QuestionMy toyota camry 91, 4 cylinders failed inspection 4 times; emissions is the problem, I changed the oxigen sensor, wires, distributor cap,spark plugs,air filter,and gasoline filter and the problem persist.
These are the results:
NOx 970-----reading 1165
HC 128 '' '' 165
Could be the EGR Valve?
Thanks for your help
AnswerA mafunctioning egr system will turn the check engine light on, is there a check engine light?
If so, what is the trouble code?
High NOx readings are caused by engine timing out of adjustment or a malfunctioning egr system which is supposed to reduce this gas,another reason is high combustion chamber temperatures, this could be caused by carbon build up in the combustion chambers or engine overheating.
The high hydrocarbon reading is an indication of incomplete combustion( not all of the fuel is oxydized in the combustion process)this could be an engine misfire for some reason, finally a three way catalyst could also be causing the high readings because of a degradation internally.
