New Catalytic Converter

I have a 1998 Honda Civic EX Sedam. It has 209,800 miles as of now.

Recently, I had the heat shield for the cat. converter replaced, due t
the old one rattling. I felt that it may have been due to decay of th
cat. converter itself.

Is there a point to where a cat converter should be replaced, as a mean
of routine maintenance

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When you don't pass smog any more. And even then you don't replace it
unless diagnostics point to it needing replacement.

OEM cats last for galactic mileages if the engine is given decent care.

 

I personally would say if it lasts 200k+ miles and it then
fails emissions, then the engine may have been cared for
just fine. This is based on reading about others' cat
converter failures as well as my own recent experience
(failed NOx emissions at 206k miles).

Many sites say the cat is supposed to last the life of the
car. But what is the life of the car in miles and years? Are
those sites hearkening back to the days, not too long ago,
when a car that lasted 150k miles was a good one? Older cars
will have deteriorating parts not readily maintained. The
fuel/air mixture and its purity is more likely to be thrown
off, meaning it is more likely contaminants get into the
cat. Plus ISTM that the really old cars have seen a lot of
fillups. More fillups = more playing of the lottery that
impurities in the gas.

As for waiting until the car fails emissions, for a
ten-year-old car I would consider, among other things, how
the car's MPG is today versus five years ago. It is possible
the cat is clogged, raising exhaust back pressure, and
reducing MPG. I saw an improvement in MPG (over several
fillups) after replacing my 91 Civic's cat converter a few
months ago. The car may run noticeably better, too,
particularly under loads like long steep hills.

 

OEM Honda cats last well over 300,000 miles provided all the HT ignition
components are replaced at regular intervals (with OEM only) of five
years or less, the car is never allowed to even come close to run out of
gas, and the oil is changed every 5K or less.

Poor maintenance and aftermarket parts, plus running out of gas, are the
primary killers of catalytic converters.

Proper care must start from mile one and never, ever let up. Running out
of gas even once (or even regularly running with a very low fuel tank
level) will take a significant toll on cat life.

Gasoline impurities have nothing to do with cat life, unless you somehow
ended up with leaded gas at some point.

Cats only ever get clogged from poor maintenance, aftermarket ignition
parts, or oil burning (poor maintenance). A cat attached to an engine
maintained as I state above will never get clogged.

 

I can appreciate your confidence but I have seen nothing to
back up your claim. OEM Honda cats may last this long but I
think it is the rare one that does, even with good
maintenance.

Dirty unleaded gas may shorten cat converter life.

We disagree. Your opinion vs. mine.

 

It's good maintenance that's rare, not cats that last 300K with that good
maintenance.

Many believe their maintenance is "good", even when it's definitely not.
This affects their reportage, and thus the results web surfers see.

No way. Not at all. Not in any way, shape or form, any time. The EPA sees
to that with devastating penalties for transgressors.

As far as cats are concerned, retail road-going automotive gasoline in all
of North America is of superbly excellent quality, everywhere, all the
time. No exaggeration or exceptions.

Of course.

 

unfortunately, that's not true. there are most definitely different
qualities of gasoline, and different degrees to which they affect
catalysts. now, there is indeed a base enforced by the epa, but it's not
at a level that /ensures/ catalysts last forever. and "enforcement" is on
a batch basis. some batches are tested, most not. you don't /really/
know what you're putting in your tank every time, especially if you buy
discount.

 

This has been on my mind ever since I started reading more
intensively about cats a few months ago. It seems to me it
is really hard to say what the cause is of high mileage cats
going bad. You might be right. I just do not know and have
not seen any really good discussion of it. Only the vague
"should last the life of the car" seems to be most
everywhere.

One factor that is on my mind is that it seems almost
impossible to delay ring wear and so oil burning etc. in
older cars. So despite the best maintenance, the probability
that more oil and other crud is going out the exhaust is
better. Blah blah you know the rest. Does that mean one who
is really careful should count on 300k miles? I just do not
know. Getting data is particularly hard given how few keep a
car to 250k+ miles while also having ensured excellent
maintenance habits.

