazy"andchanges too slowly the second sensor can “keep up” and swing to similar to the first sensor, triggering a false P0420 code.

Since this is the first time I have had access to live-data, I have no idea how to tell what you are saying. It supplies nothing but a voltage reading which does change, but not fast.

That is why I am trying to find out what is a normal value. I am curious if the cat is already contaminated, and only needs a bit more to fail again, or if it is working great now.

Here is a useful article:

One of the issues you’ll likely face is just that scantools are generally too slow to really give a clear picture of the voltage changes.

That is a good page, thanks. I will look more at exactly what that scanner is doing when it looks at Sensor 2 back there. At this time, I will probably assume it is a little high, from a little contamination, and keep an eye on it. If and when it fails, I will decide what to do next.