I did a smog test and failed due to: just over the limit for hydrocarbon emission.

This is common in the Nissan's could be the cam and crank sensor these go at around 70000 to 120000 should do both at once to be safe. that will fail an emissions test for sure. hope this helps

it appears to need a major tune up, your fuel system is showing signs of alcohol poisoning, most of todays fuels are up to 10% alcohol, this engine and fuel system was not designed for it. You may hit the spending limit for emissions' before fixing it. Plugs, wires , cap , rotor, air and fuel filters is where it starts...keep me posted

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Emission test by codes reader? or smog? Any codes?

you need to do a major tuneup !!!!!!! replace air & fuel filters, spark plugs & plug wires, distributor cap & rotor, replace OXYGEN SENSOR, change oil & filter, hopefully your catalitic converter is ok, if not , it should be replaced !!!!!!!!!!! together w/tuneup would be the best way to assure passing emissions !!!!!!!!

I would replace CATalitic converter, this car is old, plus a tuneup is 100% necessary , spark plugs wires, ditributor cap & rotor, plus both the air & fuel filters need replaced. change oil & filter. then you will pass emissions test. and your car will run like its suppose too. if you don't do all this , then buy a new car !

Retarding the timing will cool the combustion which will lower the Hydrocarbon number,it will run bad but after a passed e test put the timing back to an advanced state which may help with the stumble.

Hi Larry, I your position I believe I would take the vehicle for a diagnostic scan and then check the read outs. There could be a problem with any one of a number of sensors but I believe you'll end up with all odds pointing at the cat. Regards John

I'm sorry, I'm not any good on this. Can anybody out there be of help?

Have you tried replacing the oxygen sensors. These signal to lean the gas or rich the gas for emissions.

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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