 

I take it they fail slowly?
Over the last few years, both my smog test HC counts have been creeping
up. At last August's test the idle was 1 (one!) count below spec. The
car runs fine and gets great mileage. Plugs, ignition hardware, etc.
have all been changed at least once during this interval.

I know this isn't much to go on, but does this sound like a slowly
failing cat? (92 Accord, I4, M5, 190K.)


Thanks

 

Yes.

It's usually "sintering" that causes them to deteriorate and lose
effectiveness.

/Way/ too hard to say from here. I'm thinking not. You need to give ALL
your numbers, not just the HC one. If you have a history, give that as
well, not just the numbers from one test.

Here's an example of a history:
http://www.tegger.com/hondafaq/misc/91_integra_emissions.html
I go for smog again this spring with likely over 320K on the odometer. Plus
my cat is now a new aftermarket unit (old one rusted out). This should be
interesting.

 

Here's all the history Az DOT has.

HC Idle HC Load CO Idle CO Load.
(220 ppm) (220 ppm) (1.2%) (1.2%)

2004 173 82 .34 .52
2005 181 74 .21 .46
2006 207 100 .56 .64
2007 219 105 .4 .46
2008 190 157 .6 .57


I use M1 5 or 10-30, and don't add any oil/fuel additives, so prompt
zinc poisoning seems somewhat unlikely. Car burns no oil to speak of,
needing a little over 1/2 qt at 3500~4000 miles. Oil gets changed after
another ~4K.

Wary of 2007's near miss, I made a real effort to heat the snot out of
the cat immediately before 2008's test. A week before, I threw in a
bottle of Valvoline 'synpower' injector cleaner ($2 at Big Lots!), which
supposedly has semi-useful phenolic amines in addition to the standard
kerosene and 'petroleum distillates.' Then made a point to rev and load
the lump on the way into work. Idle and low throttle smoothness did
seem to improve.

Mileage has been constant over the last 4 years, varying from low to
high 30's, depending on my driving. OEM temperature plugs look very
good, no sign of excess gas in the mix.

Thanks

-Moo

 

Numbers are incomplete. No NOx. No CO2.

Does AZ not test for NOx?

 

"Tegger" wrote

It's been many years since I've had to have a full test on my car, as I kept
buying new ones, and new ones are exempt from inspection. But seeing the
above HC and CO testing, that's about what I remember being tested. So I
suspect they don't test for NOx, though in reference to the catalytic
converter inspection (on the right side of this sheet) there is a notation
about NOx:

http://www.myazcar.com/pdf/emissions_control_equip.pdf

Note that this sheet is titled "Emissins Control Visual Inspection...." Our
state legislature never had much interest in education, you see.

 

I know they used to, but I've been outside the test area for 8 years. AZ
never reported CO2 but would fail the car if dilution was excessive.

The NOx would certainly complete the picture, but I'm thinking none of those
numbers - even in 2004 - are very good looking. The idle HC has been pretty
close to the limit from the beginning and not changing much. Ditto the CO
under load. (As I found out the hard way, the CO under load is also
sensitive to changes in load. My carbureted Dodge failed with 5% CO under
load because it had a feedback carb and the fuel pump was bad. Under
acceleration the carb went full rich trying to compensate and when they let
off the accelerator the pump caught up... blammo!) IIRC the car is a 92
Accord, so it was a dozen years old when the 2004 test was run. The CO idle
numbers make me suspect the O2 sensor has seen better days, and getting that
in line would probably clean up the picture (if not the numbers).

The HC numbers are also sensitive to engine temperature and even oil
condition. Some people report passing failed HC tests by changing the oil
and retesting. The engine temperature is supposed to be taken into account
by running a "conditioning cycle" (revving the engine) and retesting if the
test failed the first time, but that is not done if the test is passed the
first time.

