| Here is a good link.. [ http://www.916smog.com/smog-help.html ] Higher combustion Temps results in more NO.. early Ignition Timing causes the Combustion to take place faster and hoter.. and the engine runs better ( usually ).. that is why in the 70's when NO emissions came in, the cars got REAL Doggy.. took the engine designers a while to figure out how to make power, and keep NO down also.. Check Ignition timing.. if it is OK, then start looking at the EGR Valve and it's vacuum hoses.. the EGR 'Poisons' the Combustion process so it burns slower, and cooler.. less NO.. The EGR is only used during partial throttle conditions.. WOT it's turned off Then check Cam Timing.. USUALLY cam timing will also affect HC's.. but that is not true..
Cj
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