<VV> No Corvair - GM Catalyst Replacement?

[Sethracer at aol.com]

In a message dated 1/13/2009 3:48:17 P.M. Pacific Standard Time,  
gyoungwolf at earthlink.net writes:

If  anyone has done a converter replacement on a late model GM vehicle (this 
one  is a Tahoe), please drop me a note. I am wondering about the impact on 
the  computer functions if the coverter is replaced with a straight pipe. (Don't 
 need advise that it is illegal as it does not belong to me and the owner is  
aware of that :-).
Thanks,
Grant



The late model GM Computers have connections to a pair of Oxygen sensors,  
one before and one after the converter. On initial start-up, the computer will  
check to see if the oxygen sensor is there and providing computer input that  
says it is within the correct operating range. (Raise your hand if you are  
here). After operation begins and the catalyst begins to operate, the computer  
tests to see if the "after" O2 sensor is showing an improvement from the O2  
sensor located before the converter. If it doesn't, This will set a "Check  
Engine" light and set the appropriate code in the computer. At that point, the  
car will not pass a smog test.
 
Not a "legality" statement, but I don't want to breathe his smog. - He  
should get it fixed. The running of the car may not be too affected, because the  
before O2 sensor is providing feedback to the fuel system controls. The system, 
 however can make the car run rich at some point, because it is counting on 
the  converter to clean up it's exhaust. Removing the converter may, indeed 
cause the  truck to pollute a lot more than an older car. Seems strange, but that 
is what  allows new cars to run so well.
 


Seth Emerson

C's the Day! -  Corvair, Camaro, Corvette




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