Quote:
Originally Posted by mxexux
^^^ ya but how would a clogged EGR cause high HC's and CO? The numbers seem to say that it is running rich to the point of misfiring at idle.
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The amount of HC and CO exiting out the exhaust is basically regulated by the EGR either before or within the catalytic converter to be routed back into the engine to be burned. Whatever is left over is supposed to be trapped in the cat. If either of those fail, then the result will be too much emissions exiting the exhaust. So, it could be a couple of reasons:
1) clogged EGR valve or recirculatiion tube
2)catalytic converter failure
3)EGR valve not recieving signal or vacuum(depending on what type of EGR)
4)faulty EGR valve
Any of those could be the reason. Since you said that he also failed a visual inspect, it may be that his EGR may have been unplugged for whatever reason.
EDIT: Nevermind on that last statement. Just looked at the sheet, it says that EGR passed functional test