1987 Honda Prelude Failed Emissions

1987 HONDA PRELUDE
199,000 MILES • 4 CYL • 2WD • MANUAL
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SEPHRON1
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We took our car in to get emissions tested and it failed the CO emissions at 7% but was fine on the HC. so we had diagnostics run on it and they replaced the O2 sensor but it still failed the CO emissions with 6%. The catalytic converter is fine and we recently had the oil changed, but not the air filter. Will changing the air filter and putting engine cleaner and premium help it pass ? Is there anything else we can do its the only car we have?
Sep 16, 2009 at 4:12 PM
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KHLOW2008
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Hi sephron1,

If the air cleaner is badly clogged, replacing it would help.

Here are some comments that you can consider.

Clean the EGR system.

If the vehicle had been driven slow most of the time, perform some hard driving, ie race the engine with some hard acceleration. this would help clear out some carbons.

Check spark plugs for fouling and gapping.

Check valve clearances.

Check ignition timng.

Some fuel cleaner and premium should help.

If all else fails, the last resort would be to replace the catalytic converter. It is not performing as well as it should.
Sep 19, 2009 at 11:16 AM