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CODE 420; BAD CAT
Topic Started: Apr 16 2011, 05:16 PM (1,403 Views)
bigsquat
Member
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so i have a cade 420 and was wandering if it would be the front or back cat? the price is high for california legal cats. i think there made from unicorn horns. $203 for the rear, aND $257 for the front! i could drive to nevada and get a universal rear one for $80. or less. the front is so short that it looks like only a direct fit only would work. and if i go out of state i could have problems with the inspections here. i always wondered what the smog techs were looking at when they look under thge car. (to see if the cats are c.a.r.b approved i guess)

i really screwed up on the purchase of this car. i didnt let all the signals i was getting from the po sway me from the deal. he wanted to meet me to sell me the car at a place other than his residence, he was under the hood fumbling with something while i drove up, ( probably discoed the battery to kill codes)and he had a hard time speaking english on some of my questions but not all. i paid top dollar for a lemmon. the dam thing ran good on the test drive but when he left it wouldnt start for quite a while. its a good thing i had my car trailer.
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Good bye


PO420 is low cat efficiency. California cars have two cats, where in the exhaust stream are the O2 sensors? The front sensor controls a/f ratio and the rear monitors cat efficiency. So if they read the same this means either the cat is empty or dead usually with burnt oil. I think you can look into the front cat by dropping the pipe down from the manifold ( and probably the sway bar ). The rear cat is another story, I would proceed based on what the front one looks like. If the cat is melted you will have to address the oil issue before destroying your new cats. The car is worth fixing by fuel savings alone + you get to talk to everyone on this forum!!!! :)
Edited by Good bye, Apr 16 2011, 05:45 PM.
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bigsquat
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thanks, i was thinking about dropping the exhaust as you suggested. im hopping its the back one! i just talked to a guy who said the front one is called a precat ,but i dont know what that means. its only about 4-3/4" flange to flange. i see a o2 sensor at the exhaust manifold and one after the 2nd cat. thats all there are 2 right?

i have had the pleasure of talking to guys on this forum for a few weeks now and its been helpfull. see:(WONT START) this is just one of many problems that have come up in a short time. the po must be thanking his lucky stars when he sold me his nightmare!
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bigsquat
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i did some reading on the precat and found an interesting thread: http://www.toyotaownersclub.com/forums/index.php?showtopic=70844
it seems that the precat isnt as important as i thought. or is it.....
Edited by bigsquat, Apr 16 2011, 06:32 PM.
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Good bye


I would look at the pre-cat and if it is ok just replace the rear cat. If they smog check your car warmed up it might pass with just a new rear one.
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CityConnection
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Sir, yes sir!

I thought your county only had smog checks for change of ownership.
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CityConnection
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Sir, yes sir!

Never mind. I used your zip and saw that you're in a partial enhanced check area.
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mwebb
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FOG

IF the rear 02 sensor is behind cat #2 then you will need both cats , and do not even bother with aftermarket cats .
you may be able to install a CORRECT
front 02 sensor that operates as fast as or faster than an OEM specification sensor

do not even bother with white box chinese junk , the cats must hold the feed gases until the 02 sensor switches , so if the 02 sensor is slow and switches slowly then the cats have to hold the gases longer .... if that extra time exceeds the cat's ability , the system will code -
BUT
if the 02 sensor switches in less time than the cat has the ability to store the gases , then the system will not code
you can see how close your cat is by looking in

(using an enhanced OBD2 scan tool or a Generic with MODE 6 capability , not a wheel chock dogshnit code reader like scangauge)
MODE 6
the cat converter test is
TID 01 if that test fails close to the min or max limit then you may be able to squeak by with an OEM Front 02 sensor

(a new OEM cat will pass the TID 01 test using only 10 to 25% of the range to the min or max limit , OEM VW cats are under 10% of that range ... the farther from the min or max limit , the better
a marginal cat may exceed the fail limit by 5 or 10% and still squeak by with a new front 02 sensor , a fail of more than 25% over or under the min or max limit can not be resolved with a new 02 sensor )

in the same manner , it is in your interest to have the rear 02 sensor switching very slowly , do not replace the rear 02 sensor at this time
Edited by mwebb, Apr 16 2011, 08:03 PM.
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bigsquat
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i will drop the exhaust and do a visual. i just bought it and havnt smogged it yet . after that its every 2 years. with 4 vehicles im always smogging something! at least i dont have the motor home anymore(it cost more to smog)
mr webb your terminology is above my pay grade, so where do i buy the front o2 sensors you speak off.?
is it always necessary to change the front o2 sensor when you do the cat?
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mwebb
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FOG

bigsquat
Apr 16 2011, 10:39 PM
i will drop the exhaust and do a visual. i just bought it and havnt smogged it yet . after that its every 2 years. with 4 vehicles im always smogging something! at least i dont have the motor home anymore(it cost more to smog)
mr webb your terminology is above my pay grade, so where do i buy the front o2 sensors you speak off.?
is it always necessary to change the front o2 sensor when you do the cat?
your pay grade is not relevant
if you have a half a brain you can learn what Mode 6 is as it relates to cat converter condition
select your car and engine form this list
http://service.gm.com/gmspo/mode6/metro_tracker.html

study and learn

then locate a friend or a local independent repair shop that says yes when you ask them if they have a scan tool that can translate Mode 6 in your car / system

OBD 2 is here but OBD 3 is coming
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bigsquat
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(OBD 2 is here but OBD 3 is coming ) great, i didnt mind my wife leaving or pokerstars closing down and keeping my money but this is to much!
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Johnny Mullet
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Fear the Mullet

Visually inspect the cats and replace as needed. Perform a compression test for the hell of it.
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mwebb
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FOG

Johnny Mullet
Apr 16 2011, 11:54 PM
Visually inspect the cats and replace as needed. Perform a compression test for the hell of it.
assuming that the catalytic converter is not rusted through or physically damaged
what on the catalytic converter would you suggest to visually inspect
to
determine the actual condition of the cat ?
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Johnny Mullet
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Fear the Mullet

Easy. Drop the 4 bolts off the manifold for the precat. Melted? Continue to drop rear pipe and look for signs of platinum (shiny metal). See it all the time. 90% of all Metros that have low compression have a melted cat.
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mwebb
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FOG

Johnny Mullet
Apr 17 2011, 12:05 AM
Easy. Drop the 4 bolts off the manifold for the precat. Melted? Continue to drop rear pipe and look for signs of platinum (shiny metal). See it all the time. 90% of all Metros that have low compression have a melted cat.

most bad Cats that i see are not melted and in fact look the same as any other cat
inside
and
outside

so
imho
the correct is answer is choice C

i can NOT determine the condition of a cat converter by visual inspection and i would be very surprised to find someone who could
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