? asked in Cars & TransportationCar MakesHonda · 7 years ago

94 accord failed texas emissions test high nox?

My 94 accord 4cylinder 130000 miles (no check engine lights or any lights are on) failed the emissions test because of high nox on high and low rpms high is 910 1478 low is 1006 1538....i cleaned out my egr ports wich were VERY VERY clogged up what else can i clean or do to make the nox drop? thanks

3 Answers

  • 7 years ago
    Favorite Answer

    Many ppl tend to neglect replacing the PCV valve bec many times it's located in a tough spot.I'd for sure replace it bec it's probably not been replaced in a long time.A few things I like to recommend doing before any emissions test is check//change the air filter, do a basic tune up on it such as the plugs and check the wires etc.You'd be surprised how even dirty oil can affect the emissions test results and I strongly recommend that if the oil hasn't been changed change it.Other things to do is maybe add some Lucas oil treatment instead of one litre of oil at the Lucas during the oil change.You may also want to flush the oil use something like STP and read the directions carefully.Don't have less then half or 3/4's of a tank of gas in the car when you go to have the emissions test done on it.

    Hope that helps and best of luck.By the way one thing I'd do for sure is pre-book the emission test and take the car for a long hwy drive then pull up to the shop just before the time it's booked for and leave the car running.Note once you change the oil and add the Lucas drive it a few days before you go to get the emissions test done on it.There a few tricks you can try look online for the the different additives etc you can try using.

  • 7 years ago

    new air filter. have a diagnostic check. possible sensor faulty.

    make sure rest of breathing system is ok such as PCV valve and hoses..EGR getting clogged is a result of excess oil.carbon in gases. possible engine worn? rings? valve stem seals?

  • Eric
    Lv 6
    7 years ago

    The PCV valve is likley gummed up also.

    Clean or replace.

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