NAC..'00 VW Passat 4Motion...$7200 in repairs!!!

[Tyson Varosyan]

***Here is the clear-up.
***

Not to be argumentative, or flamatory, but this post is way off. I don't
think posts like this should be left in the archive w/o a subsequent
post to help clear it up.

> Catalytic converters are a bunch of crap anyway! They do not work! Do what
> many people I know do on all their cars. Take a hole saw with a long
> extension, take out your cat, and drill the thing out. Or get a "Test
pipe"
> if there is one made for your car. Ether way, nuke the thing.

How is 'crap' defined? Is it because they can hurt performance? Or
because they don't improve emissions? Or because they have been eaten
and subsequently expelled by something? While cat. converters were a
significant exhaust restriction in mid 1970's cars, they are virtually
transparent in more modern vehicles. Unless you're trying to push
significantly more exhaust through a stock cat, hollowing it out won't
make any performance improvement. However, if you cat has melted, then
yes...it's a restriction. You may consider replacing it rather than
hollowing it out. In some cases, the induced turbulence of a 'hollowed'
cat can actually decrease performance of a vehicle.

*** "Crap" is defined by, "A part that has no meaningful purpose that
usually costs a lot and often does more harm than the intended good it was
supposed to provide." Newer cats are better than the old - true, but they
are still "crap". Over time deposits build up on the thin mesh inside
restricting flow. A slight bump on the cat from a bouncing rock or from
bottoming out on a speed bump can crush the damned thing causing serious
issues. Exhaust cannot get around it causing poor performance and horrid gas
mileage. They also make your engine sound wimpier as they work to take out
some of the deeper notes of the engine. Performance wise, yea, a brand new
cat may rob your motor 2% by my estimates. A 3000GT car I know did dyno a
6hp gain at the wheels after the replacement of a "newer" cat with a test
pipe. I will give you that, the chamber created by drilling out the cat, may
cause unwanted turbulence in the exhaust flow - hence I put in that bit
about the test pipe.
***


> A number of newer cars now have multiple O2 sensors, one before the cat
and
> another after. Unfortunately, our USDM car computers require an O2 input
to
> run properly, so you cannot do away with the buggers altogether. However,
> the O2 sensor that is located after the cat is usually only there to
monitor
> the cat and has nothing to do with fuel mixture. You can cut it out and
buy
> a $30 O2 emulator to keep the Computer, the EPA and your Check Engine
lights
> happy.

Every USDM new car since 1996 is required to have a pre and post cat O2
sensor. In *most* cases, the rear O2 sensor is just to tell the ECU that
the cats aren't functioning like they should. However, there's nothing
unfortunate about 'requiring' an O2 input to the ECU. While a modern car
will likely run just fine w/o any O2 feedback, it's also going to get
worse fuel economy, or produce more of the undesirable exhaust species.
Would you prefer your ECU to control the engine w/o any idea what the
results are? I suppose you could just pull the O2 sensor wiring and put
some black tape over the CEL. Maybe that's what we should recommend to
everyone who'd having problems passing emissions. <joking>

*** O2 sensors are not only not required, they are banned in Japan - the
country with highest environmental requirements in the civilized world. A
friend has a JDM motor running on a JDM ECU, the thing runs great and gets
the same or better mileage as my identical car on USDM specs - same exact
engine, same year, same car. Fact is, O2 sensors (excluding the wideband
variety, which are not installed stock on any cars I know of) are useless as
measuring devices and do more to confuse the ECU than to clean anything up.
Fact is, driving a few weeks on a failed O2 sensor you will burn more fuel
and put more junk in the air than the same O2 sensor will save over the
course of it's lifetime. Yes, if you have an aftermarket ECU, you are better
off running ether wideband O2 or none at all. I do agree, cutting out the O2
on a stock ECU is crazy - I've seen it done.
***

> Every car that I have seen without it's cat's shows better numbers on the
> emission tests than it did with them. Those things are bogus, much like O2
> sensors, and only work under certain conditions for certain problems in a
> lab. In the real world, when they malfunction, they will cause more harm
to
> your car and to the environment in a week than the benefits they
supposedly
> provided over a lifetime. Japan, the most environmentally conscious
country
> in the world, does not use cats or O2 sensors for just that reason.

I can think of very few cases where this would be true at all. What do
you consider better numbers? Have you actually seen any tests where
emissions improved after removing the cat? Catalytic converters aren't
just for lab situations. They are completely passive, and only require
reaching operating temperature to function continuously. O2 sensors also
work after only seconds of engine operation. They are used in all
conditions *except* high throttle acceleration (where a stoichiometric
mixture isn't necessarily desired). These conditions have little to do
with 'laboratory' environments.

Makes one wonder...if cat. converters *aren't* helping, why are we using
them? Maybe it's a conspiracy...the EPA has a LOT of extra platinum it
wants to cash in on to overthrow.....

*** Yes, I have seen it a number of times. Two track cars that I have worked
on heavily (which are street legal on paper to get from A to B) had shown
far better number than the previous 4 and 6 years of test results, after
having the cats removed. Yes, at all times the exhaust was nice and hot when
testing. An O2 sensor that still "works" but is a bit off, will wreck havoc
on your fuel mixture without it being obviously noticeable. A bad cat can
restrict exhaust flow forcing the engine to work harder and burn more gas,
which again is not obviously noticeable because it happens slowly over time.

Conspiracy? Yea, I buy that. Some fat cat that perhaps has a patent or a
manufacturing facility or both to make the cats, made sure to grease the
hands of the right politicians to get favorable laws for himself to make a
fortune with. And us suckers spending thousands more on every new car are
completely oblivious and do not question a thing. Best part - this is
America - buying politicians and getting BS laws passed is legal!
***

> Ohh and the partial reason that some cats cost so much is because the
> leading tips of the honeycombs are now made of Platinum.

Yep...they are now, and pretty much always have been. Platinum is one of
the more common catalysts. If they didn't have a catalyst, they would
just be called "unreactive honeycomb sections" and not catalytic
converters. :o)

***Good we agree on more than a few things :)
***