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I failed the emissions test because the car emits to much NOx. What repairs would you recommend?

Optional Information:
1991 Dodge Spirit 2.5L Non-Turbo

Already Tried:
No-Smoke treatment. Complete Fuel System Treatment

Customer (name blocked for privacy)

Status: Closed Value: $10

The timing could be too far advanced.The cooling system could be marginal and not cooling the engine well enough(fan not working or a clogged radiator).The egr valve is not functioning correctly.You have carbon build up in the combustion chambers.The o2 sensor is not switching fast enough or the convertor is about dead as far as doing it's job, not being clogged.

Master ASE Certified.L1 Advanced Engine Performance Certified.Pa Emission Repair Technician.Just Answer Car Category Mentor.

Reply to Davo/diablo666's Post: I think it may be the EGR Valve and I am going to replace that. I replaced the O2 sensor, I read that the converter on this car does very little in regards to NOx but is mainly getting rid of CO. The fan seems to be working and so does the radiator. How do I clean the build up in the combustion chambers, I tried Complete Fuel System Cleaner already?

Make sure the egr ports in the intake and exhaust are not restricted when you have the valve off.The best way to remove carbon from cylinders is to spray water from a squirt bottle into the throttle body.Don't over do it enough to make the engine stall just a mist will work.You could also tap into a small intake vacuum port and put a small hose from it into a bottle of water.if you choose the second method make sure you are at about 2500 rpm before yo place the hose into the water.Trust me this is no joke.Atf will do the same thing but makes a pile of smoke if you use it.The convertor does do a good bit to reduce nox as long as the O2 sensor is switching properly.That shouldn't be a problem because it is new.That's the reason O2 sensors are made the way they are.

Master ASE Certified.L1 Advanced Engine Performance Certified.Pa Emission Repair Technician.Just Answer Car Category Mentor.

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