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Smog Test - High HC at 15mph

2000 Lexus ES 300, 65K miles. 60K service completed less than a year ago: new O2 sensors, knock- sensors, filters, fluids, throttle-body cleaning, etc.

HC (PPM) @ 15mph (1578 RPM) MAX/AVERAGE/MEASURED

51/9/49

HC (PPM) @ 25mph (2109 RPM)

35/7/7

Other results were good (CO, NO, O2 (0.0), CO2 (14.8/14.9)). But it almost failed the 15mph HC test. Could this mean the engine wasn't warm enough during the 15mph tests? Or something more serious?

Reply to
taxenqs
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Try a bottle of Chevron Techron Fuel System Cleaner next time. Use NGK Iridium spark plugs. There isn't a lot of tune up you can do in modern engines.

Reply to
johngdole

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