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Forum > Failed Smog Test > Question

94' dodge dakota 3.9L v-6 keeps failing smog.

I have repeatedly failed smog, to the point now of being a gross polluter. everthing I have failed on, I repaired and passed that portion of the test. The only problem is my no2 are 5 times the average. Even after replacing the catalytic converter, my numbers have gotten worse. I would of thought that would of reduced them, but that was not the case. what does it sound like the problem can be? I am trying to research the hell out of this, without spending anymore money than I need to. Thank you,
Answer:

Your Dodge truck is probably suffering from a lean fuel mixture. I'll bet the CO levels are low. It may appear that the CO being low is a good thing, but technically it's not. See, the CAT needs a little fuel to work properly. A lean fuel mixture not only causes the engine to run hot (NOx is created when combustion chamber temperature go above 2500f; lean fuel does not help cool the engine down)) but it also doesn't let the catalytic converter start to work. Start with making sure the fuel feedback system is working properly. This includes making sure the oxygen sensor and all emissions sensors which tell the computer how much fuel to send the engine are working properly. nbsp; If I'm wrong and the problem is not air/fuel related, check the EGR system, obviously including the EGR valve. Your Dodge must have an exhaust restriction through the EGR system; whether is be carbon build up or defective EGR components, i.e.. EGR valve, EGR control solenoid, vacuum hoses ect. posted by SmogTips Support

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