Question about 1995 Geo Prizm

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Had car emission tested and car failed test on the following, nox (ppm): standard is 1072 current reading 1752 results failed 1186 rpm 2301 at 25 mph and 3619 at 15 mph rpm 1812, what could be the cause of this and what needs to be replaced

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Hi! This surely is a faulty ECM (engine control module) issue. THe ECM controls the air and fuel mixture of the engine. If the ECM fails, surely will fail on emission tests. Have the PCM replaced and you'll be good. HOpe this helps and thank you for using FixYa!

Posted on Sep 08, 2010

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Generally, NOx should be taken care of with the EGR Valve which mixes exhaust gases with the intake air so that the temperatures of the combustion chamber does not go above a certain point.

So, I would say the EGR Valve is a part of this problem.

According to About.com::

The EGR valve helps your car more efficiently and completely burn fuel by recirculating a portion of your exhaust and running it through the combustion process again. This results in a cooler, more complete burn of the fuel which decreases you car's noxious emissions by prohibiting the formation of some harmful gases.

Posted on Sep 03, 2010

  • Duane Wong
    Duane Wong Sep 03, 2010

    Also, a defective Catalytic Converter, if so equipped, can cause the NOx to be too high, because the high heat and catalyst of the Catalytic Converter converts NOx to simpler non harmful products.



    According to Wikipedia:



    Three-way

    Since 1981, three-way catalytic converters have been used in vehicle emission control systems in North America and many other countries on roadgoing vehicles. A three-way catalytic converter has three simultaneous tasks:


    1. Reduction of nitrogen oxides to nitrogen and oxygen: 2NOx → xO2 + N2

    2. Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2

    3. Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water: CxH2x+2 + [(3x+1)/2]O2 → xCO2 + (x+1)H2O

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Failing emissions testing due to high NOX (oxides of nitrogen)


I have seen several people posting emissions failures due to high NOX (oxides of nitrogen). Nox is created when the engine's internal combustion temperature gets to high.

Two reasons this can occur is improper coolant levels and a malfunctioning egr system. The egr system injects exhaust gas from the exhaust and uses it to line the cylinder walls.This in turn reduces the combustion chamber size and internal combustion temperatures. Ultimately this reduces the amount of NOX created. These systems functioning properly can be the difference in passing or failing your emissions testing because of high NOX ppm.

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My 1989 Mercedes 260E has no EGR valve and CA emission test failed NOX. What's next?


You engine came with EGR, here is a picture of it, make sure it is functional.808daddd-23be-456e-979e-50a2188da73b.jpg

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Fail smog test


fist i would like you to post the year make and model of the truck along with the HC ppms and NOX ppm it would be very helpful but high hc and nox can be attributed to a faulty EGR system nox is produced when the combustion chamber temperature gets too high so a small amount of exhaust is cycled back into the air stream to help cool them there are other causes but without looking at the levels its much harder to say

Dec 06, 2012 | Cars & Trucks

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1985 Plymouth Voyager 2.6 L failed NOX emission test


1) please RUN the scanner and computer test from any repair shop you must get the exactly faulty in your emission system
2) However you can go to the www.automecanico.com+ www.autoelectronico.com this sites is in spanish, but you can translate with your web browser and I Higly recomend because has Powerful information update for any cars models, Try it and fix it.
God bless you

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My 1997 Honda Civic failed it's Emissions Test. See below the ASM Emission Test Results. What do you suggest I do to get the car to pass the smog test? ASM Emission Test Results: 15mph - RPM = 1587...


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.

Apr 05, 2011 | 1997 Honda Civic

1 Answer

1991 Honda Accord LX failed EVAP test. The ASM Emission Test Results showed Test 25mph RPM 1933, %C02 MEAS 14.60, %02 MEAS 0.22, HC (PPM) MAX 61, GP 236, MEAS 19, CO (%) MAX 0.60, GP 2.10, MEAS 0.02, NO...


Things to consider or replace...

If you are getting a Check engine Light let me know, it will make things easier to diagnose.

Catalytic Converter
Oxygen Sensor
EGR Valve

May 17, 2010 | 1991 Honda Accord

2 Answers

My 91 Accord has failed a total of four times in two days. The converter has been changed twice in as many days. The car failed the NOx ortion of the test. The results are as follows: Test 1: Low speed...


It sounds like you need a tune up and to clean the injectors take care of all the performance issues before you even begin the smog my suggestion would be plugs and wires and 100% that it can be your O2 sensor that is why your not passing that cost about $40 to $160 at a parts store and $40 to $90 to install good luck

Sep 24, 2009 | 1992 Honda Accord

3 Answers

ASM 2525 NO ppm TAILPIPE EMISSIONS failure


have you had the the engine codes pulled and reset?
and if so what are your engine codes?
i dont know of any car that will pass emissions test with the engine light on.
we cure your trouble that caused your engine light to come on and you will pass your test.
later
paul

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