supraTT is correct. The dealer/manufacturer cannot reject a warranty claim because of mods unless they can demonstrate that the mod directly caused the failure in question.

And as I noted above,, there is NO WAY loose material in the exhaust system can flow upstream and enter the compustin chamber.

And there is NO LAW that says you cannot replace the OEM cat converter (or any other exhaust component) with a proper functioning one from an aftermarket supplier.

bill

 

The only reason they said this is because they were familiar with the problem on the Sentras as stated above. It is possible with the stock cats on the sentra because it has two cats inline one being very close to the exhaust manifold with a straight shot to the head.

It is very unlikely and improbable for this to happen with the stock or aftermarket cats on 350Z. They just found an easy excuse to give you based on your mods. I would have an outside mechanic take your cats off and take pictures to show that cats are intact. If they had broken apart you would know it. Then either put them back on or the stockers back on and return to dealership. As said above they have to provide you with proof that the modification caused the issue

 

As of January 1, 1988, all persons engaged in the business of automotive service and repair, as well as other parties named in section 203(a)(3) of the Clean Air Act*, are prohibited from installing or selling aftermarket catalytic converters which have not met the criteria of EPA's interim enforcement policy entitled 'Sale and Use of Aftermarket Catalytic Converters'* (published on August 5, 1986). The installation of non-complying converters by a named party will be considered a violation of section 203(a)(3) of the Clean Air Act, and the violator may be subject to a civil penalty of up to $25,000 for each improper installation.

When can I install an aftermarket converter?

There are only 3 situations when you can install an aftermarket converter.

They are:
(1) if the converter is missing from the vehicle when brought in for exhaust system repair;

(2) if a State or local inspection program has determined the existing converter has been lead poisoned, damaged, or otherwise needs replacement;

(3) if the vehicle is more than 5 years old or has more than 50,000 miles*
(8 years/80,000 miles for 1995 and newer vehicles) and a legitimate need for
replacement has been established and appropriately documented (e.g., a
plugged converter or unrepairable exhaust leaks).

Any other converter replacement must be with a 'certified' or new original equipment (OE) or equivalent converter. Aftermarket converters subject to the enforcement policy requirements cannot be used for replacement if:
(1) the existing converter is present and functioning properly; or
(2) the replacement is under recall or warranty; or
(3) the vehicle is returning from overseas use.

 

Sorry Folks, Catalytic Converter breakdown (whether it is caused by dropping, over fueling, or other method) can feed back into the cylinder under reversion. This will then make mince meat of the Piston Rings.

Is it common? No
Is it possible? Yes
Is it likely? No
But the consumer in this case is protected as it can be tested whether the Cat was the cause of the failure. In which case he can approach the manufacturer of the cat for coverage since converters are supposed to function for a minimum poeriod (Exact time I do not know).

Remember Exhaust works in pulses it is not a constant flow.

 

An engine backfire is the only conceivable way I can think of where a car's exhaust pressure would exceed the exhaust pressure of combustion..

 

Read carefully. I cant speak for other mfgs but we use aftermarket cats which are APPROVED by the EPA. It is true that there are certain conditions which make it completely legit, but as long as what you are replacing them with are approved its hard to build a case against it. Now my car has 61K miles so I am in the clear. I replaced mine at about 20K miles, but they were damaged by road debris at that time.

Now see how easy that was.

 

Sneaky bastard...

I was really just pointing out that there are in fact laws regarding catalytic converters(because it was stated otherwise). Not that we should follow them or anything. We don't have emissions testing in my state, much less vehicle inspections.

 

I had the owner of craford Z car call the nissan dealer, and tell them they are full of ****, lol... There is just no way that particles from the cat would get sucked in, instead of out. Thats just how i feel about this, and I totally agree

 

Your opinion, and you have a right to express it, is bunk. The cats DO break up, exhaust gases DO get sucked back into the head when you close the throttle, and damage just like that described here, DOES occur. Hopefully, you will get some good advice before expressing your ignorance to the dealeshsip - you will lose. As stated so tactfully above, you broke the law, you have now admitted it, and your technical knowledge of internal combustion engines does not quite measure up to Nissan. Sorry Charlie. Hear those that know a little more than you, like JuJube and Q45Tech, and take note if you want to have ANY chance of not getting a$$ raped in this case.

