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If P0420 is present then:
Topic Started: Apr 4 2012, 08:44 PM (5,280 Views)
iBLKBRY
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dayle1960
Apr 6 2012, 08:59 PM
Ok, so now we are getting into the theory side of my quest.

If the cat was plugged, then the rear O2 sensor would be pinging a P0420 because it would not be within a certain range that is required by the front O2 sensor.

Since my cat is not plugged, then I am wondering why both O2 sensors I have put into my downstream bung have thrown code P0420.

All I can think of is maybe the upstream O2 sensor is bad which is causing the rear O2 sensor to try to find the "sweet spot" and since the downstream O2 sensor can't find it, the dpwmstream sensor throws a code.

OR

My cats' honeycombs have a contaminating coating which does not allow the catalyst to do its job and thus the rear O2 sensor is suppose to sense particulates which are not being produced due to the contamination.

OR

My engine is exhausting something that the front and rear O2 sensors do not like.


So in review, I think the possible causes are

1. Plugged cat
2. Contaminated cat
3. Bad rear O2 sensor
4. Bad ECU
5. Engine spewing bad particulates which the rear O2 sensor does not like
6. Possible bad rear and front O2 sensors

What do you guys think? I'd really like to track this gremlin down and come up with a definitive answer.
What indication are you reading from your rear O2 sensor?
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dayle1960
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Fastest Hampster EVER

A CEL light on the cluster and when I plug in my scan gauge DTC P0420 is present
That is all of the information that o have. O have not taken it to a shop on put it on their computer.

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dayle1960
Apr 12 2012, 06:56 AM
A CEL light on the cluster and when I plug in my scan gauge DTC P0420 is present
That is all of the information that o have. O have not taken it to a shop on put it on their computer.

You're going to have to put this test on the road or a chasis dynamometer, boss. An Ultra-Gauge will give you some sort of a reading of the O2 sensors, although not of mwebb graphic quality. Somewhere in the FSM, this is mentioned.
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ascensions
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Je conduis une petite voiture.

mwebb
Apr 11 2012, 10:08 PM

but no
correct answer is , cold water
which is an exhaust by product

N2 H20 and C02 in a perfect world

will touch the rear 02 sensor thimble and if the 02 sensor heater is "on" the thimble will
crack from thermal shock , so Mr ECM does not allow the rear 02 heater to switch on until the water in the exhaust is hot vapor
First you say you don't know, now you have an answer?

You're correct, that water-vapor is a by product of the catalytic converter, but it's in a gaseous form. It would only turn into "water" upon condensation (cold air, etc), not a hot 02 sensor.

I'm willing to listen to alternate ideas, but a citation is needed.

To cite my previous response, the temperature required before catalytic converters reach their light-off stage is google-able:

Quote:
 
The average light off temperature at which the catalytic converter begins to function ranges from 400 to 600 degrees F


There's a great peer journal article here.

Quote:
 
The temperature and reaction rate increase dramatically at this point and the converter "lights off".
Edited by ascensions, Apr 12 2012, 07:51 AM.
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You haven't been truly chastised by mwebb until he calls you a Flatlander, or informs you that you're using the wrong kind of engine oil. :D :popcorn :lol

:cheers

https://www.google.com/#hl=en&sclient=psy-ab&q=site:geometroforum.com+mwebb+flatlander&oq=site:geometroforum.com+mwebb+flatlander&aq=f&aqi=&aql=&gs_l=serp.3...41089l42661l1l42851l10l7l0l0l0l0l541l2133l0j1j0j3j1j1l6l0.llsin.&psj=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=c98d3a4d2852b109&biw=1024&bih=630

https://www.google.com/#hl=en&sclient=psy-ab&q=site:geometroforum.com+mwebb+schnit+dog+oil&oq=site:geometroforum.com+mwebb+schnit+dog+oil&aq=f&aqi=&aql=&gs_l=serp.12...0l0l1l17846l0l0l0l0l0l0l0l0ll0l0.llsin.&psj=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=c98d3a4d2852b109&biw=1024&bih=630

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mwebb
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FOG

ascensions
Apr 12 2012, 07:51 AM
mwebb
Apr 11 2012, 10:08 PM

but no
correct answer is , cold water
which is an exhaust by product

N2 H20 and C02 in a perfect world

will touch the rear 02 sensor thimble and if the 02 sensor heater is "on" the thimble will
crack from thermal shock , so Mr ECM does not allow the rear 02 heater to switch on until the water in the exhaust is hot vapor
First you say you don't know, now you have an answer?

