1993 Corolla Just Failed Nj Emissions. Help, Need To Pass Or I May Ha



Hello All,

I have a 1993 Toyota corolla DX automatic trans and a 1.8 engine. We are just about to 210,000 miles. I failed NJ emissions. A year or two ago i failed inspection and replaced the cap, rotor, wires, and put in platinum plugs. Which didn't help, then i replaced the catalytic converter and she passed. There was a pin hole leak through the center of the material inside the cat when i replaced it, but that cat had 150-170,000 miles on it. She burns or pushes some oil. About a quart every 1000 miles. I do all highway high RPM driving so i expect some oil pushes out the valve cover gasket and some gets burned. Check out the 1st emissions test...


HC ppm 570/220 fail

CO% .62/1.20 pass

CO2% 13.5

O2% 1.3

High idle

HC ppm 587/220 fail

CO% .68/1.20 pass

other readings about the same.

I was going to replace the O2 sensor just fun. But the parts store gave me the wrong one. So after reading some posts about passing emissions. I had a half tank of gas about 5 gallons which i added one bottle of dry gas with iso-alcohol. did a test drive to get some into the engine. Next day i added another bottle of dry gas and went to inspection. Here are the results...


HC ppm 506/220 fail *****no real change******

CO2% .77/1.20 pass

High idle

HC ppm 256/220 fail ****** so close*****

CO% .56/1.20 pass

I'm going to pull a spark plug to check it and check the air filter. Someone posted that the air filter change made their car pass. I've been looking at new cars all week and i just keep coming back to my corolla. Nothing really makes me say that's the car i want. Versus a 1993 model that gets great gas mileage and starts every time with no let downs. Not really feeling like putting a new engine into this car. All help is appreciated.




bent rod

New member
Its a high milage car so that doesnt help( lower compression ).

Your burning a fare amount of oil. I have been told by my smog guy that burning oil will not really affect your smog #'s,but it can shorten the life of the cat and foul your o2 sensor.

Your HC #s are pretty high.

Hows the compression? I would check that first. If thats bad, nothing you do will help.

Is the car missing ? That will give you a high HC.

If your compression looks ok. I would do a tune up( plugs, wires , cap, rotor, adjust valves , timing, clean throttle body, check MAP, EGR).

Make sure that the car is running at normal operating temprature( your temp gauge should be about in the middle once the car is warmed up, and you should have good heat in the car.)If its not, I would check your thermostat.( can make the car run richer).

If thats ok I would check your coolent temprature sensor, if this is bad in can really make your engine run rich.

If all that looks good I would check your fuel pressure and if its to high, check your fuel pressure regulator.

Your cat could be bad also, but even if your cat is bad your HC is still to high.

And when you go in for your smog test make sure the cat is up to operating temp. go drive on the freeway for about 1/2 hour right before your test.

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