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1989 Toyota Camry 4cyl 282,500 miles failed HC test

My Toyota failed HC Hydrocarbons. I missed it by 19 points. Timing was at 7 BTDC I set it to 10 BTDC as it specifies for this vehicle. All else seems good with the engine. I changed plugs last fall and cap & rotor a few weeks prior to the initial test. Just changed oil too. I have since changed the top O2 sensor. Should this help on the retest? Otherwise I will be appling for the CAP program. 1 other question; should the transmission be in 4th gear (overdrive) when the test is done since it's tested at 15 MPH and 25 MPH and I usually lock it into 3rd below 40 mph?
Answer:

Last question first... The smog machine has a specific RPM requirement during both the 15mph and 25mph portion of the smog test; so the smog technician has to have your Toyota in which every gear suits the smog machine's required engine RPMs. Typically during the 15mph portion the transmission should be in 2nd gear, and during the 25mph portion the transmission should be in 3rd gear. As far as the high HC, changing the oxygen sensor may help lower it if the HC fault was due to an air/fuel mixture problem. The O2 sensor controls fuel delivery. If the CO amount your engine produced was not near the average result indicated on your smog check report, it may have caused the high HC fault. Since you mention having replaced the sparkplugs, distributor cap and rotor recently, the high HC problem may be due to either too high or too low CO... Though I can't confirm this without knowing the CO results. You may want to consider using our online VIR diagnosis system and have one of our smog technicians take a look at your Toyota's overall smog check results. www.smogtips.com/smog_evaluations.cfm The CAP program is always an excellent state assistance service to use. I'd recommend getting a new smog test with the replaced O2 sensor and corrected timing, and if your Toyota still fails the smog check, go ahead and apply for CAP. posted by SmogTips Support

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