my 93 civic failed emission. need help.

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07-01-2009, 07:04 AM

yuprety

Junior Member

Thread Starter

Join Date: Jul 2009

Posts: 1

my 93 civic failed emission. need help.

i failed texas emission test due to super-high nox reading. does anyone have suggestion. here are the reading.

25 mph 15 mph
HC: 167/54 pass 173/80 pass
CO: 0.94/0.02 PASS 0.97/0.02 pass
Nox: 1240/2899 fail 1372/3036 fail

please help asap.

07-01-2009, 04:14 PM

hamorhead

HCF Member

Join Date: Jun 2008

Location: Florida

Posts: 1,190

What mods are done to the car?
And if it has the stock engine what is it?(if you don't know just post the trim level of your car)

07-01-2009, 04:55 PM

RonJ

Recognized HCF Member

Join Date: Sep 2007

Location: Houston, Texas

Posts: 9,453

Is the CEL ON?

High NOx levels indicate that the engine is running hot or lean or that the cat is bad. As your engine appears to be running lean, check the O2 sensor, the fuel pressure regulator, and the fuel pressure.

07-01-2009, 08:23 PM

conceptualpolymer

HCF Member

Join Date: Sep 2005

Location:

Posts: 906

Among the potential causes of non-compliant NOx readings are:

Misfire condition
Malfunctioning or improperly adjusted EGR valve
Failed oxygen sensor
Leak in exhaust tubing upstream of converter
Excessive carbon deposits in combustion chamber
Improper spark advance
Blocked coolant passage
Overly lean air-fuel mixture
Damaged cold air duct
Failed or malfunctioning catalytic converter
Corroded or damaged engine sensor electrical connections