Failed smog test
Thread Starter
Cruising
Joined: Jan 2008
Posts: 14
Likes: 0
Failed smog test
I"ve have a 1991 for the last 2 years that just failed its California smog test. During the test the car started to overheat which was odd. Never had that problem before. Found radiator core clogged. Thought maybe because of the heat, the car failed. I also want to replace plugs for best emmissions performance. Will any of these things help or is the cat. converter gone. Any advice will help.
Mark
Mark
Corvette Enthusiast
Joined: Oct 2007
Posts: 6,797
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From: So. Cal.
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I"ve have a 1991 for the last 2 years that just failed its California smog test. During the test the car started to overheat which was odd. Never had that problem before. Found radiator core clogged. Thought maybe because of the heat, the car failed. I also want to replace plugs for best emmissions performance. Will any of these things help or is the cat. converter gone. Any advice will help.
Mark
Mark
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
The first thing to do before any emissions test is to do a Complete tune up or at the very least change the spark plugs, oil, oil filter, air filter, and check the timing.
If you don't know the last time a tune up has been done, now is the time.
If you don't know the last time a tune up has been done, now is the time.
Thread Starter
Cruising
Joined: Jan 2008
Posts: 14
Likes: 0
Failed the emission test at both 15 mph and 25 mph.The results for 25 mph are below.
%C02 MEAS was 12.4
%02 MEAS was 3.1
HC (PPM) was MAX 61 AVE 19 MEAS 101
C0 (%) was MAX 0.42 AVE 0.06 MEAS 0.27
NO (PPM) was MAX 502 AVE 189 MEAS 1449
Hope this helps. Thanks
%C02 MEAS was 12.4
%02 MEAS was 3.1
HC (PPM) was MAX 61 AVE 19 MEAS 101
C0 (%) was MAX 0.42 AVE 0.06 MEAS 0.27
NO (PPM) was MAX 502 AVE 189 MEAS 1449
Hope this helps. Thanks
Last edited by pfsrst2; Oct 11, 2010 at 02:06 PM. Reason: Did not display right
Melting Slicks
Joined: Jan 2009
Posts: 3,482
Likes: 196
From: folsom california
high HC's, unburned hydrocarbons; try a complete ignition tune up first; rotor, rotor cap, spark plug wires, spark plugs.
high NOX, make sure egr valve works, all egr passages clear, and all vacumn hoses intact and hooked up.
only then would I look at the cats.
high NOX, make sure egr valve works, all egr passages clear, and all vacumn hoses intact and hooked up.
only then would I look at the cats.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
With that NOX #, the EGR isn't working and it should be spitting out a 32 or something similar and a Check Engine Light should be staring you in the face. Without EGR, it will heat up and then dump fuel.
I scan a car before I do anything as if fuel delivery is right and it doesn't pass, you can generally count on a new CAT. Given your high HC's that may be the case but you want to fix the EGR first.
I scan a car before I do anything as if fuel delivery is right and it doesn't pass, you can generally count on a new CAT. Given your high HC's that may be the case but you want to fix the EGR first.
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