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23

The main purpose of putting it right after the manifold is heat. The cat functions best when hot. Placing it as close as possible to the manifold helps the cat heat faster and stay hotter, which produces better results in what it's designed to do: curb exhaust emissions.


15

Cats can stop functioning in a couple of ways: physical deformation due to high temperatures According to this article, the catalyst melts at temperatures above 2100 °F (1200 °C). In the event of a meltdown, the catalyst gets permanently damaged, at which point it doesn't scrub the nastiness out of the exhaust gases and serves as a major exhaust ...


13

Even before a cat plugs, you can test your cat using a laser thermometer. You are looking to compare the inlet and outlet temps on your cat. Do the following: Run the engine up to operating temperature (at least ten minutes so the cat should be fully warm) Check and record the inlet temperature. You're looking to measure the temperature right where the pipe ...


13

A catalyst is a chemical that contributes in a chemical reaction but remains unchanged after the whole reaction is complete. In a catalytic converter platinum is the catalyst that converts unburned hydrocarbons into H2O and CO2. If there is too much unburned hydrocarbons going into the catalytic converter, it greatly increases the temperature inside the ...


13

tl dr: There would be no issues with the running of the vehicle. If the car in question is equipped with OBDII (or the international like), where the cat is being monitored by a second lambda sensor (O2 sensor), the only side effect of removing the cat would be the check engine light (CEL) would illuminate to show the secondary lambda issue. This would be ...


12

The lack of a heat shield is not an imminent hazard. You do want to take a few precautions. First do not park over any flammable objects such as grass, leaves trash etc. Don't place anything on the floor above the converter that may be damaged by the heat like a laptop, digital camera.


10

Looks like part of the muffler to me. You should have it replaced it could end up obstructing the exhaust.


8

It was indeed the catalytic converter (the EX does not have a pre-cat). After replacing it, the downstream sensor graph spends most of its time above 0.5 V, as it should if the converter is working. Update: I started getting this error code again, a little over a year after replacing the cat. I also finally found a guide on how to read these graphs, from ...


8

Most vehicles which are OBD-II compliant (newer vehicles are a little different) use just the O2 sensors located before the cat to adjust the air/fuel ratios. The in-cat or after-cat O2 sensors are just used to check the efficiency of the cat itself. Therefore, in most modern vehicles a car can run just fine without a cat. Please note, this is not to say ...


7

Looking at the description of the California O2 sensor for your car, the only thing different on it (besides the internals) is the electrical plug. The wrench which you tighten it down with is 7/8", which means the sensor bung should be the same size as well. I don't think there is any real external difference between the California and non-California sensor....


7

According to this website, the cat can surely be plugged by coolant entering the catalytic converter. Here are the reasons given on the website: Engine Tune-Up Required. A number of problems could occur to the catalytic converter as the result of an engine that is out of tune. Any time an engine is operating outside proper specifications, ...


7

This website seems to answer all of the questions you have asked above. http://www.easterncatalytic.com/education/tech-tips/proper-break-in-can-prevent-future-problems/ The website discusses proper procedures to make sure that the catalytic converter is broken in correctly. At the bottom of the article there are steps to break in the catalytic converter. ...


7

Picture 1 is the downstream 02 sensor. Upstream is located on the exhaust manifold. Picture 1 contains both convertors. Picture 2 is the exhaust resonator.


7

I suspect you diagnosed the situation correctly: that cat looks backwards. It’s a little hard to tell from the pictures but it looks like a straightforward manufacturing defect: the cylindrical section between the welds to the ball connectors appears to be reversed. You might be able to get a muffler shop to cut that section loose, reverse it and re-weld ...


6

In short: no. To pass smog in California (and other CARB adopting states) the catalytic converter must be the one from the dealership or one that is in the Aftermarket Catalytic Converter Database. The catalytic converter must be one of those listed for the Toyota Prius, but unfortunately there is none for the Prius. For now the only possibility is to try ...


6

A catalytic converter incorporates a structure that is coated in precious metals. When catalytic converters first came out that structure was ceramic balls coated in the metals. This didn't work so well and the structure was changed to either a honey comb or a monolith, both ceramic. The tubes of the honey comb run the length of the converter. A monolith is ...


