Car: 1995 Saturn SL1 SOHC, 1.9L.
Symptom: Drive Clean Emissions Inspection Report show failed reading for NO ppm:
Another headache.... ok my Saturn is 14 years old, so things are bound to fail on it.
I?ve included my last three Emissions Tests results below, (done every 2 years). In 2006 my NOx result was a close pass. In 2008 the result for NOx was a bad fail. However the HC and CO measurements have not been a problem.
The info included suggests for high NOx on driving test...
1.-inoperative EGR... my EGR valve is fine, not the original, I did replace it with a new one 4 years ago.2.-excessive lean air/fuel ratio... I did replace the air filter 2 months before the test. I have used fuel injector and fuel system cleaners over this year
3.-malfunctioning catalytic converter - 3-way catalyst only.... this is possible with the age of the car, but I would think that the HC and CO readings would be higher too? There is good exhaust out of my tailpipe, so the cat is not plugged. I did not measure the pipe pressure before and after the cat though.4.-excessive spark advance... I change the spark plugs myself, gap them properly at 0.040?, the current four are one year old, Champion brand RC12YC, traditional flat copper core. I do not use platinum or iridium plugs.
5.-faulty thermostatic air cleaner system.... air filter is new, I did clean the throttle body valve this summer.6.-engine deposits or mechanical defect..... my engine runs and idles well. I do oil changes every 5000 - 7000 Km, mostly highway driving. This past summer I did do a mild engine flush using 1 L of ATF transmission fluid before an oil change. Folks have recommended this over concentrated flush chemicals, never had problems.
7.-faulty cooling system... I did replace a failed water pump in September, coolant was flushed and replaced. I did replace my accessory belt. I also replaced a faulty temp sensor in July?08. The pigtail harness to this coolant temp sensor was corroded and caused running problems with my engine 2 weeks ago (stalling). I was stranded out of town when this happened and took the car to a shop where this pigtail harness was replaced. Engine was running fine thereafter and this 2008 Emissions Test was performed at the same shop immediately after the repair.Any suggestions? .... Much appreciated. Thanks, Roger
Three Emissions Tests results...
-------------------------------------------------------------------------------------------------------- Results: Nov 2008
HC ppm @ 40Km/h ASM 2525, 23, limit 75, pass; @ Idle, 53, limit 200, pass
CO % @ 40Km/h ASM 2525, 0.01, limit 0.42, pass; @ Idle, 0.00, limit 1, pass
NO ppm @ 40Km/h ASM 2525, 1149, limit 576, FAIL; @ Idle, -, limit -, - (not done)
@ 40Km/h RPM 1780, Dilution 14.41, valid @ Idle, RPM 745, Dilution 12.80, valid
Analyzer Software Version: 4.54
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-------------------------------------------------------------------------------------------------------- Results: 2006
HC ppm @ 40Km/h ASM 2525, 7, limit 75, pass; @ Idle, 20, limit 200, pass
CO % @ 40Km/h ASM 2525, 0.01, limit 0.42, pass; @ Idle, 0.16, limit 1, pass
NO ppm @ 40Km/h ASM 2525, 550, limit 576, pass; @ Idle, -, limit -, - (not done)
@ 40Km/h RPM 2858, Dilution 14.2, valid @ Idle, RPM 751, Dilution 12.6, valid
Analyzer Software Version: 3.53
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-------------------------------------------------------------------------------------------------------- Results: 2004
HC ppm @ 40Km/h ASM 2525, 33, limit 86, pass; @ Idle, 196, limit 200, pass
CO % @ 40Km/h ASM 2525, 0.02, limit 0.48, pass; @ Idle, 0.33, limit 1, pass
NO ppm @ 40Km/h ASM 2525, 301, limit 663, pass; @ Idle, -, limit -, - (not done)
@ 40Km/h RPM 1982, Dilution 14.9, valid @ Idle, RPM 760, Dilution 13.20, valid
Analyzer Software Version: 3.16
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