 

"...exhaust gases DO get sucked back into the head when you close the throttle, ..."

Absolutely impossible. The only time the exhaust valves are open is when hot, pressurized exhaust gasses are being discharged from the combusion chamber. Exhaust gasses/downstream debris cannot backflow into the cylinder.

bill

bill

 

"...prohibited from installing or selling aftermarket catalytic converters which have not met the criteria of EPA's interim enforcement policy "

"...a proper functioning one from an aftermarket supplier."

A proper functioning one will meed the EPA criteria.

Perhaps my post would have been more accurate if I had used the phrase, "meets EPA criteri", instead of "proper functioning.

Good research, BTW. But a link to the source would have been even more helpful.

But the legality of his modification is not the issue. It did not/could not cause the failure that he has described. They cannot deny warrenty coverage as the result of a modification that did not cause the failure.

bill

 

The comment "I reject your reality and substitute my own" comes to mind when reading these "it's impossible" replies.


Sorry Baily bill, it is a reality.

What Is Exhaust Reversion?



Exhaust reversion is the unwanted reversal of the exhaust gas flow backward into the cylinder during the exhaust stroke. There are several theories with regard to what causes exhaust reversion, and one held by Reher-Morrison goes like this: The exhaust gases burst into the header tube and then create a region of very high pressure. Similar to a compressed spring, the gases uncoil in both directions. Some of the exhaust gases travel backward into the port, and ultimately back into the cylinder. What’s the point? You can control exhaust reversion with a header-tube diameter that’s larger than the port (don’t port match the exhaust exactly to the header size). Additionally, quality valve springs are a must since they help to control the valves (valve bounce) which is also a contributor to reversion.

 

Assuming your quoted theory is correct how do you explain that after this "uncoiling" which the theory say's occurs in the header(s) and which drives the gases in two directions (toward the engine and out the exhaust) would carry cat material which are downstream from the headers into the engine..Theory's without empirical evidence don't make it so!! Any evidence to offer??

 

And just how do the "uncoiling" gasses overcome the greater pressure of combustion gasses exiting the exhaust valve?


Once again, how about a source, so the reader can have access to all of the material that might be available there? And so the reader can evaluate the reliability of the source.

bill

 

I ahve an VQ at the moment that was run too lean, melted the cat/s and inhaled the particles.. engine looks like its had grinding paste through it.
Have had similar experience with a RB26 that had a ceramic turbine wheel fail and sucked it back into the engine.
Reversion is a powerfull thing.. it will and DOES happen.

 

It seems like some people just don't have the sense to listen, research and evaluate. The man came here asking for advice on whether Nissan was BS'ing him. He got it. Believe what you will. The specV boards are full of threads on cat material inhalation, and that's just one vehicle. Google it.

 

It is not impossible. I had a friend with a early 90's Toyota pickup that was running too lean, and it burned the cats and the bits got sucked back into the combustion chambers. Bye Bye engine. the cylinders were trashed from all the scraping.

The back suction occurs when you are running near full RPM, and then you slam the throttle closed (like when shifting), and this momentarily causes the pressure in the exhaust system to be higher than in the combustion chamber. The gas will flow out of the exhaust system in both directions, one out your tail-pipe, and the other way back into your combustion chamber. It is this short instant of back flow that causes the particles to get sucked into the engine.

This is pretty common car tech knowlegde folks... Im suprised so many people here are claiming that it is impossible.

 

I gave you the name of the problem, and a quote. Why don't you take that and research it.

I have nothing to prove. I am simply helping the guy that asked a question and tried to point him in the right direction showing him that this can happen.

Just because you can't accept the fact that reversion is very real, doesn't mean I am required to research the fact that it exists for you.

 

two words: test pipes.

 

LOL.. I like that RevLimitZ.. Prob would have been a better choice