Question about 1991 Honda Accord

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92 honda accord high nox at smog check

It passes at 25 mph but fails at 15 mph

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  • David Melrose May 11, 2010

    (Emissionwiz have you seen this one?) Usually high nox is a sign of an engine that is running too lean. Vacuum leaks can introduce air that is not measured by engine sensors and lead to lean mixtures. A malfunctioning EGR valve can also lead to high nox levels. So check those areas first.

    I have had very good luck with a CRC product called "Guaranteed to Pass". You treat one full tank of gas and use the tank down to empty, then refill with gas and take the smog test. The only problem is that it is not a quick fix. It takes time and mileage to clean your engine. But it has never failed to significantly drop my emission numbers. I use it every year and it drops my (15mph) Nox numbers from about 1000 down to 600--once down to 83! Note: Guaranteed to Pass only works with a properly functioning emission control system. It may help cover malfunctions but doesn't claim that it will.

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Posted on Jan 02, 2017

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jasperoni
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SOURCE: my c220 failed smog because of high hydrocarbons at 25 mph

hc's are unburned fuel- I would change my sparkplugs and resmog it if that is the only gas that was high

Posted on Jun 01, 2009

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SOURCE: 02 kia fail smog high nox

if the engine computer says that you have a slow O2 sensor what it means is that the sensor does not react as quickly as it should and it needs to be replaced. nox is oxides of nitrogen, a product of too lean combustion which causes cylinder temps to go too high. it sounds like replacing O2 sensor will make it happy. engine computer is having a hard time controlling lean/ rich fuel mix because sensor is slow to register changes, needs to have response time in milliseconds or engine computer can't operate properly. O2 sensors do wear out, normal service item. hope that helps

Posted on Jun 17, 2009

  • 12 Answers

SOURCE: 1987 honda accord lx failed smog 2nd time. even

true the EGR can really make a change and it should have been the first thing too look at because its the cheapest and easy to install

Posted on Feb 19, 2010

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1 Answer

How is ignition timing regulated? Car gets 99 BTDC on ignition timing and failed SMOG Test in CA. Listed as GROSS POLLUTER.


something wrong here
with 99 degrees btdc it will not run
have you got it on the correct plug lead
next the timing is regulated by centrifugal advance if electronic or points and by the crankshaft position sensor if ECM controlled ( some after market distributors that are used in place of points units have a small sensor in the distributor that can adjust the timing according to engine rpms, but it cannot make allowances for mixture and so they can advance the timing but not take into account anything else which sometimes results in detonation under certain throttle settings
so initial setting for most cars is 10-12 degrees btdc at idle and with engine rpms set up to 3000 rms it may advance to 25-30 degrees depending on the advance mechanisms
with ECM units the timing is controlled by the crank position sensor and is set to parameters according to engine rpms and air/fuel ratio settings but it still has a basic 10-12 degrees btdc on starting
to fail smog tests you probably do not have a working cat converter and other problems besides timing

Sep 15, 2016 | Cars & Trucks

1 Answer

NO ppm CA. smog at 15mph too high


NOX is high coolant or engine temps
& egr issues

Lots on the internet to study on exhaust gases
& the reason they fail inspection or are too hi

Mar 26, 2014 | 1995 Dodge Dakota

1 Answer

Failed MEAS


wow, no context but i can read your mind?
ok SMOG failed. right?
what speed, there are 2 in uSA, 15 and 25.mph.
so there are 3 tests, which one. all are PPM in usa.
parts per million.
but is that HC , CO, or NOX? or ?

based on your numbers is HC
hydrocarbons or in barstool, its raw gasoline leaving rear of car.
unburned fuel..

572 ppm is way too high 12-19 is normal
id say the CAT is bad.
but can be , engine is bad, and burned out the cat.
that is why all savvy mechanics, check the that the engines
holds closed loop status, (EFI closed loop) at the speed yours failed.
if not in closed loop the cat will burn up (rich)
that is first.
Once that is cured. you check HC again. if out of spec
you did burn up the can , new cat time.

that is the correct way.

Feb 19, 2014 | 1998 Toyota Tacoma

1 Answer

High nox fail smog test any remedies? 99


NOX is created when the internal combustion temperature gets to high.The egr system uses burnt exhaust gases to line to cylinder walls.The purpose of this is decrease internal combustion temperature therefore reducing the amount of NOX created.Would look to a possible egr malfunction usually they will trigger the check engine light but not always.The 4.3L has been known to have issues with carbon buil up in the egr and the egr pintle not open and closing properly.

Jun 07, 2010 | 1999 Chevrolet Astro

1 Answer

1987 honda accord lx failed smog 2nd time. even after installing a new catalytic converter. passes at 25 mph, fails at 15 mph, what can i do now? told somethng to do with egr valve maybe.


true the EGR can really make a change and it should have been the first thing too look at because its the cheapest and easy to install

Feb 19, 2010 | 1987 Honda Accord

1 Answer

02 kia fail smog high nox


if the engine computer says that you have a slow O2 sensor what it means is that the sensor does not react as quickly as it should and it needs to be replaced. nox is oxides of nitrogen, a product of too lean combustion which causes cylinder temps to go too high. it sounds like replacing O2 sensor will make it happy. engine computer is having a hard time controlling lean/ rich fuel mix because sensor is slow to register changes, needs to have response time in milliseconds or engine computer can't operate properly. O2 sensors do wear out, normal service item. hope that helps

Jun 17, 2009 | 2002 Kia Optima

1 Answer

My c220 failed smog because of high hydrocarbons at 25 mph


hc's are unburned fuel- I would change my sparkplugs and resmog it if that is the only gas that was high

May 20, 2009 | 1994 Mercedes-Benz C-Class

1 Answer

Failed smog


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.

Mar 17, 2009 | 1992 Mazda Protege

1 Answer

Failed Smog Test Close to CA-HC Limits


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.

Jan 03, 2009 | 1992 Honda Accord

1 Answer

2001 Sonata V6, Smog failed - high NOX


if i were you i would contact cragen and ask them if the car has it and how much the replacement part is

Aug 19, 2008 | 2001 Hyundai Sonata

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