Mike

 

LOL! When I moved to Arizona from California in 1874 I was immediately
struck by the lax standards for spelling even in public signs. There was a
cabinet that was prominently labeled "ELECTRICAL CABINENT" in front of the
building where I worked and there were street signs proclaiming the street
to be "Indain Trail." I lived on Wescott street and the signs were pretty
evenly divided on the spelling: Wescott or Westcott.

I was more amazed by the lax standards for auto safety. A fellow at work
wanted to register his VW beetle, and I didn't think it could be registered
until he added a headlight... one headlight was not only missing, there was
a big hole where the mount should have been. No problem!

Mike (Hey, y'all, holt my beer and watch this!)

 

"Michael Pardee" wrote

How'dja get here - by covered wagon?

Wail, I think the state's toughened up some aspects of the testing, but were
smart to realize that new cars aren't going to fail, so they've exempted
those that are up to 4 years old. But get this: Mine's now 5 years old and
just today went in for testing. But what did they test? They checked to see
that the car has a gas cap, the check engine light doesn't come on when the
engine is started, and that my OBD connector has "integrity." They did not,
um, sniff the tailpipe as they did on Glen's car.

All that for $12.25. I could have gotten a 16" pizza with mushrooms for that
money, and it'd have tasted a heck of a lot better.

 

Or 1974, whichever <8^P

 

Didn't they hook the OBD to their computer? What manner of 'integrity'
were they looking for?

Errrr... I'll let the tailpipe crack slide, but I gotta draw the line
at being called 'Glen!' That's low...

Ah, shrooms. That explains a lot!


Last I looked, Az doesn't conduct any sort of driver's test, either
written or on-road. Show up, pay your $, prove you can detect large
shapes with at least one eye, and you're golden. A license lasts for
something like 20 years. I can't fault the lean government, but you've
got to keep the lax standards in mind and drive very defensively.
Riding a motorcycle developed my sense of paranoia regarding traffic.
It's served me well in Tucson.

-Greg

 

"Greg Campbell" wrote

Sorry Greg! ;-) I was going on memory.... not very high integrity on my
part. As for the OCD/I mean OBD, I saw the tech hook something up to
something underneath the car's steering column.

Yum - and fresh, too.

I got a new license about 12 years ago, and yeah, it's good for another 4. I
guess 65 is a magic number. You're right -- I don't recall having had to
take a test even when I moved here, but 12 years ago I had to look into the
little magic viewer to identify colored things. I know "kids" in their 20's
have licenses that are good until they need walkers.

 

All right, assuming NOx and CO2 are unavailable, I can think of a few
things off the top of my head. This is in no particular order, so do the
easy, cheap stuff first.

Remember that HC is simply raw gas that's getting out of the combustion
chamber without having been burnt up first. CO is incomplete combustion,
from too much fuel and not enough oxygen (the resulting combusted
molecule has only one oxygen atom instead of two).

1) Check the cat inlet and outlet temperatures.
Take the car out for a drive sufficient to warm the engine up to full
operating temperature. A bit of high-speed driving is a good idea. When
measured with an infrared thermometer, the cat should have an outlet
about 30-100 F higher than the inlet. If in and out are the same, or the
outlet is cooler, the cat is either insufficiently warmed up, or it's no
longer working anymore.

2) Do you have EGR?
Partially-plugged EGR can cause across-the-board high emissions, which
is why I asked about NOx.

3) Retarded ignition timing.
You'd be dumping raw gas directly into the exhaust manifold, expecting
the cat to do the clean up, something it's not designed to do.

4) Dirty injectors with poor spray pattern.
Run a Motorvac service (~$100), which is not a bad idea even if there's
no actual issue to solve.

5) Thermostat too old and stuck open.
Will cause rich running and high emissions.

6) What do the spark plugs look like? What kind and color of deposits on
them? Do they show signs of proper spark? Have you checked each plug
wire to make sure you get a purply-blue spark at each one? (Use a spare
spark plug to check in a dark garage or at night.)

7) How old is the oxygen sensor? Is it OEM or aftermarket?
An old sensor will result in poor control of fuel mixture.