You're correct, that water-vapor is a by product of the catalytic converter, but it's in a gaseous form. It would only turn into "water" upon condensation (cold air, etc), not a hot 02 sensor.

I'm willing to listen to alternate ideas, but a citation is needed.

To cite my previous response, the temperature required before catalytic converters reach their light-off stage is google-able:

Quote:
 
The average light off temperature at which the catalytic converter begins to function ranges from 400 to 600 degrees F


There's a great peer journal article here.

Quote:
 
The temperature and reaction rate increase dramatically at this point and the converter "lights off".
i never said i did not know
i said "who knows who cares ..." because the real answer is not needed to test the system by those who do not have scopes and or scan tools that can display the relevant data .

the geo metro / suzuki ECM has no way to know exhaust temp
so
those wise engineers that programmed it assumed by 50 mph the exhaust gases would be hot enough so that there would not be enough LIQUID water present in the exhaust stream to cause thermal shock when it contacts the rear 02 sensor thimble

the rear 02 sensor heater will NEVER be turned on even if the cat should light off prior to the car 's reaching 50mph

thank me very much for clarification

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snowfish
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Basic GearHead

Thanks. :rocker Thought you'd moved to Lower Scvolia or something. :oshit

Welcome back. :cheers
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mwebb
Apr 12 2012, 11:46 AM
thank me very much . . .
I almost forgot this one . . .

It's good to have you back, mwebb!

https://www.google.com/#hl=en&output=search&sclient=psy-ab&q=site:geometroforum.com+mwebb+thank+me+very+much+&oq=site:geometroforum.com+mwebb+thank+me+very+much+&aq=f&aqi=&aql=&gs_l=hp.3...2123l12608l1l14211l30l28l0l0l0l0l1342l14119l2-5j7j7j4j3j2l28l0.llsin.&psj=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=c98d3a4d2852b109&biw=1024&bih=630
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iBLKBRY
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Geo Glenn
Apr 12 2012, 07:31 AM
dayle1960
Apr 12 2012, 06:56 AM
A CEL light on the cluster and when I plug in my scan gauge DTC P0420 is present
That is all of the information that o have. O have not taken it to a shop on put it on their computer.

You're going to have to put this test on the road or a chasis dynamometer, boss. An Ultra-Gauge will give you some sort of a reading of the O2 sensors, although not of mwebb graphic quality. Somewhere in the FSM, this is mentioned.
I use an Auto Xray scan tool. This unit is about 12 years old now, but it still has updates and is great for the early OBD2 cars. I love the operational data feature. I stick my wife in the drivers seat and tool around whilst fancying all of the info treats.
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mwebb
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FOG

consider this as well ....
Posted Image

this shows 2 Mode6 captures stacked on one screen , labelled as FREDs gas and Mobil gas , note the Long term fuel trim and the Mode 6 TID $01 test results
this cat is "new" aftermarket and a solid pass , but compare the difference that is caused by change in fuel alone
1.000 is the max allowed , FREDS gas Mode 6 test result for the cat .250
Mobil gas Test result .172
Fail is 1.000 for a max allowed , lower is better ,

this shows a 7.8% difference (delta) in the test results of the cat test Just by switching to better , not best quality fuel .

so what ? who cares ? what can you say ....

if your cat tests at 1.05 with FREDs gas , a fail , you may pass with a 1.05 - .078 = .972
max allowed is 1.00

sometimes a marginal cat can be made to pass
just buy using the correct fuel

note the long term fuel trim value , using different fuels , you can see a FE gain of about 1.6% ...
not huge
but at $4 per gallon that is about 6 cents a gallon savings

this shows the need to keep accurate record s to see which fuel your car prefers , in this case
the lesser quality fuel , shows better fuel economy .....

does it pay to use dogshnit oil ???
think about the garbage additives in the crap oil , that boil out of the oil and get picked up by the PCV
to be burned , then
deposited on your cat converter .... do you think that prolongs the life of your cat converter ?
shake your head no .
Edited by mwebb, Apr 13 2012, 11:19 PM.
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dayle1960
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Fastest Hampster EVER

Mwebb, that is the best answer I've heard you say as to why we should use the "good" alphabet labeled oil. Thank you, sir.

