Project "Blown HD" my 6/8 drop/shortblock/heads/cam/blower/tranny install
03-19-2006, 12:11 AM
#221
TECH Veteran
Originally Posted by BlownChevy
Hey Kevin, I have been meaning to ask you....How is that Trailblazer SS you dont have?
And it's just fine, thanks.
03-19-2006, 02:41 PM
#222
I have been getting some random P0420 codes lately that I have cleared and wanted to share what the explination for them was. This is from oxidizr, and is a common occurance when switching to LT's & high flow cats. I figured it might help some of you guys out in the future during your switch. It certainly cleared things up for me:
"Cat low efficiency (420/430) simple means the change between measured o2 before and after cat is too close ... High flow cats often suffer from this coupled behind LT headers.
This code only appears after prolonged low throttle freeway speed cruising .. should not appear during usual daily driving traffic. This is a function of reduced residence time or for a lack of better terms too short a burn period in the cat. As a cat flows better, the gasses pass through faster, burning off less of the residual fuel before the sensor can read it. The lower "measured" conversion rate may cause the code but more times than not has no bearing on the tail pipe emissions."
did I ever mention how smart this guy is?
damn impressive
"Cat low efficiency (420/430) simple means the change between measured o2 before and after cat is too close ... High flow cats often suffer from this coupled behind LT headers.
This code only appears after prolonged low throttle freeway speed cruising .. should not appear during usual daily driving traffic. This is a function of reduced residence time or for a lack of better terms too short a burn period in the cat. As a cat flows better, the gasses pass through faster, burning off less of the residual fuel before the sensor can read it. The lower "measured" conversion rate may cause the code but more times than not has no bearing on the tail pipe emissions."
did I ever mention how smart this guy is?
damn impressive
Last edited by moregrip; 04-25-2006 at 11:13 PM.
03-19-2006, 03:12 PM
#223
TECH Veteran
If the goal of a catalytic converter is to convert, I don't see how little to no conversion ("the change between measured o2 before and after cat is too close..." as quoted from above) could be good. Sounds like the new cats aren't doing their job (at least at highway speeds), and the thrown code is an indicator of this.
03-19-2006, 03:32 PM
#224
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Originally Posted by TBSS
If the goal of a catalytic converter is to convert, I don't see how little to no conversion ("the change between measured o2 before and after cat is too close..." as quoted from above) could be good. Sounds like the new cats aren't doing their job (at least at highway speeds), and the thrown code is an indicator of this.
A job of a catalytic convertor is to convert. True, but not convert O2 ... HC and NOx are the culprit gases ... unfortunately we don't have HC and NOx sensors on cars and the O2 content is used for reference. Your O2 sensors are total incapable of knowing how much conversion really happens and they can at best, only estimate based upon some crude O2 crosscounts. Put it this way ... a devise simply containing a high syria content wash coat on a ceramic substrate that had no effect on emissions conversions (0 precious metals) can keep lights from triggering.
The reason Car Sound/ Magnaflow cats do not contian such a high syria content washcoat is because we are not in the buisness of "fooling" sensors ... our cats are formulated for conversion (As a matter of fact the cats in question here are already EPA approved peding CARB with the loading as noted.) Understand that the addition of LT headers NOTORIOSLY effects residence time and O2 inefficiency codes ... few converters can maintain "normal" operation under these conditions.
Rest assureed the cats are fucntioning as designed and up to par.
03-19-2006, 09:06 PM
#226
Originally Posted by oxidizr
A job of a catalytic convertor is to convert. True, but not convert O2 ... HC and NOx are the culprit gases ... unfortunately we don't have HC and NOx sensors on cars and the O2 content is used for reference. Your O2 sensors are total incapable of knowing how much conversion really happens and they can at best, only estimate based upon some crude O2 crosscounts. Put it this way ... a devise simply containing a high syria content wash coat on a ceramic substrate that had no effect on emissions conversions (0 precious metals) can keep lights from triggering.
The reason Car Sound/ Magnaflow cats do not contian such a high syria content washcoat is because we are not in the buisness of "fooling" sensors ... our cats are formulated for conversion (As a matter of fact the cats in question here are already EPA approved peding CARB with the loading as noted.) Understand that the addition of LT headers NOTORIOSLY effects residence time and O2 inefficiency codes ... few converters can maintain "normal" operation under these conditions.
Rest assureed the cats are fucntioning as designed and up to par.
The reason Car Sound/ Magnaflow cats do not contian such a high syria content washcoat is because we are not in the buisness of "fooling" sensors ... our cats are formulated for conversion (As a matter of fact the cats in question here are already EPA approved peding CARB with the loading as noted.) Understand that the addition of LT headers NOTORIOSLY effects residence time and O2 inefficiency codes ... few converters can maintain "normal" operation under these conditions.
Rest assureed the cats are fucntioning as designed and up to par.
Good info Richard! Thanks
03-19-2006, 10:25 PM
#227
TECH Veteran
Originally Posted by oxidizr
It's a good thing I don't rely upon what you think and actually know what I'm talking about. You have honestly got to be the most negative and ill willed person I have ever come to know ... do you do anything other than critique thigns you don't fully understand and thread follow people you don't like? geez. I hope i read this right, but man .. I just don't get your tone sometimes.
A job of a catalytic convertor is to convert. True, but not convert O2 ... HC and NOx are the culprit gases ... unfortunately we don't have HC and NOx sensors on cars and the O2 content is used for reference. Your O2 sensors are total incapable of knowing how much conversion really happens and they can at best, only estimate based upon some crude O2 crosscounts. Put it this way ... a devise simply containing a high syria content wash coat on a ceramic substrate that had no effect on emissions conversions (0 precious metals) can keep lights from triggering.
The reason Car Sound/ Magnaflow cats do not contian such a high syria content washcoat is because we are not in the buisness of "fooling" sensors ... our cats are formulated for conversion (As a matter of fact the cats in question here are already EPA approved peding CARB with the loading as noted.) Understand that the addition of LT headers NOTORIOSLY effects residence time and O2 inefficiency codes ... few converters can maintain "normal" operation under these conditions.
Rest assureed the cats are fucntioning as designed and up to par.
A job of a catalytic convertor is to convert. True, but not convert O2 ... HC and NOx are the culprit gases ... unfortunately we don't have HC and NOx sensors on cars and the O2 content is used for reference. Your O2 sensors are total incapable of knowing how much conversion really happens and they can at best, only estimate based upon some crude O2 crosscounts. Put it this way ... a devise simply containing a high syria content wash coat on a ceramic substrate that had no effect on emissions conversions (0 precious metals) can keep lights from triggering.
The reason Car Sound/ Magnaflow cats do not contian such a high syria content washcoat is because we are not in the buisness of "fooling" sensors ... our cats are formulated for conversion (As a matter of fact the cats in question here are already EPA approved peding CARB with the loading as noted.) Understand that the addition of LT headers NOTORIOSLY effects residence time and O2 inefficiency codes ... few converters can maintain "normal" operation under these conditions.
Rest assureed the cats are fucntioning as designed and up to par.
03-19-2006, 11:16 PM
#229
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