6

All of this comes from: http://auto.howstuffworks.com/catalytic-converter2.htm Ok, attacking each of these in order: What exactly is a catalytic converter? It is a device in the exhaust path of your car that scrubs unwanted gases from the exhaust stream. How does it work? In chemistry, a catalyst speeds up a chemical reaction without actually taking ...


6

It looks like usually, catalytic converters, if totally undamaged and treated correctly, shouldn't die with age. The article you referenced says, The truth is, on modern vehicles, the catalytic converter should last the life of the car or truck, given an "average" life of about 100,000 miles (160,934 kilometers). However, this does not indicate how much ...


6

The concern is valid. Liquid coolant is not of particular concern when at ambient temperature. At higher temps the Phosphorous, used as a corrosion prevent agent in coolant, is a concern. It binds with the Cerium used as an Oxygen storage agent in the catalyst substrate to form CROP, Cerium Oxide Phosphorous. This makes the Cerium unavailable to passing ...


5

Just to add to the other answer as I ran into this same issue, what kind of emissions do I have on my mitsubishi galant? I had this code: P0421 and I had to replace my O2 Sensor & the catalytic converter but I wasn't sure if I needed the CARB (California Air Resource Board) compliant ones or not. There is a label that identifies what type you have. I ...


5

tl;dr: I can't find any evidence that removing the catalytic converters on this model will improve the car. It will definitely confuse the ECU (and obviously pollute more). I've looked hard for any dyno sheets that show any concrete evidence that cat delete alone will add power. Removing the cats is something that I would almost never recommend outside of ...


5

I can't tell you if it'd fail inspection or not, but there's a good reason for its existence. It's basically a heat shield that protects the body of the car and the carpet/sound deadening in the car from the heat of the cat. Catalytic converters can get very hot (in the worst case, glowing hot) and without the heat shield that can cause problems or at least ...


5

You should be fine. Though I would recommend unplugging the connector to fuel injector #7 to minimize the amount of unburnt fuel that makes its way to the catalytic converter.


5

If an exhaust restriction is suspected a pressure gauge pre-catatlyst works just fine. My maximum cutoff pressure is 1.25 psi but most good systems will be well below that. The intake manifold vacuum is also a good clue. If it is not close to the idle reading at 3000 rpm suspect an exhaust restriction. In the case of a restriction the vacuum reading will be ...


5

• Why does it need to operate within a certain chemical range? The gasoline engine catalyst feedgas (exhaust gasses) must remain in a very small window of fuel mixture because the chemical reactions the that reduce NOx and oxidize hydrocarbons are mixture dependent and mutually exclusive. NOx can only be reduced in a fuel rich environment and HC can only ...


5

If you have rattling on acceleration and the fuel economy is depressed, it is very likely that the catalytic converter core has cracked and it is blocking the exhaust now. You can try to measure its efficiency first by looking if the rear O2 sensor voltage reading after heating is steady (so the catalytic converter is good) or jumping (so it is bad). If it ...


5

Excellent graphs. The after catalyst sensor shows normal mixture readings. The PCM can and will operate the system lean or rich depending on operating conditions. The voltage will rarely be held at any intermediate voltage, such as 0.5 volt. This is an urban legend not based on engineering fact. The rear sensor voltage should remain steady at any steady ...


5

If you're not worried about the check engine light (which will more than likely turn on since the 02 sensor will be receiving an excess amount of exhaust reaching it now) or environmental considerations, then removing the cat won't cause any harm to your engine. Some people even believe that driving without a catalytic converter allows the engine to breathe ...


5

A lean burn won't necessarily ruin your catalytic converter. What it may do long before that happens (depending on how lean you're running) is burn the exhaust valves, piston crowns and overheat your engine. Fuel as much as being required to cause ignition also provides a crucial role in cooling the piston, cylinder and exhaust valves.


5

The monitors are usually run easily on this engine setup. The following pre-conditions must be met for running the monitor: Coolant temp above 176 deg F, Intake air temp above 14 deg F. No trouble codes set or pending. Replacing the catalyst will not affect the monitor. The monitor test runs whenever the right conditions are met regardless of catalyst ...


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