Your ability to talk the common man's language is getting better, too. Thanks for your input.
Edited by dayle1960, Apr 13 2012, 11:40 PM.
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dayle1960
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Fastest Hampster EVER

Now this really scares me.

I did just like that guy on the video said, take some lacquer thinner and pour it down the gas tank. (I bet mwebb is pooping his drawers on that). I had 1/2 tank of gas and poured 2 quarts of thinner in. The CEL didn't go off after running that tank of gas. So I filled it up at a Murphy gas station ($3.52/gal) and started running it. Got to work today with the CEL still on and when I left work to come home, my battery cable/terminal connection was making the metro die. I go and twist it and start the metro. Great, I say to myself, and notice the CEL is not lit. But that is expected because that is one way to clear a CEL.

Now comes the scary part......My CEL didn't come on driving home. I wonder if I actually "cleaned" my cat with lacquer thinner????

Anybody wanna chime in on this fix? If my CEL stays off, I will say this is a good way to get rid of that pesky P0420 code.
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mwebb
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FOG

you will not find this in a factory service manual


or choice C
the lacquer thinner killed 1 or more 02 sensors and now the CAT test will not run
at least some 02 sensor DTCs will need 2 trips to set the DTC

or choice D
the fuel system puked out some rubber seals
fuel trim is off the scale hi or low .... 2 trip code

do you have any "pending" DTCs ? 1 trip failed test and will set DTC and check money light on trip #2 ?

it's your car
if you feel the need to kill it .... it isn't illegal .... yet
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Deleted User

Hmmm . . .

Well, if it worked, good. :thumb

Otherwise, mwebb has indeed :shit . Right in your lap. :-/

It may be your check engine light burned out. :'(

Gotta watch out for what some of those YouTube guys say.
I mean, the guy could have said anything, and it would have come across as believable.
Cute accent.
I'm betting he gets all the girls. :wub:

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Bad Bent
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Facetious Educated Donkey

dayle1960
Apr 17 2012, 07:26 PM
Now this really scares me.
my battery cable/terminal connection was making the metro die. I go and twist it and start the metro. Great, I say to myself, and notice the CEL is not lit. But that is expected because that is one way to clear a CEL.
You know when you turn the key on the CEL light should come on for a second - see if the bulb blew out. Check for codes with a reader and see if there are any? You could jumper the diagnostic socket in the engine bay/glove box drive it and see if you get a CEL or disconnect an O2 sensor and see if you get a CEL. The easy sensor would be the IAT on the air cleaner that if disconnected sets the CEL.These are just ways to test the OBDII without a reader and they will go away in time after being reconnected.

If you are wondering about gasoline additives then mwebb runs "87 octane TOP Tier fuel with .25 oz acetone per gallon." Seafoam and Techron are naphthas. used in the engine for cleaning.

From http://www.lacquerthinner.net/paint-thinner-vs-lacquer-thinner/: "Naphtha is a petroleum based product which is a by-product of the distillation of crude oil. It is also used to thin rubber cement, adhesives, oil-based coatings and oil paints. It used to clean brushes and spray equipment."

"Mineral spirits are a mixture of saturated aliphatic and alicyclic hydrocarbons. It can be used in place of turpentine. It is less flammable and less toxic than turpentine. ...It is also used to clean screen printing screens that have been soiled with oil-based textile and plastisol inks"

"Lacquer thinner contains a combination of solvents able to dissolve various resins and plastics. Usually thinners have alkyl esters similar to butyl or amyl acetate, ketones such as acetone or methyl ethyl ketone, ethers like glycol cellosolves and alcohols and aromatic hydrocarbons like toluene. Simply put it is a clear or slightly colored liquid that dissolves the thick solutions of varnishes and paints, lacquer, oils, grease and other adhesive materials. It dissolves, dilutes and cleans basic lacquers."

Consider also that the major complaint of old gasoline is that it turns to a gum or "varnish" and well, if I read it somewhat correctly lacquer thinner would remove a "varnish."
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