Natural gas smell?

What I'm saying is that the converter can cause poor performance. Yes, the engine originally caused the clogged cat. That happened before I got the car. Once that problem was fixed the cat had to be changed so the engine could breath.
The two cats I saw fall apart internally were from age. Neither cars had engine problems. One was a 76 Plymouth Duster that I owned. The clogged muffler was on a friend's Ford pickup. The honeycomb elements just broke apart over time.

 

Two way street... the engine kills the cat, but if the cat isn't replaced it can kill the engine.

 

I guess we need to wait til the OP gives us some more data.

 

Again, you cant make those statments without knowing how emissions systems in modern automobiles work. I would like to recommend you read the Cal BAR approved smog tech prep books i have, but they dont offer them for sale outside for those that pay to be in the certification courses. This one you can buy from ATG training, its fairly similar to mine:
http://atgtraining.com/product/advanced-drivability-diagnostic-strategies/

Your 1976 Plymouth Duster polluted the air more from it being parked than our Tacoma's do driving own the freeway at 65mph. Your mindset is outdated.

Please read this thread I made:
https://www.tacomaworld.com/threads/addressing-some-common-misnomers-of-the-p0420-code.396763/

Your catalytic is the last step in a complex emissions control system that is part of every vehicle made since the early 1980's. Your O2 sensor is the main and LAST input in a feedback system that governs the lean/rich ebb and flow of the fuel control system. Everything your engine management system does is in service to the function of the catalytic. The Catalytic has two sections, a oxidation and a reduction bed, made of platinum, rhodium, and palladium in differing sections to perform specific functions. The front area uses lean conditions to combine HC and excess O2 into CO2, the rear uses rich conditions to combine NOx and CO into H2O and N2. Nothing in your exhaust has ANYTHING to do with the function of the lean or rich conditions of the fuel management system. The O2 sensor simply reports on O2 content, nothing more. The downstream O2 sensor has ZERO effect on anything in your car other than the check engine light (as described in the above link).

The whole purpose of your ECU is to minimize emissions and maximize efficiency. A misfire is the most critical of all OBD codes because a misfire for any reason will dump unburnt HC though the exhaust, hitting the catalytic. HC when burnt, not combusted, result in carbon buildup. Carbon buildup on the honeycomb like media of a catalytic will lower flow and increase heat, as well as prevent the reactive elements form effectively changing the exhaust chemistry. Enough heat buildup will cause the media to break down and clog up the catalytic and/or your muffler. A catalytic converter that is installed and functioning properly has no control over the actions of your engine. The O2 sensor has only limited control over the fuel trims of the engine, nothing else.

Finally, your using a website called carsdirect.com, a portal for new and used car listings, as a source for technical expertise on engine management systems??????

Really?????? Thats like asking the part time checker at Home Depot how to build a house.

 

A clogged cat, regardless of cause, is going to cause performance issues. I'm done. Can we agree to disagree?

 

@Dirty Pool

 

Of course.

Not saying that its not the catalytic, just saying that it needs to be known why its happening before replacing parts.

 

Dang, I though curiosity killed the cat.

By the way, natural gas (Methane) is a colorless odorless gas. A substance called Mercaptan (Methanethiol)is added to aid in the detection of leaks.

http://www.independent.co.uk/news/uk/home-news/what-exactly-is-mercaptan-8462250.html

 

Would you acknowledge that the ECM play a role?

As the catalytic converter deteriorates, the ECM tries to compensate by changing ignition parameters.

 

Then tell me what the mechanism is for the catalytic to send and signal to the ECU. Or even tell me the sensor that measures exhaust pressure.

Ive laid out the facts of how your engine management system works. Youre trying to argue what came first, the chicken or the egg.

 

The egg must have come first. (rotten egg smell)

 

No not trying to say that at all. Only that the ECU play a role.

 

The point where the upstream O2 sensors screw into the exhaust is the last point of any input to the ECU. The downstream O2 sensors only trigger a CEL, and have no impact on ECU function. Yes, a clogged exhaust component will cause loss of power and a possible high HC/CO condition by restricting the throughput of fresh O2 into the combustion chamber.

Saying the catalytic is melted/damaged, so you need to replace it is the mindset you will get if you take your truck to the idiots at Pepboys to work on your car. Then you will be back in a month needing a new catalytic because your engine exhaust destroyed the new one.

The professional way to solve the problem is to find out why the catalytic is damaged. A catalytic does not just 'go bad' and clog up the exhaust unless the engine or owner does damage to them. A catalytic can stop effectively processing the chemical makeup of the exhaust and still flow perfectly fine. Not correcting people on here that think that way is only going to allow more bad information and thinking to propagate, costing us all more money and frustration in the end.

 

One thing that could have adversely affected the cats is a dirty litter box.

 

Awwwww fuuuuuck naw.

 

the previous owner dad battling a rough running engine. He brought to a shop and they replaced the following
Fuel pump (claims the pressure wasent up to spec)
Fuck filter
Maf sensor
Front O2
Cleaned throttle body
New spark plugs.

Runs great. Once in a while it will stall on start up but than I just fire up and it runs good.ill clear the code with my OTC scanner and it will come back on 30 miles later

 

Didn't know you had to replace Fuck Filters on this truck.

 

Haahahahaha my phone loves to auto correct lots of words with "fuck" I must use it to much

 

So can the rear O2 cause check engine light to come on and say catalytic Efficiency If the O2 is shot?