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Old 01-12-2006, 03:10 PM
Duke2.6 Duke2.6 is offline
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Join Date: Mar 2003
Location: Southern California
Posts: 2,272
Originally Posted by cam69ss
That car failed for NOx not CO.
You need to follow the same general troubleshooting proceedure as outlined in the referenced threads, and retarding the ignition map will both lower NOx and HC/CO.

Look at the effect that retarding the igntion map had on all emissions relative to my previous test.

As always, troubleshooting starts with checking the duty cycle and O2 sensor output waveform.

Since there is no easy way to test catalyst efficiency, you test and check EVERTHING else and then retard the timing map if necessary. If this fails change the catalyst as a last resort (since its very expensive) I think a lot of good catalysts are thrown away on a whim without thorough troubleshooting or retarding the timing map. Most shops don't understand the generation and control of emissions and just change parts until it passes, which can end up costing nearly as much as these cars are worth.

Your choice - find a shop (if possible) that knows how to troubleshoot and correct emissions problems, or learn yourself by reading various emission test threads, and downloading all the service information and STUDYING it thoroughly so you understand the how the various emssion control systems/components work.


Last edited by Duke2.6; 01-12-2006 at 03:16 PM.
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