My car failed smog test c emissions to hi

hard to say as to why it did not pass, but it sounds like you have a problem, most emissions are caused by too much hydrocarbins coming out the tail pipe, new cat converter,

Any codes? any problem tune up, catalytic convener, burning oil.

Most modern vehicles have 2 catalytic converters, there may be one located at the exhaust manifold, or be what's called a resonator. The resonator will look almost like a cherry bomb muffler, this is a crucial part of exhaust emissions.

Jose, I don't know if this will give you the answer you are looking for because there are many things to consider here. The exhaust gas recirculation valve (EGR) is one of the main things involved in reducing NO emissions. This valve is controled by the power control module. (PCM) This is your vehicles computer. The PCM monitors the vehicles speed and will command the EGR to open when the vehicle attains a certain speed, which is why the ASM test being done is recorded at two different speeds. At 25 MPH your vehicle failed the hydrocarbon (HC) emissions limit and this could be for a number of reasons. When is the last time you car was tuned up? Old spark plugs, wires, clogged air filters, oxygen sensors, leaking injectors (personal experience) or the PCV valve could be contributing to the results of the test. I guess that the easiest way to go is to tune up the engine replacing the spark plugs, wires, air filter and the PCV valve and don't forget to have the oil changed at the same time. Only then should have the vehicle retested and see what the results are. Should it fail again you may have to consider having the EGR or the catalytic converter replaced depending on what portion of the test fails. If the NO fails I would consider the EGR. If the HC fails then I would consider the catalytic converter. Good luck with this.

Not sure, but did you replace the oxygen sensors. Is your catalytic converter still good?

We had to have the calatic converter replaced. We did this after doing an oil change, air filter change, and new spark plugs and still hadn't passed smog. After changing the calatic converter it passed smog with scores of 25.

not enough info. Typically, CO and HC together can be the result of poor fuel control or misfire, or worn components such as O2 sensor or catalytic converter, but without more data, repair recommendations are likely to waste money and not achieve success.

You can try some over the counter solutions per say. Some of the mechanics in a bottle. They sell some products This will probably be the cheapest router. If this doesn't work then you need repairs.

Pass your emissions test.

you may need replace the catalytic converter, but 1st do this, clean the throttle body and idle airbypass valve, change the oil before the retest as well, get it as hot as you can before the test, hold it at a high idle prior to the test, this may squeak you by, as a 20 year smog tech these are the thing I did, if all else fails do the cat conv.

Do an oil change with 20W50 oil (or one grade higher) to prevent blow by during the test.

You current oil has HC from blow by though the rings.

Do a fresh oil change will lower the HC.

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Change spark plugs,wires,cap and rotor if they are over 24,000 miles
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Make the smog check appointment for the EARLY MORNING. Colder air will help the fuel burn better.

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Clean or change the air filter and pcv valve.

Clean Mass Air Flow sensor with CRC Mass Air flow cleaner or electronic part cleaner.

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Do a quick wipe down on the wires and cap to take the moisture off.

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Check spark plug wire contacts for corrosion.

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Fill the tank to around 3/4.......just in case your fuel pump is weak.

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Ran the truck for 20+ minutes on highway before the test.

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Do not carry excessive cargo on the truck bed.


These are the little things I would do to get the HC and CO down.


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