Catalytic Converter

[Travelover]

Another suggestion is to google "murano forum". You come back with something like this:

NISSAN MURANO . ORG - A Home to Nissan Murano Enthusiasts

I've found that certain vehicles tend to have certain problems and it helps to poll a group of owners with the same vehicle - just like we see here with tractors.

 

[ray66v]

Yes, I don't really hear much other than the typical cooling down noises it has always made.

So are you saying the cat could be damaged because of a recurrent misfire? I understand how that might happen but the diagnostics should indicate that as well I would think.

There should not be a lot of metallic cooling noises after a 5 minute drive. I have noticed lots of this metallic noise is a final warning of a failing converter.

Yes, you would normally expect the computer to notice misfiring. They do not always throw a code, until it happens often enough. A better diagnostic computer can find unreported misfires. I cannot imagine that a few misfires could cause converter failure, but I have seen a converter fail with almost no warning.

I know of a Malibu that had a converter failure without any codes. The only symptom was the car had developed a hesitation in the mid range of the throttle, and a slightly rough idle.

Three friends, who are also mechanics, suggested different causes, no one agreed with my diagnosis, which was based on the metallic noise theory. one week later, a red hot converter settled the debate.

 

[dfkrug]

Will look into aftermarket units. I knew they would less expensive but did not know by how much.

George, I have had very good experiences with cheapo generic cats from JCWhitney. In my custom car days, I would run cats to pass my smog test, then take them off.

For modern electronically controlled engines, no cat would likely not be good as one or more of the O2 sensors would be sending the wrong signals. Sometimes you can get rid of the "pre-cat", and run only one converter and have things run OK after warm-up.

I totally agree with TRAVELOVER. The enthusiast sites usually have tons of info useful for DIY repairs and modifications. I have been a heavy user.

 

[RonMar]

RonMar, do the O2 sensors provide any performance or durability benefit? I don't care if the check engine light stays on. What I'm getting at, is if I hollowed out or replaced the cat with a tube, will the abnormal readings from the O2 sensors cause any problems other than emissions problems and a check engine light?

In the case of the front and rear O2 sensors, the ECU is looking for a difference between the two under certain conditions. Without this difference, it throws a code to direct you to either an O2 sensor problem or a catalytic converter problem. If the cat gets rodded/bypassed, and with good O2 sensors, the vehicle should perform OK, but will probably show a code as it will be missing the differencs that the cat provides...