1994 ISUZU TROOPER
200,000 MILES
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failed smog test ca no ppm high
Mar 21, 2013 at 8:08 PM
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WRENCHTECH
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If you mean "Nox", that is caused by high combustion temperatures. You need to look at things like engine temp, ignition timing and EGR operation.
Mar 21, 2013 at 8:13 PM