Failing Emissions Test
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Failing Emissions Test
My '88 F-150 with a 4.9 and Borg-Warner T-18 four speed just failed an emissions test. Carbon monoxide and hydrocarbons, the only two gasses measured, were both high. However the problem only occurred at the idle speed portion of the test. At 2500 RPM everything checks out. The check engine light illuminates at idle, but goes out above idle under power. The check engine light will remain illuminated above idle speed if the throttle is closed, such as when coasting down a hill. I have not yet read the trouble codes. Does anybody have any ideas about this?
