Failed CA emission - high NO

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Originally Posted By: mehullica
You have a higher than normal level of O2 on your readings. A vacuum leak or lean mixture will raise the O2 levels. Your HC & CO are decent which means you're not having a catalytic converter issue. I think your engine has a small vacuum leak causing a run too hot & fail for NOx. Can you check your O2 readings with a scantool or the obd port with a voltmeter?


Yes, I have an OBD II scanner. What data should I look at?
 
Originally Posted By: mehullica
You have a higher than normal level of O2 on your readings. A vacuum leak or lean mixture will raise the O2 levels. Your HC & CO are decent which means you're not having a catalytic converter issue. I think your engine has a small vacuum leak causing a run too hot & fail for NOx. Can you check your O2 readings with a scantool or the obd port with a voltmeter?


I think '96 Camaros have an air pump (electric) that introduces additional air into the catalytic converter. If an air pump is present, there will always be excess O2 present.
 
Look at your o2 voltages at 2500 rpm on a hot engine. Look at the voltage changes to see if they are switching above & below .5 volts at least a few times a minute. Then let it idle & watch the voltages. Should be above .6-.75 volts at idle with little or no switching under .5 volts.
 
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